http://fswiki.us/api.php?action=feedcontributions&feedformat=atom&user=AGfswiki.us - User contributions [en]2026-07-26T16:40:02ZUser contributionsMediaWiki 1.34.1http://fswiki.us/index.php?title=Suspension_Geometry_and_Kinematics&diff=1914Suspension Geometry and Kinematics2020-08-18T15:16:04Z<p>AG: /* Kingpin */</p>
<hr />
<div>==Track width==<br />
This has 4 main considerations:<br />
* If the track is too narrow, the car may fail the 60deg tilt test<br />
* Narrower track increases load transfer, reducing lateral grip<br />
* Narrower track reduces rear wing, front wing, and undertray width, reducing aero potential<br />
* Narrower track tightens the racing line - can be very beneficial on a manuverability emphasized course, such as the autoX and endurance.<br />
These need to be analyzed for an adequate tradeoff.<br />
<br />
==Wheelbase==<br />
Considerations:<br />
* 1525mm minimum set by rules<br />
* Shorter generally makes a more compact car, that will at least in theory be lighter and have less yaw inertia<br />
* Shorter reduces steering angle requirement per a given corner radius, geometrically speaking<br />
* Shorter makes the car less stable at high speeds, but the minimum set is well above any sort of safety concern<br />
* Longer can allow more downforce, at least in theory, from undertray and side aero. But, is it worth the penalty?<br />
* Longer can allow more flexibilty with CG longtitudonal location<br />
An adequate compromise must be made.<br />
<br />
==Camber==<br />
Camber is the front view angle of the tire from the vertical axis. The top of the tire pointing inwards is referred to as "negative camber". Positive camber is never desirable (from a traction POV. Positive camber can improve driveability, as seen on 1950s F1 cars).<br />
<br />
<br />
Why? Evening out the contact patch pressure, under lateral load.[[File:Annotation 2020-05-25 001418.png|center|middle|thumb|Camber Justification ]]<br />
<br />
<br />
As the car rolls, the tire rolls that same amount - so, 2deg of body roll is 2deg of positive tire camber - bad! How to solve?<br />
<br />
<br />
Either static camber (fixed), or "dynamic" - "Camber gain", from the suspension linkage. By making the upper a-arm shorter than the lower, and the inboard points closer together than the outboard, the wheel will gain negative camber with wheel travel - that is, canceling out part of the camber lost in roll. An easy way to quantify the camber gain is the Front-view swing arm length (FVSAL) - the line from the wheel center to the Instant Center (IC) of the 2 arms, found at the intersection of the extension of the arms line of action. This can allow for a simple sin/cosine relation for camber gain, although it is idealized since the FVSAL doesnt stay constant through the travel. For reference, the 2018 Ryerson car had a 45inch FVSAL, allowing it to run relatively minimal static camber.<br />
<br />
<br />
Why would that be desirable? static camber could cause the inner part of the tire to overheat on the straights, and so even if the camber during a corner is ideal, the tire wear and tire temperature would say otherwise. So, general considerations in the solution:<br />
* Minimize roll, to reduce the need for static camber. However, a stiffer car will be more upset by bumps, which is difficult to quantify.<br />
* Use camber gain, but remember that in pitch camber gain will reduce the longitudonal grip (for longt, you want 0 camber)<br />
* Account for camber deflection sources, and build in adjustabity of at least static camber.<br />
The "ideal" compromise of these factors has requires detailed analysis.<br />
<br />
==Toe==<br />
A minor adjustment. A stability fine tuning tool, to make the car feel better for the driver. Not a major performance item. Generally, toe out (front of wheels pointing outwards) is for response, and toe in is for stability. You would almost never see toe out on the rear, while the front is likely to be toe out.<br />
<br />
<br />
However, that is within the usable range (-1:1deg?). Compliance that is often present, especially on the rear, can turn an otherwise decent car into an unpredictable deathtrap. Take into consideration:<br />
* Toe base (mechanical advantage of the toe arm)<br />
* Bolted joint tolerance<br />
* Anything that is not axially loaded or not a direct line of action<br />
<br />
As Claude Rouelle said:<br />
<br />
<br />
“Nothing is rigid; 0.2mm of deflection here and 0.3mm of deflection there, and suddenly your front camber or you rear toe is far, far away from what you thought it was. From the driver input (steering wheel, brake pedal, throttle) to the tyres’ contact patch, there are dozens of non-linear springs, dampers, and hysteresis that compromise the racecar’s response to that driver input. [[Compliance]] is the biggest enemy of your driver’s Control and Confidence.”<br />
==Kingpin==<br />
Not that important for vehicle handling - Its main effect is on reducing scrub radius - but, scrub radius as well is less important on a racetrack with no major curbs/bumps where the steering wheel can be jerked around.<br />
<br />
<br />
Kingpin adds a VERY minor self centering effect (can be usually neglected relative to caster, even at 10+ deg), and an also minor but not neglegible positive camber gain in steer. This is a symmetric effect left to right, but not once caster is taken into account.<br />
<br />
<br />
However, to give an example, on a car with 4deg of caster and 8deg of kingpin, the negative camber gain from caster would overpower the kingpin by at least ~2-3x. There are equations to calculate this, but you can also set up your solidworks sketches correctly, and observe the effect in the sketches (if they are made movable), or in the assembly.<br />
<br />
==Caster==<br />
[[File:Image161.png|right|middle|thumb|Caster Offset ]]Caster is the side-view angle of the steering axis to the vertical. It affects:<br />
* Mechanical trail<br />
** Steering effort<br />
** "sense of direction the wheels want to go to" - i.e, where would the wheels steer if you let go of the steering wheel<br />
** High speed stability<br /><br />
* Jacking<br />
** Low speed oversteer inducing, as a tuning mechanism<br />
** Another variable in steering effort<br />
** Consider it as adding roll also!<br />
* Steer camber<br />
** Negative camber on outside wheel, positive on inner - both good! <br />
*** But, do you want more camber for a tight hairpin than for a wide sweeper? I dont think so! in practice, this can be neglegible if caster is low enough, but it is a factor.<br />
<br />
Remember, you can have "Caster offset", to independently affect mechanical trail (the most important one) from the other 2.<br />
<br />
<br />
<br />
<br />
Also, you dont want to drown out the pneumatic trail with too much mechanical trail. Youll just end up with super heavy steering all the time, instead of giving the driver a signal of understeer like the pneumatic trail should.<br />
<br />
<br />
<br />
<br />
==Roll Center==<br />
==Bump Center==<br />
==CAD Tips==<br />
Its helpful to set the CAD up for easy adjustment.<br />
<br />
<br />
That can be done by:<br />
* Integrating the suspension geometry sketches into the frame file<br />
* Having a few levels of sketches, set up for ease of parameter adjustment:<br />
** A 2D "geometry sketch", that isnt movable, and has all the critical angles and dimensions set, as well as static roll center visible with driven dimensions<br />
** A 3D "geometry sketch", adding in caster<br />
** A 3D "linkage sketch" - movable, with equal length relations to the "geometry sketch" - so that it can be cycled through travel, while getting geometry updates from the geometry sketch.<br />
It can look like this:<br />
<br />
[[File:Image162.png|center|middle|thumb|Movable Sketch ]]<br />
<br />
<br />
These sketches would then have in-context relations to the bellcrank, a-arms, uprights etc to have their geometry update accordingly to geometry sketch changes.<br />
<br />
<br />
<br />
<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]</div>AGhttp://fswiki.us/index.php?title=Underbody&diff=1913Underbody2020-08-18T15:10:44Z<p>AG: </p>
<hr />
<div>Placeholder page for underbody aerodynamics<br />
<br />
Things that are worth writing about here are probably:<br />
<br />
simple expansion based diffusers<br />
complex three dimensional diffuser flow<br />
vortex flat plate interactions<br />
<br />
<br />
<br />
<br />
Willem Toet's [https://www.racetechmag.com/2017/08/willem-toet-explains-motorsport-diffusers/ article on diffusers] is probably the best place to start learning about diffuser design.<br />
<br />
<br />
<br />
<br />
Keep in mind, while many teams know how to design a "good" undertray, many are plauged by insufficient stiffness (both mounting and tray itself) and too low ride height to work effectively. A bumpy track can also play a significant role - consider, if your undertray is 0.5in above the ground, if the asphalt variations are not a significant % variation.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
[[Category:Body and Aero]]</div>AGhttp://fswiki.us/index.php?title=User:AG&diff=1640User:AG2020-05-24T23:17:16Z<p>AG: </p>
<hr />
<div>Ryerson Formula Racing (FSAE)<br />
<br />
<br />
Susp Lead 2016-2018<br />
<br />
<br />
Engineering, Frame, VD lead 2019<br />
<br />
<br />
Team Captain and Frame lead 2020<br />
<br />
<br />
<br />
<br />
Ryerson Baja<br />
<br />
<br />
Susp Lead 2017<br />
<br />
<br />
Engineering Lead 2018</div>AGhttp://fswiki.us/index.php?title=User:AG&diff=1637User:AG2020-05-24T21:39:09Z<p>AG: Created page with "Ryerson Formula Racing (FSAE) Susp Lead 2016-2018 Engineering, Frame, VD lead 2019 Team Captain and Frame lead 2020"</p>
<hr />
<div>Ryerson Formula Racing (FSAE)<br />
<br />
<br />
Susp Lead 2016-2018<br />
<br />
<br />
Engineering, Frame, VD lead 2019<br />
<br />
<br />
Team Captain and Frame lead 2020</div>AGhttp://fswiki.us/index.php?title=Suspension_Geometry_and_Kinematics&diff=1636Suspension Geometry and Kinematics2020-05-24T21:30:44Z<p>AG: </p>
<hr />
<div>==Track width==<br />
This has 4 main considerations:<br />
* If the track is too narrow, the car may fail the 60deg tilt test<br />
* Narrower track increases load transfer, reducing lateral grip<br />
* Narrower track reduces rear wing, front wing, and undertray width, reducing aero potential<br />
* Narrower track tightens the racing line - can be very beneficial on a manuverability emphasized course, such as the autoX and endurance.<br />
These need to be analyzed for an adequate tradeoff.<br />
<br />
==Wheelbase==<br />
Considerations:<br />
* 1525mm minimum set by rules<br />
* Shorter generally makes a more compact car, that will at least in theory be lighter and have less yaw inertia<br />
* Shorter reduces steering angle requirement per a given corner radius, geometrically speaking<br />
* Shorter makes the car less stable at high speeds, but the minimum set is well above any sort of safety concern<br />
* Longer can allow more downforce, at least in theory, from undertray and side aero. But, is it worth the penalty?<br />
* Longer can allow more flexibilty with CG longtitudonal location<br />
An adequate compromise must be made.<br />
<br />
==Camber==<br />
Camber is the front view angle of the tire from the vertical axis. The top of the tire pointing inwards is referred to as "negative camber". Positive camber is never desirable.<br />
<br />
<br />
Why? Evening out the contact patch pressure, under lateral load.[[File:Annotation 2020-05-25 001418.png|center|middle|thumb|Camber Justification ]]<br />
<br />
<br />
As the car rolls, the tire rolls that same amount - so, 2deg of body roll is 2deg of positive tire camber - bad! How to solve?<br />
<br />
<br />
Either static camber (fixed), or "dynamic" - "Camber gain", from the suspension linkage. By making the upper a-arm shorter than the lower, and the inboard points closer together than the outboard, the wheel will gain negative camber with wheel travel - that is, canceling out part of the camber lost in roll. An easy way to quantify the camber gain is the Front-view swing arm length (FVSAL) - the line from the wheel center to the Instant Center (IC) of the 2 arms, found at the intersection of the extension of the arms line of action. This can allow for a simple sin/cosine relation for camber gain, although it is idealized since the FVSAL doesnt stay constant through the travel. For reference, the 2018 Ryerson car had a 45inch FVSAL, allowing it to run relatively minimal static camber.<br />
<br />
<br />
Why would that be desirable? static camber could cause the inner part of the tire to overheat on the straights, and so even if the camber during a corner is ideal, the tire wear and tire temperature would say otherwise. So, general considerations in the solution:<br />
* Minimize roll, to reduce the need for static camber. However, a stiffer car will be more upset by bumps, which is difficult to quantify.<br />
* Use camber gain, but remember that in pitch camber gain will reduce the longitudonal grip (for longt, you want 0 camber)<br />
* Account for camber deflection sources, and build in adjustabity of at least static camber.<br />
The "ideal" compromise of these factors has requires detailed analysis.<br />
==Toe==<br />
A minor adjustment. A stability fine tuning tool, to make the car feel better for the driver. Not a major performance item. Generally, toe out (front of wheels pointing outwards) is for response, and toe in is for stability. You would almost never see toe out on the rear, while the front is likely to be toe out.<br />
<br />
<br />
However, that is within the usable range (-1:1deg?). Compliance that is often present, especially on the rear, can turn an otherwise decent car into an unpredictable deathtrap. Take into consideration:<br />
* Toe base (mechanical advantage of the toe arm)<br />
* Bolted joint tolerance<br />
* Anything that is not axially loaded or not a direct line of action<br />
<br />
As Claude Rouelle said:<br />
<br />
<br />
“Nothing is rigid; 0.2mm of deflection here and 0.3mm of deflection there, and suddenly your front camber or you rear toe is far, far away from what you thought it was. From the driver input (steering wheel, brake pedal, throttle) to the tyres’ contact patch, there are dozens of non-linear springs, dampers, and hysteresis that compromise the racecar’s response to that driver input. Compliance is the biggest enemy of your driver’s Control and Confidence.”<br />
==Kingpin==<br />
==Caster==<br />
[[File:Image161.png|right|middle|thumb|Caster Offset ]]Caster is the side-view angle of the steering axis to the vertical. It affects:<br />
* Mechanical trail<br />
** Steering effort<br />
** "sense of direction the wheels want to go to" - i.e, where would the wheels steer if you let go of the steering wheel<br />
** High speed stability<br /><br />
* Jacking<br />
** Low speed oversteer inducing, as a tuning mechanism<br />
** Another variable in steering effort<br />
** Consider it as adding roll also!<br />
* Steer camber<br />
** Negative camber on outside wheel, positive on inner - both good! <br />
*** But, do you want more camber for a tight hairpin than for a wide sweeper? I dont think so! in practice, this can be neglegible if caster is low enough, but it is a factor.<br />
<br />
Remember, you can have "Caster offset", to independently affect mechanical trail (the most important one) from the other 2.<br />
<br />
<br />
<br />
<br />
Also, you dont want to drown out the pneumatic trail with too much mechanical trail. Youll just end up with super heavy steering all the time, instead of giving the driver a signal of understeer like the pneumatic trail should.<br />
<br />
<br />
<br />
<br />
==Roll Center==<br />
==Bump Center==<br />
==CAD Tips==<br />
Its helpful to set the CAD up for easy adjustment.<br />
<br />
<br />
That can be done by:<br />
* Integrating the suspension geometry sketches into the frame file<br />
* Having a few levels of sketches, set up for ease of parameter adjustment:<br />
** A 2D "geometry sketch", that isnt movable, and has all the critical angles and dimensions set, as well as static roll center visible with driven dimensions<br />
** A 3D "geometry sketch", adding in caster<br />
** A 3D "linkage sketch" - movable, with equal length relations to the "geometry sketch" - so that it can be cycled through travel, while getting geometry updates from the geometry sketch.<br />
It can look like this:<br />
<br />
[[File:Image162.png|center|middle|thumb|Movable Sketch ]]<br />
<br />
<br />
These sketches would then have in-context relations to the bellcrank, a-arms, uprights etc to have their geometry update accordingly to geometry sketch changes.<br />
<br />
<br />
<br />
<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]</div>AGhttp://fswiki.us/index.php?title=File:Annotation_2020-05-25_001418.png&diff=1635File:Annotation 2020-05-25 001418.png2020-05-24T21:14:24Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image2.png&diff=1634File:Image2.png2020-05-24T21:09:56Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=Suspension_Geometry_and_Kinematics&diff=1633Suspension Geometry and Kinematics2020-05-24T21:08:56Z<p>AG: </p>
<hr />
<div>==Track width==<br />
This has 4 main considerations:<br />
* If the track is too narrow, the car may fail the 60deg tilt test<br />
* Narrower track increases load transfer, reducing lateral grip<br />
* Narrower track reduces rear wing, front wing, and undertray width, reducing aero potential<br />
* Narrower track tightens the racing line - can be very beneficial on a manuverability emphasized course, such as the autoX and endurance.<br />
These need to be analyzed for an adequate tradeoff.<br />
<br />
==Wheelbase==<br />
Considerations:<br />
* 1525mm minimum set by rules<br />
* Shorter generally makes a more compact car, that will at least in theory be lighter and have less yaw inertia<br />
* Shorter reduces steering angle requirement per a given corner radius, geometrically speaking<br />
* Shorter makes the car less stable at high speeds, but the minimum set is well above any sort of safety concern<br />
* Longer can allow more downforce, at least in theory, from undertray and side aero. But, is it worth the penalty?<br />
* Longer can allow more flexibilty with CG longtitudonal location<br />
An adequate compromise must be made.<br />
<br />
==Camber==<br />
==Toe==<br />
==Kingpin==<br />
==Caster==<br />
[[File:Image161.png|right|middle|thumb|Caster Offset ]]Caster is the side-view angle of the steering axis to the vertical. It affects:<br />
* Mechanical trail<br />
** Steering effort<br />
** "sense of direction the wheels want to go to" - i.e, where would the wheels steer if you let go of the steering wheel<br />
** High speed stability<br /><br />
* Jacking<br />
** Low speed oversteer inducing, as a tuning mechanism<br />
** Another variable in steering effort<br />
** Consider it as adding roll also!<br />
* Steer camber<br />
** Negative camber on outside wheel, positive on inner - both good! <br />
*** But, do you want more camber for a tight hairpin than for a wide sweeper? I dont think so! in practice, this can be neglegible if caster is low enough, but it is a factor.<br />
<br />
Remember, you can have "Caster offset", to independently affect mechanical trail (the most important one) from the other 2.<br />
<br />
<br />
<br />
<br />
Also, you dont want to drown out the pneumatic trail with too much mechanical trail. Youll just end up with super heavy steering all the time, instead of giving the driver a signal of understeer like the pneumatic trail should.<br />
<br />
<br />
<br />
<br />
==Roll Center==<br />
==Bump Center==<br />
==CAD Tips==<br />
Its helpful to set the CAD up for easy adjustment.<br />
<br />
<br />
That can be done by:<br />
* Integrating the suspension geometry sketches into the frame file<br />
* Having a few levels of sketches, set up for ease of parameter adjustment:<br />
** A 2D "geometry sketch", that isnt movable, and has all the critical angles and dimensions set, as well as static roll center visible with driven dimensions<br />
** A 3D "geometry sketch", adding in caster<br />
** A 3D "linkage sketch" - movable, with equal length relations to the "geometry sketch" - so that it can be cycled through travel, while getting geometry updates from the geometry sketch.<br />
It can look like this:<br />
<br />
[[File:Image162.png|center|middle|thumb|Movable Sketch ]]<br />
<br />
<br />
These sketches would then have in-context relations to the bellcrank, a-arms, uprights etc to have their geometry update accordingly to geometry sketch changes.<br />
<br />
<br />
<br />
<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]</div>AGhttp://fswiki.us/index.php?title=File:Image161.png&diff=1632File:Image161.png2020-05-24T21:02:59Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=Suspension_Geometry_and_Kinematics&diff=1631Suspension Geometry and Kinematics2020-05-24T21:02:05Z<p>AG: </p>
<hr />
<div>==Track width==<br />
This has 4 main considerations:<br />
* If the track is too narrow, the car may fail the 60deg tilt test<br />
* Narrower track increases load transfer, reducing lateral grip<br />
* Narrower track reduces rear wing, front wing, and undertray width, reducing aero potential<br />
* Narrower track tightens the racing line - can be very beneficial on a manuverability emphasized course, such as the autoX and endurance.<br />
These need to be analyzed for an adequate tradeoff.<br />
==Wheelbase==<br />
Considerations:<br />
* 1525mm minimum set by rules<br />
* Shorter generally makes a more compact car, that will at least in theory be lighter and have less yaw inertia<br />
* Shorter reduces steering angle requirement per a given corner radius, geometrically speaking<br />
* Shorter makes the car less stable at high speeds, but the minimum set is well above any sort of safety concern<br />
* Longer can allow more downforce, at least in theory, from undertray and side aero. But, is it worth the penalty?<br />
* Longer can allow more flexibilty with CG longtitudonal location<br />
An adequate compromise must be made.<br />
==Camber==<br />
==Toe==<br />
==Kingpin==<br />
==Caster==<br />
==Roll Center==<br />
==Bump Center==<br />
==CAD Tips==<br />
Its helpful to set the CAD up for easy adjustment.<br />
<br />
<br />
That can be done by:<br />
* Integrating the suspension geometry sketches into the frame file<br />
* Having a few levels of sketches, set up for ease of parameter adjustment:<br />
** A 2D "geometry sketch", that isnt movable, and has all the critical angles and dimensions set, as well as static roll center visible with driven dimensions<br />
** A 3D "geometry sketch", adding in caster<br />
** A 3D "linkage sketch" - movable, with equal length relations to the "geometry sketch" - so that it can be cycled through travel, while getting geometry updates from the geometry sketch.<br />
It can look like this:<br />
<br />
<br />
[[File:Image162.png|center|middle|thumb|Movable Sketch ]]<br />
<br />
<br />
These sketches would then have in-context relations to the bellcrank, a-arms, uprights etc to have their geometry update accordingly to geometry sketch changes.<br />
<br />
<br />
<br />
<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]</div>AGhttp://fswiki.us/index.php?title=File:Image162.png&diff=1630File:Image162.png2020-05-24T21:01:02Z<p>AG: </p>
<hr />
<div>The grayed out damper dimension is a driven dimension. For practical use, you would add a dimension to the wheel travel, to fully define the sketch. At that point, you could monitor MR.</div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1629Tube Frame2020-05-24T20:49:25Z<p>AG: /* Design */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight, and manufacturing complexity while complying to the rules. One thing to remember is that the frame is basically a glorified bracket. As such, the frame designer is primarely concerned with accomedating other systems - in approximate order of importance:<br />
* Ergonomics: the driver<br />
* Suspension: A-arm pickup points, and less importantly the damper linkage (it can meet the design requirements in a few arrangements usually)<br />
* Powertrain/drivetrain: differential mounting is usually heavily reliant on frame. Engine removability!<br />
* Aero: things like ground clearence and framerail width for undertray.<br />
* Electrical: can usually work around everyone, right?<br />
<br />
===Driver Accomedation and CAD basics===<br />
It is helpful to start the frame CAD with a "driver sketch", so that the driver dimensions and margins of safety past the rules will set the dimensions of the entire frame. A driver sketch can look like this:<br />
<br />
<br />
[[File:Image159.png|center|middle|thumb|Driver Sketch ]]<br />
<br />
<br />
with a seprate sketch building up the Side view frame around it:<br />
<br />
<br />
[[File:Image80.png|center|middle|thumb|Driver Sketch and Side View Frame ]]The frame CAD is best set up with the help of both 2D and 3D sketches, and then with the use of "Weldments" - basically pre-configured sweep features, that get generated ontop of the sketches (the sketch being the neutral axis of the tube). It makes things quite easy to make, and to export later - Solidworks generates a "cut list", that is like a BOM but for tubes.<br />
<br />
<br />
As part of smart CAD practice, it is best to have a "master sketch" (or a few in this case due to the complexity) - so that the entire frame design is controlled at the top of the part tree, and so that you dont have to go to 10 different features just to make one change. Learn to work with driven dimensions, and construction geometry. 3D sketches are computationally difficult, so you may occasionally see weird bugs with things going over defined even though they shouldnt. To mitigate this, keep complexity to a minimum, by reducing the number of dimensions and sketch lines per 3D sketch. One example layout would be this:<br />
* Driver Sketch (2D)<br /><br />
* Side View frame (2D)<br />
* Bulkhead (2D, usually)<br />
* Front Hoop (2D or 3D sketch on a plane)<br />
* Main Hoop (3D sketch on a plane)<br />
* Front tubes (3D)<br />
* Middle tubes (3D)<br />
* Rear tubes (3D)<br />
* Suspension 2d, then 3d.<br />
<br />
You get the idea.<br />
<br />
<br />
[[File:Image167.png|center|middle|thumb|Front Tubes, with bulkhead and FRH visible]]<br />
It is helpful to use in-context relations to deliver the suspension geometry to the a-arms, bellcranks, uprights, etc. That way, all adjustments to the geometry can be done in the frame file, and the changes would be up dated on assembly rebuild.[[File:Image107.png|center|middle|thumb|Suspension Integration into Frame file]]<br />
<br />
======<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
<br />
<br />
Note that because some tubes will inevitably take bending (primarely the side impact structure, due to impossible triangulation from the big empty space the driver occupies), there should be emphasis on reducing tube aspect ratio (by either upping diameter or reducing length), and adding gussets.<br />
===Tube Choice===<br />
====Alloys====<br />
[[Steel#1000 Series|10XX steel]] is cheap, easy to weld, readily available, and easy to machine.<br />
<br />
<br />
[[Steel#4000 Series|41XX steel]] is more expensive but stronger, more difficult to weld and machine (prone to cracking, heat treat required).<br />
<br />
<br />
Aluminum?<br />
<br />
====Method====<br />
ERW, DOM<br />
<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Cutting tubes to intersect each other is called coping or notching. Tubes can be notched by hand typically using a hole saw notcher, bench grinder, or die grinder. This process is very time consuming and meticulous. Tubes can also be profiled using a water jet or laser cutter.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|center|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit.You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
[[File:Image99.png|center|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixtures (also known as jigs) indicate the location of tubes within the frame. Fixtures can be made of many materials. Fixtures should start measurement from a [https://en.wikipedia.org/wiki/Datum_reference datum] (for example the front bulkhead). From the datum, important tubes should next be fixtured (suspension points, roll hoops, etc...).<br />
<br />
<br />
(Fixture gallery?)<br />
<br />
===Welding===<br />
{{Main|Welding}}<br />
Tubes should be cleaned before welding. Joints should have minimal gaps, otherwise welding will be difficult. Tubes must be welded around the entire circumference (rules link).<br />
<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
[[File:image41.png|right|middle|thumb|Configuring Hinge Joints]]<br />
<br />
===Solid-Body Frame FEA (Soldworks)===<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=File:Image107.png&diff=1628File:Image107.png2020-05-24T20:49:05Z<p>AG: </p>
<hr />
<div>Note - Purely a sample frame, not necesarely structurally sound nor rules legal.</div>AGhttp://fswiki.us/index.php?title=File:Image167.png&diff=1627File:Image167.png2020-05-24T20:46:54Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1626Tube Frame2020-05-24T20:45:06Z<p>AG: /* Design */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight, and manufacturing complexity while complying to the rules. One thing to remember is that the frame is basically a glorified bracket. As such, the frame designer is primarely concerned with accomedating other systems - in approximate order of importance:<br />
* Ergonomics: the driver<br />
* Suspension: A-arm pickup points, and less importantly the damper linkage (it can meet the design requirements in a few arrangements usually)<br />
* Powertrain/drivetrain: differential mounting is usually heavily reliant on frame. Engine removability!<br />
* Aero: things like ground clearence and framerail width for undertray.<br />
* Electrical: can usually work around everyone, right?<br />
<br />
===Driver Accomedation and CAD basics===<br />
It is helpful to start the frame CAD with a "driver sketch", so that the driver dimensions and margins of safety past the rules will set the dimensions of the entire frame. A driver sketch can look like this:<br />
<br />
<br />
[[File:Image159.png|center|middle|thumb|Driver Sketch ]]<br />
<br />
<br />
with a seprate sketch building up the Side view frame around it:<br />
<br />
<br />
[[File:Image80.png|center|middle|thumb|Driver Sketch and Side View Frame ]]The frame CAD is best set up with the help of both 2D and 3D sketches, and then with the use of "Weldments" - basically pre-configured sweep features, that get generated ontop of the sketches (the sketch being the neutral axis of the tube). It makes things quite easy to make, and to export later - Solidworks generates a "cut list", that is like a BOM but for tubes.<br />
<br />
<br />
As part of smart CAD practice, it is best to have a "master sketch" (or a few in this case due to the complexity) - so that the entire frame design is controlled at the top of the part tree, and so that you dont have to go to 10 different features just to make one change. Learn to work with driven dimensions, and construction geometry. 3D sketches are computationally difficult, so you may occasionally see weird bugs with things going over defined even though they shouldnt. To mitigate this, keep complexity to a minimum, by reducing the number of dimensions and sketch lines per 3D sketch. One example layout would be this:<br />
* Driver Sketch (2D)<br /><br />
* Side View frame (2D)<br />
* Bulkhead (2D, usually)<br />
* Front Hoop (2D or 3D sketch on a plane)<br />
* Main Hoop (3D sketch on a plane)<br />
* Front tubes (3D)<br />
* Middle tubes (3D)<br />
* Rear tubes (3D)<br />
* Suspension 2d, then 3d.<br />
<br />
You get the idea.<br />
<br />
<br />
<br />
<br />
<br />
It is helpful to use in-context relations to deliver the suspension geometry to the a-arms, bellcranks, uprights, etc. That way, all adjustments to the geometry can be done in the frame file, and the changes would be up dated on assembly rebuild.<br />
<br />
<br />
<br />
<br />
======<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
<br />
<br />
Note that because some tubes will inevitably take bending (primarely the side impact structure, due to impossible triangulation from the big empty space the driver occupies), there should be emphasis on reducing tube aspect ratio (by either upping diameter or reducing length), and adding gussets.<br />
===Tube Choice===<br />
====Alloys====<br />
[[Steel#1000 Series|10XX steel]] is cheap, easy to weld, readily available, and easy to machine.<br />
<br />
<br />
[[Steel#4000 Series|41XX steel]] is more expensive but stronger, more difficult to weld and machine (prone to cracking, heat treat required).<br />
<br />
<br />
Aluminum?<br />
<br />
====Method====<br />
ERW, DOM<br />
<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Cutting tubes to intersect each other is called coping or notching. Tubes can be notched by hand typically using a hole saw notcher, bench grinder, or die grinder. This process is very time consuming and meticulous. Tubes can also be profiled using a water jet or laser cutter.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|center|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit.You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
[[File:Image99.png|center|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixtures (also known as jigs) indicate the location of tubes within the frame. Fixtures can be made of many materials. Fixtures should start measurement from a [https://en.wikipedia.org/wiki/Datum_reference datum] (for example the front bulkhead). From the datum, important tubes should next be fixtured (suspension points, roll hoops, etc...).<br />
<br />
<br />
(Fixture gallery?)<br />
<br />
===Welding===<br />
{{Main|Welding}}<br />
Tubes should be cleaned before welding. Joints should have minimal gaps, otherwise welding will be difficult. Tubes must be welded around the entire circumference (rules link).<br />
<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
[[File:image41.png|right|middle|thumb|Configuring Hinge Joints]]<br />
<br />
===Solid-Body Frame FEA (Soldworks)===<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=File:Image159.png&diff=1625File:Image159.png2020-05-24T20:39:43Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image80.png&diff=1623File:Image80.png2020-05-24T20:35:31Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1619Tube Frame2020-05-24T20:32:38Z<p>AG: /* Design */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight, and manufacturing complexity while complying to the rules. One thing to remember is that the frame is basically a glorified bracket. As such, the frame designer is primarely concerned with accomedating other systems - in approximate order of importance:<br />
* Ergonomics: the driver<br />
* Suspension: A-arm pickup points, and less importantly the damper linkage (it can meet the design requirements in a few arrangements usually)<br />
* Powertrain/drivetrain: differential mounting is usually heavily reliant on frame. Engine removability!<br />
* Aero: things like ground clearence and framerail width for undertray.<br />
* Electrical: can usually work around everyone, right?<br />
<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
<br />
<br />
Note that because some tubes will inevitably take bending (primarely the side impact structure, due to impossible triangulation from the big empty space the driver occupies), there should be emphasis on reducing tube aspect ratio (by either upping diameter or reducing length), and adding gussets.<br />
===Tube Choice===<br />
====Alloys====<br />
[[Steel#1000 Series|10XX steel]]<br />
<br />
<br />
is cheap, easy to weld, readily available, and easy to machine.<br />
<br />
<br />
[[Steel#4000 Series|41XX steel]] is more expensive but stronger, more difficult to weld and machine (prone to cracking, heat treat required).<br />
<br />
<br />
Aluminum?<br />
<br />
<br />
<br />
<br />
====Method====<br />
ERW, DOM<br />
<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Cutting tubes to intersect each other is called coping or notching. Tubes can be notched by hand typically using a hole saw notcher, bench grinder, or die grinder. This process is very time consuming and meticulous. Tubes can also be profiled using a water jet or laser cutter.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|center|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit.You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
[[File:Image99.png|center|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixtures (also known as jigs) indicate the location of tubes within the frame. Fixtures can be made of many materials. Fixtures should start measurement from a [https://en.wikipedia.org/wiki/Datum_reference datum]<br />
<br />
<br />
(for example the front bulkhead). From the datum, important tubes should next be fixtured (suspension points, roll hoops, etc...).<br />
<br />
<br />
(Fixture gallery?)<br />
<br />
<br />
<br />
<br />
===Welding===<br />
{{Main|Welding}}<br />
<br />
<br />
<br />
<br />
: ''Main page: <a title="Welding">Welding</a>''Tubes should be cleaned before welding. Joints should have minimal gaps, otherwise welding will be difficult. Tubes must be welded around the entire circumference (rules link).<br />
<br />
<br />
<br />
<br />
(notes on welding chromoly vs DOM. recommended filler/wire/electrodes) (NOTE - Added to the welding section)<br />
<br />
<br />
<br />
<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
[[File:image41.png|right|middle|thumb|Configuring Hinge Joints]]<br />
<br />
===Solid-Body Frame FEA (Soldworks)===<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1618Tube Frame2020-05-24T20:24:37Z<p>AG: </p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight, and manufacturing complexity while complying to the rules.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
===Tube Choice===<br />
====Alloys====<br />
[[Steel#1000 Series|10XX steel]]<br />
<br />
<br />
is cheap, easy to weld, readily available, and easy to machine.<br />
<br />
<br />
[[Steel#4000 Series|41XX steel]] is more expensive but stronger, more difficult to weld and machine (prone to cracking, heat treat required).<br />
<br />
<br />
Aluminum?<br />
<br />
<br />
<br />
<br />
====Method====<br />
ERW, DOM<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Cutting tubes to intersect each other is called coping or notching. Tubes can be notched by hand typically using a hole saw notcher, bench grinder, or die grinder. This process is very time consuming and meticulous. Tubes can also be profiled using a water jet or laser cutter.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|center|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit.You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
[[File:Image99.png|center|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixtures (also known as jigs) indicate the location of tubes within the frame. Fixtures can be made of many materials. Fixtures should start measurement from a [https://en.wikipedia.org/wiki/Datum_reference datum]<br />
<br />
<br />
(for example the front bulkhead). From the datum, important tubes should next be fixtured (suspension points, roll hoops, etc...).<br />
<br />
<br />
(Fixture gallery?)<br />
<br />
<br />
<br />
<br />
===Welding===<br />
{{Main|Welding}}<br />
<br />
<br />
<br />
<br />
: ''Main page: <a title="Welding">Welding</a>''Tubes should be cleaned before welding. Joints should have minimal gaps, otherwise welding will be difficult. Tubes must be welded around the entire circumference (rules link).<br />
<br />
<br />
<br />
<br />
(notes on welding chromoly vs DOM. recommended filler/wire/electrodes) (NOTE - Added to the welding section)<br />
<br />
<br />
<br />
<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
[[File:image41.png|right|middle|thumb|Configuring Hinge Joints]]<br />
<br />
===Solid-Body Frame FEA (Soldworks)===<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Welding&diff=1617Welding2020-05-24T20:19:55Z<p>AG: </p>
<hr />
<div>==General Tips==<br />
<br />
* If it’s not held, it will deform<br />
* If it is held, but has gaps, it will deform (i.e, a tube joint should be precise)<br />
* If welds are asymmetric, it will deform<br />
* Fillet welds deform more than flat welds<br />
* Your jig is the “upper limit” of accuracy<br />
* The ONLY way to ensure it does not deform, is to gusset. An aid is well-ordered tacking (4 points)<br />
<br /><br />
<br />
4130 steel gets brittle when welded. To fix, Heat treat (either with an oxy-acetelyne torch, or a proper oven treatment). A potential way to avoid this is to weld with ER70S6 filler<span>(weaker, but produces more mallable welds) ([https://www.lincolnelectric.com/en-ca/support/welding-how-to/Pages/chrome-moly-detail.aspx?utm referrer=https://www.google.com/ source]). Unless sufficiently proven, it would not be advised to design a frame with a <3 FOS, without heat treatment. The usage of a single cylinder also without soft mounting may be enough to crack a non heat treated (or even heat treated?) frame.</span><br />
<br />
<br />
<span>Aluminum is more difficult generally, since the oxidation layer has a higher melting point than the layers underneath. So, a tendency to blow holes is the result. Not all aluminum alloys are weldable, and the ones that are will be very brittle unless heat treated properly in an oven.</span><br />
<br />
<br />
<br /><br />
==TIG==<br />
NOOOOOOOO YOU CAN'T JUST USE ONE HAND TO WELD<br />
<br />
<br />
<br />
<br />
Highly versatile. Control of heat and feed independently (one in each hand) - allowing for fine tuning of the weld to the material at hand. Can work for aluminum and steel. A good welder will be able to weld ~.06in aluminum, and .028 steel.<br />
<br />
<br />
The drawback is that it requires more skill, and more active work - making the welding slower and higher effort. While a begginer can learn to tack within less than 1h, to become capable of performing hours of structural welds takes more effort.<br />
==MIG==<br />
haha, welding gun go brrrrrrr<br />
<br />
<br />
<br />
<br />
Same science principle of TIG, but now the heat and the feed are combined into one torch, with a wire spool instead of "filler rods" also serving as the electrode to close the circuit. Advantage? easy to learn, and if you weld alot of the same tube thicknesses, its "set and forget". Fast and easy, while also allowing one hand use which makes reaching into difficult spots in the frame much easier. Disadvantage? harder to do thin and small stuff - .035in steel is roughly the limit. Welds are less pretty and slightly heavier. How much heavier? I've weighed a baja frame tacked and fully welded, and on a 72lb frame, the welds were 2.5lb. I dont have any numbers for TIG, but i'd be surprised if the difference is more than 1lb. The time saved however is substantial - that frame took ~5h of shop time (not welding time) to finish weld - from tacked frame tubes+tabs, to ready to paint. The formula frames i've worked on took multiple full days, by multiple welders.<br />
<br />
<br />
<br />
<br />
==Stick==<br />
Does anyone in FSAE use this?<br />
<br />
<br />
[[Category:Manufacturing Techniques]]</div>AGhttp://fswiki.us/index.php?title=Welding&diff=1616Welding2020-05-24T20:17:55Z<p>AG: </p>
<hr />
<div>==General Tips==<br />
<br />
* If it’s not held, it will deform<br />
* If it is held, but has gaps, it will deform (i.e, a tube joint should be precise)<br />
* If welds are asymmetric, it will deform<br />
* Fillet welds deform more than flat welds<br />
* Your jig is the “upper limit” of accuracy<br />
* The ONLY way to ensure it does not deform, is to gusset. An aid is well-ordered tacking (4 points)<br />
<br /><br />
<br />
4130 steel gets brittle when welded. To fix, Heat treat (either with an oxy-acetelyne torch, or a proper oven treatment). A potential way to avoid this is to weld with [https://www.lincolnelectric.com/en-ca/support/welding-how-to/Pages/chrome-moly-detail.aspx?utm referrer=https://www.google.com/ ER70 S6] <span>(weaker, but produces more mallable welds). Unless sufficiently proven, it would not be advised to design a frame with a <3 FOS, without heat treatment. The usage of a single cylinder also without soft mounting may be enough to crack a non heat treated (or even heat treated?) frame.</span><br />
<br />
<br />
<span>Aluminum is more difficult generally, since the oxidation layer has a higher melting point than the layers underneath. So, a tendency to blow holes is the result. Not all aluminum alloys are weldable, and the ones that are will be very brittle unless heat treated properly in an oven.</span><br />
<br />
<br />
<br /><br />
==TIG==<br />
NOOOOOOOO YOU CAN'T JUST USE ONE HAND TO WELD<br />
<br />
<br />
<br />
<br />
Highly versatile. Control of heat and feed independently (one in each hand) - allowing for fine tuning of the weld to the material at hand. Can work for aluminum and steel. A good welder will be able to weld ~.06in aluminum, and .028 steel.<br />
<br />
<br />
The drawback is that it requires more skill, and more active work - making the welding slower and higher effort. While a begginer can learn to tack within less than 1h, to become capable of performing hours of structural welds takes more effort.<br />
==MIG==<br />
haha, welding gun go brrrrrrr<br />
<br />
<br />
<br />
<br />
Same science principle of TIG, but now the heat and the feed are combined into one torch, with a wire spool instead of "filler rods" also serving as the electrode to close the circuit. Advantage? easy to learn, and if you weld alot of the same tube thicknesses, its "set and forget". Fast and easy, while also allowing one hand use which makes reaching into difficult spots in the frame much easier. Disadvantage? harder to do thin and small stuff - .035in steel is roughly the limit. Welds are less pretty and slightly heavier. How much heavier? I've weighed a baja frame tacked and fully welded, and on a 72lb frame, the welds were 2.5lb. I dont have any numbers for TIG, but i'd be surprised if the difference is more than 1lb. The time saved however is substantial - that frame took ~5h of shop time (not welding time) to finish weld - from tacked frame tubes+tabs, to ready to paint. The formula frames i've worked on took multiple full days, by multiple welders.<br />
<br />
<br />
<br />
<br />
==Stick==<br />
Does anyone in FSAE use this?<br />
<br />
<br />
[[Category:Manufacturing Techniques]]</div>AGhttp://fswiki.us/index.php?title=Welding&diff=1615Welding2020-05-24T20:17:26Z<p>AG: </p>
<hr />
<div>==General Tips==<br />
* If it’s not held, it will deform<br />
* If it is held, but has gaps, it will deform (i.e, a tube joint should be precise)<br />
* If welds are asymmetric, it will deform<br />
* Fillet welds deform more than flat welds<br />
* Your jig is the “upper limit” of accuracy<br />
* The ONLY way to ensure it does not deform, is to gusset. An aid is well-ordered tacking (4 points)<br />
<br /><br />
<br />
4130 steel gets brittle when welded. To fix, Heat treat (either with an oxy-acetelyne torch, or a proper oven treatment). A potential way to avoid this is to weld with [https://www.lincolnelectric.com/en-ca/support/welding-how-to/Pages/chrome-moly-detail.aspx?utm referrer=https://www.google.com/ ER70 S6] <br />
<br />
<br />
<span>Aluminum is more difficult generally, since the oxidation layer has a higher melting point than the layers underneath. So, a tendency to blow holes is the result. Not all aluminum alloys are weldable, and the ones that are will be very brittle unless heat treated properly in an oven.</span><br />
<br />
<br />
<span></span><br />
<br />
<br />
(weaker, but produces more mallable welds). Unless sufficiently proven, it would not be advised to design a frame with a <3 FOS, without heat treatment. The usage of a single cylinder also without soft mounting may be enough to crack a non heat treated (or even heat treated?) frame.<br />
==TIG==<br />
NOOOOOOOO YOU CAN'T JUST USE ONE HAND TO WELD<br />
<br />
<br />
<br />
<br />
Highly versatile. Control of heat and feed independently (one in each hand) - allowing for fine tuning of the weld to the material at hand. Can work for aluminum and steel. A good welder will be able to weld ~.06in aluminum, and .028 steel.<br />
<br />
<br />
The drawback is that it requires more skill, and more active work - making the welding slower and higher effort. While a begginer can learn to tack within less than 1h, to become capable of performing hours of structural welds takes more effort.<br />
==MIG==<br />
haha, welding gun go brrrrrrr<br />
<br />
<br />
<br />
<br />
Same science principle of TIG, but now the heat and the feed are combined into one torch, with a wire spool instead of "filler rods" also serving as the electrode to close the circuit. Advantage? easy to learn, and if you weld alot of the same tube thicknesses, its "set and forget". Fast and easy, while also allowing one hand use which makes reaching into difficult spots in the frame much easier. Disadvantage? harder to do thin and small stuff - .035in steel is roughly the limit. Welds are less pretty and slightly heavier. How much heavier? I've weighed a baja frame tacked and fully welded, and on a 72lb frame, the welds were 2.5lb. I dont have any numbers for TIG, but i'd be surprised if the difference is more than 1lb. The time saved however is substantial - that frame took ~5h of shop time (not welding time) to finish weld - from tacked frame tubes+tabs, to ready to paint. The formula frames i've worked on took multiple full days, by multiple welders.<br />
<br />
<br />
<br />
<br />
==Stick==<br />
Does anyone in FSAE use this?<br />
<br />
<br />
[[Category:Manufacturing Techniques]]</div>AGhttp://fswiki.us/index.php?title=Tires&diff=1609Tires2020-05-24T19:50:26Z<p>AG: </p>
<hr />
<div>Good smelling round things<br />
=Theory Stuff=<br />
[[G-g Diagram|G-g Diagram]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
Tires are rubber based, with metal cords to re-enforce the structure both on the contact face, and on the vertical “side walls”. They are most commonly pneumatic (i.e inflated with air), and the result is a substantially stiff rolling structure, with the rubber generating adhesion as well as mechanical “interlocking” with the asphalt, with the result being friction.Why do tires matter? Put simply, they are the only link of the car with the ground. While almost all systems are critical for the car operation, the tires have a special role in the car’s performance - a race-car generates forces and accelerations, both through driver inputs and engine power. In this way, the tires are essentially a “gate-keeper”, where the limit of force (and as such acceleration) has an upper limit. So, more engine power, or more brake power, is only helpful if the tires can handle it. Why is more acceleration better? On a race-track, better acceleration/deceleration in a straight line means higher top speed and later braking before the corner. In a corner, better acceleration means higher corner speeds for a given radius (a=v^2/r).<br />It gets more complex. The tire is not fully rigid. If it was, it would not be able to “store” energy and generate cornering force. It is best to think of it like a spring, and cornering forces generate a torsion around the vertical axis going through the tire centerpoint. The twist angle generated is called “Slip angle”.<br />
<br />
[[File:image34.png|center|middle|thumb|Slip angle ]]<a class="image"><img class="thumbimage" src="/images/thumb/d/db/Image34.png/300px-Image34.png" srcset="/images/thumb/d/db/Image34.png/450px-Image34.png 1.5x, /images/thumb/d/db/Image34.png/600px-Image34.png 2x" alt="" width="300" height="420" /></a> Slip angle<br />
As the driver steers, the slip angle rises (and so does the cornering acceleration/force), but it does not do so linearly. This is a very important aspect of tire behavior.<br />
<br />
[[File:Image6.png|center|middle|thumb|Tire Comparison (fictional)]]<br />
<br />
<br />
<br />
Tire Comparison (fictional)Another related aspect is “alligning torque”, which is the moment the tire exerts around its centerline to return to neutral position (pre-deformation, i.e zero slip angle). How would it generate a moment? Only if the cornering force acts at a distance from the centerline of the tire.<br />
<br />
<br />
[[File:Image8.png|center|middle|thumb|Pneumatic trail ]]Now, why is this important? Because, we are not very sensetive to accelerations - i.e, the driver cant just feel in his body that the car is at peak acceleration very accurately. As such, the feedback of the tires through the steering wheel is very useful.<br />
<br />
<br />
[[File:Image151.png|link=https://www.semanticscholar.org/paper/Modeling-%2C-Analysis-and-Control-Methods-for-Vehicle-Takahashi/3f1dc5d4f82dce2e5a25cf20d470bbe68d4bb2b3|center|middle|thumb]]<br />
<br />
<br />
This is where it should be noted that this torque is also non linear, relative to slip angle and to cornering force! What the driver would feel is increasing steering force, then gradually decreasing, while the car is still increasing in cornering force. This is due to the slippage of the contact patch changing location.<br />
<br />
<br />
Another factor is the tire’s relationship to vertical load - i.e, why heavier cars dont corner as well as lighter cars. Tires operate with both “adhesion” and “Hysteresis” that can also be called as “mechanical interlocking” on a macro scale with the asphalt. A sidenote - The adhesion is vastly reduced in the rain, but the Hysteresis is not affected.<br />
<br />
<br />
[[File:Image14.png|link=https://www.fhwa.dot.gov/publications/research/safety/14065/002.cfm|center|middle|thumb|Mechanisms of grip ]]<br />
<br />
<br />
Now, the coefficient of friction of the tire is unitless, and it is the single most important measure of tire performance - or at least, the easiest one to see at a glance. We were taught in highschool physics that this friction coefficient is constant, and independent of surface area. That is not true! On some materials it may stay very near constant. But on a rubber tire, the coefficient is actually negatively correlated to vertical load - load goes up, coefficient goes down. This is substantial enough to be the single biggest justification for making a race-car lighter.<br />Below, a primary reason for this behavior is seen. This is the macro level “interlocking” of the rubber with the asphalt, a very conventional friction model. As the vertical (i.e normal) load increases, the rubber expands to fill the road ridges, but it begins to saturate (i.e it cannot go any further into the asphalt).<br />
<br />
<br />
[[File:Image29.png|link=http://insideracingtechnology.com/tirebkexerpt1.htm|center|middle|thumb|Load sensitivity ]]Consequentially, the coefficient = Fcornering/Fnormal decreases, as 1 unit of Fnormal increase results in a <1 unit of Fcornering increase - contributing to the value (being a ratio) to reduce.<br />
<br />
<br />
[[File:Image20.png|link=https://en.wikipedia.org/wiki/Tire_load_sensitivity|center|middle|thumb|Load Sensitivity ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
=List of Tires=<br />
[https://www.millikenresearch.com/fsaettc.html Formula SAE Tire Test Consortium]<br />
<br />
<br />
<br />
<br />
<br />
<br />
[https://www.hoosiertire.com/tires/circuit/spec/#panel-spec Hoosier Tires FSAE 2020]<br />
<br />
[http://www.avonmotorsport.com/resource-centre/tyre-applications/sae-formula-student Avon Tyres Formula Student]<br />
<br />
<br />
<br /><br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Dry==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
|Continental<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
|Goodyear<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| rowspan="9"|Hoosier <code><ref>https://www.hoosiertire.com/images/content/files/FormulaSAE19(1).pdf</ref></code><br /><br />
| <br />
|16.0 x 6.0-10<br /><br />
|~3.2kg<br /><br />
| <br />
| <br />
|-<br />
| <br />
|16.0 x 7.5-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|6.0/18.0-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 6.0-10<br />
|~4kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 7.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 6.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 7.5-10<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.5 x 7.0-13<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.0 x 7.5-13<br /><br />
|~5.4kg<br />
| <br />
| <br />
|-<br />
|Pirelli <br /><br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
==Wet==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
| rowspan="2"|Hoosier<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
=References=<br />
<code><references /></code></div>AGhttp://fswiki.us/index.php?title=Tires&diff=1607Tires2020-05-24T19:49:10Z<p>AG: </p>
<hr />
<div>Good smelling round things<br />
=Theory Stuff=<br />
[[G-g Diagram|G-g Diagram]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
Tires are rubber based, with metal cords to re-enforce the structure both on the contact face, and on the vertical “side walls”. They are most commonly pneumatic (i.e inflated with air), and the result is a substantially stiff rolling structure, with the rubber generating adhesion as well as mechanical “interlocking” with the asphalt, with the result being friction.Why do tires matter? Put simply, they are the only link of the car with the ground. While almost all systems are critical for the car operation, the tires have a special role in the car’s performance - a race-car generates forces and accelerations, both through driver inputs and engine power. In this way, the tires are essentially a “gate-keeper”, where the limit of force (and as such acceleration) has an upper limit. So, more engine power, or more brake power, is only helpful if the tires can handle it. Why is more acceleration better? On a race-track, better acceleration/deceleration in a straight line means higher top speed and later braking before the corner. In a corner, better acceleration means higher corner speeds for a given radius (a=v^2/r).<br />It gets more complex. The tire is not fully rigid. If it was, it would not be able to “store” energy and generate cornering force. It is best to think of it like a spring, and cornering forces generate a torsion around the vertical axis going through the tire centerpoint. The twist angle generated is called “Slip angle”.<br />
<br />
[[File:image34.png|center|middle|thumb|Slip angle ]]<a class="image"><img class="thumbimage" src="/images/thumb/d/db/Image34.png/300px-Image34.png" srcset="/images/thumb/d/db/Image34.png/450px-Image34.png 1.5x, /images/thumb/d/db/Image34.png/600px-Image34.png 2x" alt="" width="300" height="420" /></a> Slip angle<br />
<br />
<br />
<br />
<br />
As the driver steers, the slip angle rises (and so does the cornering acceleration/force), but it does not do so linearly. This is a very important aspect of tire behavior.<br />
<br />
[[File:Image6.png|center|middle|thumb|Tire Comparison (fictional)]]<br />
<br />
<br />
<a class="image"><img class="thumbimage" src="/images/thumb/1/15/Image6.png/300px-Image6.png" srcset="/images/thumb/1/15/Image6.png/450px-Image6.png 1.5x, /images/thumb/1/15/Image6.png/600px-Image6.png 2x" alt="" width="300" height="343" /></a> Tire Comparison (fictional)<br />
<br />
Tire Comparison (fictional)Another related aspect is “alligning torque”, which is the moment the tire exerts around its centerline to return to neutral position (pre-deformation, i.e zero slip angle). How would it generate a moment? Only if the cornering force acts at a distance from the centerline of the tire.<br />
<br />
<br />
[[File:Image8.png|center|middle|thumb|Pneumatic trail ]]<a class="image"><img class="thumbimage" src="/images/thumb/c/cc/Image8.png/300px-Image8.png" srcset="/images/thumb/c/cc/Image8.png/450px-Image8.png 1.5x, /images/c/cc/Image8.png 2x" alt="" width="300" height="173" /></a> Pneumatic trailNow, why is this important? Because, we are not very sensetive to accelerations - i.e, the driver cant just feel in his body that the car is at peak acceleration very accurately. As such, the feedback of the tires through the steering wheel is very useful.<br />
<br />
<br />
[[File:Image151.png|link=https://www.semanticscholar.org/paper/Modeling-%2C-Analysis-and-Control-Methods-for-Vehicle-Takahashi/3f1dc5d4f82dce2e5a25cf20d470bbe68d4bb2b3|center|middle|thumb]]<br />
<br />
<br />
This is where it should be noted that this torque is also non linear, relative to slip angle and to cornering force! What the driver would feel is increasing steering force, then gradually decreasing, while the car is still increasing in cornering force. This is due to the slippage of the contact patch changing location.<br />
<br />
<br />
Another factor is the tire’s relationship to vertical load - i.e, why heavier cars dont corner as well as lighter cars. Tires operate with both “adhesion” and “Hysteresis” that can also be called as “mechanical interlocking” on a macro scale with the asphalt. A sidenote - The adhesion is vastly reduced in the rain, but the Hysteresis is not affected.<br />
<br />
<br />
[[File:Image14.png|link=https://www.fhwa.dot.gov/publications/research/safety/14065/002.cfm|center|middle|thumb|Mechanisms of grip ]]<br />
<br />
<br />
Now, the coefficient of friction of the tire is unitless, and it is the single most important measure of tire performance - or at least, the easiest one to see at a glance. We were taught in highschool physics that this friction coefficient is constant, and independent of surface area. That is not true! On some materials it may stay very near constant. But on a rubber tire, the coefficient is actually negatively correlated to vertical load - load goes up, coefficient goes down. This is substantial enough to be the single biggest justification for making a race-car lighter.<br />Below, a primary reason for this behavior is seen. This is the macro level “interlocking” of the rubber with the asphalt, a very conventional friction model. As the vertical (i.e normal) load increases, the rubber expands to fill the road ridges, but it begins to saturate (i.e it cannot go any further into the asphalt).<br />
<br />
<br />
[[File:Image29.png|link=http://insideracingtechnology.com/tirebkexerpt1.htm|center|middle|thumb|Load sensitivity ]]Consequentially, the coefficient = Fcornering/Fnormal decreases, as 1 unit of Fnormal increase results in a <1 unit of Fcornering increase - contributing to the value (being a ratio) to reduce.<br />
<br />
<br />
[[File:Image20.png|link=https://en.wikipedia.org/wiki/Tire_load_sensitivity|center|middle|thumb|Load Sensitivity ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
=List of Tires=<br />
[https://www.millikenresearch.com/fsaettc.html Formula SAE Tire Test Consortium]<br />
<br />
<br />
<br />
<br />
[https://www.hoosiertire.com/tires/circuit/spec/#panel-spec Hoosier Tires FSAE 2020]<br />
<br />
[http://www.avonmotorsport.com/resource-centre/tyre-applications/sae-formula-student Avon Tyres Formula Student]<br />
<br />
<br />
<br /><br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Dry==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
|Continental<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
|Goodyear<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| rowspan="9"|Hoosier <code><ref>https://www.hoosiertire.com/images/content/files/FormulaSAE19(1).pdf</ref></code><br /><br />
| <br />
|16.0 x 6.0-10<br /><br />
|~3.2kg<br /><br />
| <br />
| <br />
|-<br />
| <br />
|16.0 x 7.5-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|6.0/18.0-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 6.0-10<br />
|~4kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 7.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 6.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 7.5-10<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.5 x 7.0-13<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.0 x 7.5-13<br /><br />
|~5.4kg<br />
| <br />
| <br />
|-<br />
|Pirelli <br /><br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
==Wet==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
| rowspan="2"|Hoosier<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
=References=<br />
<code><references /></code></div>AGhttp://fswiki.us/index.php?title=Tires&diff=1604Tires2020-05-24T19:39:58Z<p>AG: </p>
<hr />
<div>Good smelling round things<br />
=Theory Stuff=<br />
[[G-g Diagram|G-g Diagram]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
Tires are rubber based, with metal cords to re-enforce the structure both on the contact face, and on the vertical “side walls”. They are most commonly pneumatic (i.e inflated with air), and the result is a substantially stiff rolling structure, with the rubber generating adhesion as well as mechanical “interlocking” with the asphalt, with the result being friction.Why do tires matter? Put simply, they are the only link of the car with the ground. While almost all systems are critical for the car operation, the tires have a special role in the car’s performance - a race-car generates forces and accelerations, both through driver inputs and engine power. In this way, the tires are essentially a “gate-keeper”, where the limit of force (and as such acceleration) has an upper limit. So, more engine power, or more brake power, is only helpful if the tires can handle it. Why is more acceleration better? On a race-track, better acceleration/deceleration in a straight line means higher top speed and later braking before the corner. In a corner, better acceleration means higher corner speeds for a given radius (a=v^2/r).<br />It gets more complex. The tire is not fully rigid. If it was, it would not be able to “store” energy and generate cornering force. It is best to think of it like a spring, and cornering forces generate a torsion around the vertical axis going through the tire centerpoint. The twist angle generated is called “Slip angle”.<br />
<br />
<br />
<a class="image"><img class="thumbimage" src="/images/thumb/d/db/Image34.png/300px-Image34.png" srcset="/images/thumb/d/db/Image34.png/450px-Image34.png 1.5x, /images/thumb/d/db/Image34.png/600px-Image34.png 2x" alt="" width="300" height="420" /></a> Slip AngleAs the driver steers, the slip angle rises (and so does the cornering acceleration/force), but it does not do so linearly. This is a very important aspect of tire behavior.<br />
<br />
<br />
<br />
<br />
[[File:Image6.png|center|middle|thumb|Tire Comparison (fictional)]]<br />
<br />
<br />
<a class="image"><img class="thumbimage" src="/images/thumb/1/15/Image6.png/300px-Image6.png" srcset="/images/thumb/1/15/Image6.png/450px-Image6.png 1.5x, /images/thumb/1/15/Image6.png/600px-Image6.png 2x" alt="" width="300" height="343" /></a> Tire Comparison (fictional)Another related aspect is “alligning torque”, which is the moment the tire exerts around its centerline to return to neutral position (pre-deformation, i.e zero slip angle). How would it generate a moment? Only if the cornering force acts at a distance from the centerline of the tire.<br />
<br />
<br />
[[File:Image8.png|center|middle|thumb|Pneumatic trail ]]Now, why is this important? Because, we are not very sensetive to accelerations - i.e, the driver cant just feel in his body that the car is at peak acceleration very accurately. As such, the feedback of the tires through the steering wheel is very useful.<br />
<br />
<br />
[[File:Image151.png|link=https://www.semanticscholar.org/paper/Modeling-%2C-Analysis-and-Control-Methods-for-Vehicle-Takahashi/3f1dc5d4f82dce2e5a25cf20d470bbe68d4bb2b3|center|middle|thumb]]<br />
<br />
<br />
This is where it should be noted that this torque is also non linear, relative to slip angle and to cornering force! What the driver would feel is increasing steering force, then gradually decreasing, while the car is still increasing in cornering force. This is due to the slippage of the contact patch changing location.<br />
<br />
<br />
<br />
<br />
Another factor is the tire’s relationship to vertical load - i.e, why heavier cars dont corner as well as lighter cars. Tires operate with both “adhesion” and “Hysteresis” that can also be called as “mechanical interlocking” on a macro scale with the asphalt. A sidenote - The adhesion is vastly reduced in the rain, but the Hysteresis is not affected.<br />
<br />
<br />
<br />
<br />
[[File:Image14.png|link=https://www.fhwa.dot.gov/publications/research/safety/14065/002.cfm|center|middle|thumb|Mechanisms of grip ]]<br />
<br />
<br />
Now, the coefficient of friction of the tire is unitless, and it is the single most important measure of tire performance - or at least, the easiest one to see at a glance. We were taught in highschool physics that this friction coefficient is constant, and independent of surface area. That is not true! On some materials it may stay very near constant. But on a rubber tire, the coefficient is actually negatively correlated to vertical load - load goes up, coefficient goes down. This is substantial enough to be the single biggest justification for making a race-car lighter.<br />Below, a primary reason for this behavior is seen. This is the macro level “interlocking” of the rubber with the asphalt, a very conventional friction model. As the vertical (i.e normal) load increases, the rubber expands to fill the road ridges, but it begins to saturate (i.e it cannot go any further into the asphalt).<br />
<br />
<br />
[[File:Image29.png|link=http://insideracingtechnology.com/tirebkexerpt1.htm|center|middle|thumb|Load sensitivity ]]Consequentially, the coefficient = Fcornering/Fnormal decreases, as 1 unit of Fnormal increase results in a <1 unit of Fcornering increase - contributing to the value (being a ratio) to reduce.<br />
<br />
<br />
<br />
<br />
[[File:Image20.png|link=https://en.wikipedia.org/wiki/Tire_load_sensitivity|center|middle|thumb|Load Sensitivity ]]<br />
<br />
<br />
<br />
<br />
=List of Tires=<br />
[https://www.millikenresearch.com/fsaettc.html Formula SAE Tire Test Consortium]<br />
<br />
<br />
[https://www.hoosiertire.com/tires/circuit/spec/#panel-spec Hoosier Tires FSAE 2020]<br />
<br />
<br />
[http://www.avonmotorsport.com/resource-centre/tyre-applications/sae-formula-student Avon Tyres Formula Student]<br />
<br />
<br />
<br /><br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Dry==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
|Continental<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
|Goodyear<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| rowspan="9"|Hoosier <code><ref>https://www.hoosiertire.com/images/content/files/FormulaSAE19(1).pdf</ref></code><br /><br />
| <br />
|16.0 x 6.0-10<br /><br />
|~3.2kg<br /><br />
| <br />
| <br />
|-<br />
| <br />
|16.0 x 7.5-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|6.0/18.0-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 6.0-10<br />
|~4kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 7.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 6.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 7.5-10<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.5 x 7.0-13<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.0 x 7.5-13<br /><br />
|~5.4kg<br />
| <br />
| <br />
|-<br />
|Pirelli <br /><br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
==Wet==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
| rowspan="2"|Hoosier<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]<br />
<br />
=References=<br />
<code><references /></code></div>AGhttp://fswiki.us/index.php?title=File:Image20.png&diff=1603File:Image20.png2020-05-24T19:39:29Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image29.png&diff=1602File:Image29.png2020-05-24T19:38:03Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=Tires&diff=1601Tires2020-05-24T19:34:28Z<p>AG: /* Theory Stuff */</p>
<hr />
<div>Good smelling round things<br />
=Theory Stuff=<br />
[[G-g Diagram|G-g Diagram]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
Tires are rubber based, with metal cords to re-enforce the structure both on the contact face, and on the vertical “side walls”. They are most commonly pneumatic (i.e inflated with air), and the result is a substantially stiff rolling structure, with the rubber generating adhesion as well as mechanical “interlocking” with the asphalt, with the result being friction.Why do tires matter? Put simply, they are the only link of the car with the ground. While almost all systems are critical for the car operation, the tires have a special role in the car’s performance - a race-car generates forces and accelerations, both through driver inputs and engine power. In this way, the tires are essentially a “gate-keeper”, where the limit of force (and as such acceleration) has an upper limit. So, more engine power, or more brake power, is only helpful if the tires can handle it. Why is more acceleration better? On a race-track, better acceleration/deceleration in a straight line means higher top speed and later braking before the corner. In a corner, better acceleration means higher corner speeds for a given radius (a=v^2/r).<br />It gets more complex. The tire is not fully rigid. If it was, it would not be able to “store” energy and generate cornering force. It is best to think of it like a spring, and cornering forces generate a torsion around the vertical axis going through the tire centerpoint. The twist angle generated is called “Slip angle”.<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/d/db/Image34.png/300px-Image34.png" decoding="async" width="300" height="420" class="thumbimage" srcset="/images/thumb/d/db/Image34.png/450px-Image34.png 1.5x, /images/thumb/d/db/Image34.png/600px-Image34.png 2x"></a> <a class="internal" title="Enlarge"></a>Slip AngleAs the driver steers, the slip angle rises (and so does the cornering acceleration/force), but it does not do so linearly. This is a very important aspect of tire behavior.<br />
<br />
<br />
<br />
<br />
[[File:Image6.png|center|middle|thumb|Tire Comparison (fictional)]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/1/15/Image6.png/300px-Image6.png" decoding="async" width="300" height="343" class="thumbimage" srcset="/images/thumb/1/15/Image6.png/450px-Image6.png 1.5x, /images/thumb/1/15/Image6.png/600px-Image6.png 2x"></a> <a class="internal" title="Enlarge"></a>Tire Comparison (fictional)Another related aspect is “alligning torque”, which is the moment the tire exerts around its centerline to return to neutral position (pre-deformation, i.e zero slip angle). How would it generate a moment? Only if the cornering force acts at a distance from the centerline of the tire.<br />
<br />
<br />
[[File:Image8.png|center|middle|thumb|Pneumatic trail ]]Now, why is this important? Because, we are not very sensetive to accelerations - i.e, the driver cant just feel in his body that the car is at peak acceleration very accurately. As such, the feedback of the tires through the steering wheel is very useful.<br />
<br />
<br />
[[File:Image151.png|link=https://www.semanticscholar.org/paper/Modeling-%2C-Analysis-and-Control-Methods-for-Vehicle-Takahashi/3f1dc5d4f82dce2e5a25cf20d470bbe68d4bb2b3|center|middle|thumb]]<br />
<br />
<br />
This is where it should be noted that this torque is also non linear, relative to slip angle and to cornering force! What the driver would feel is increasing steering force, then gradually decreasing, while the car is still increasing in cornering force. This is due to the slippage of the contact patch changing location.<br />
<br />
<br />
<br />
<br />
Another factor is the tire’s relationship to vertical load - i.e, why heavier cars dont corner as well as lighter cars. Tires operate with both “adhesion” and “Hysteresis” that can also be called as “mechanical interlocking” on a macro scale with the asphalt. A sidenote - The adhesion is vastly reduced in the rain, but the Hysteresis is not affected.<br />
<br />
<br />
<br />
<br />
[[File:Image14.png|link=https://www.fhwa.dot.gov/publications/research/safety/14065/002.cfm|center|middle|thumb|Mechanisms of grip ]]<br />
<br />
<br />
Now, the coefficient of friction of the tire is unitless, and it is the single most important measure of tire performance - or at least, the easiest one to see at a glance. We were taught in highschool physics that this friction coefficient is constant, and independent of surface area. That is not true! On some materials it may stay very near constant. But on a rubber tire, the coefficient is actually negatively correlated to vertical load - load goes up, coefficient goes down. This is substantial enough to be the single biggest justification for making a race-car lighter.<br />Below, a primary reason for this behavior is seen. This is the macro level “interlocking” of the rubber with the asphalt, a very conventional friction model. As the vertical (i.e normal) load increases, the rubber expands to fill the road ridges, but it begins to saturate (i.e it cannot go any further into the asphalt).<br />
<br />
=List of Tires=<br />
[https://www.millikenresearch.com/fsaettc.html Formula SAE Tire Test Consortium]<br />
<br />
<br />
[https://www.hoosiertire.com/tires/circuit/spec/#panel-spec Hoosier Tires FSAE 2020]<br />
<br />
<br />
[http://www.avonmotorsport.com/resource-centre/tyre-applications/sae-formula-student Avon Tyres Formula Student]<br />
<br />
<br />
<br /><br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Dry==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
|Continental<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
|Goodyear<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| rowspan="9"|Hoosier <code><ref>https://www.hoosiertire.com/images/content/files/FormulaSAE19(1).pdf</ref></code><br /><br />
| <br />
|16.0 x 6.0-10<br /><br />
|~3.2kg<br /><br />
| <br />
| <br />
|-<br />
| <br />
|16.0 x 7.5-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|6.0/18.0-10<br />
|~3.6kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 6.0-10<br />
|~4kg<br />
| <br />
| <br />
|-<br />
| <br />
|18.0 x 7.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 6.5-10<br />
|~4.5kg<br />
| <br />
| <br />
|-<br />
| <br />
|19.5 x 7.5-10<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.5 x 7.0-13<br />
|~5kg<br />
| <br />
| <br />
|-<br />
| <br />
|20.0 x 7.5-13<br /><br />
|~5.4kg<br />
| <br />
| <br />
|-<br />
|Pirelli <br /><br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
==Wet==<br />
<br />
{| class="wikitable"<br />
|-<br />
|'''Make'''<br />
|'''Model'''<br />
|'''Size'''<br />
|'''Weight'''<br />
|'''Comments'''<br />
|'''TTC'''<br />
|-<br />
| rowspan="2"|Hoosier<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
|-<br />
| <br />
| <br />
| <br />
| <br />
| <br />
| <br />
|}<br />
<br />
<br />
[[Category:Suspension]][[Category:Vehicle Dynamics]]<br />
<br />
=References=<br />
<code><references /></code></div>AGhttp://fswiki.us/index.php?title=File:Image14.png&diff=1600File:Image14.png2020-05-24T19:33:21Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image151.png&diff=1598File:Image151.png2020-05-24T19:32:09Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image8.png&diff=1597File:Image8.png2020-05-24T19:30:29Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image6.png&diff=1596File:Image6.png2020-05-24T19:28:48Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image34.png&diff=1595File:Image34.png2020-05-24T19:27:16Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1594Tube Frame2020-05-24T19:21:32Z<p>AG: </p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="internal" title="Enlarge"></a><br />
<br />
<br />
<a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
[[File:image41.png|right|middle|thumb|Configuring Hinge Joints]]<br />
<br />
===Solid-Body Frame FEA (Soldworks)===<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1593Tube Frame2020-05-24T19:20:43Z<p>AG: /* Analysis */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<br />
<a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
[[File:image41.png|right|middle|thumb|Configuring Hinge Joints]]<br />
<br />
====<br />
===Solid-Body Frame FEA (Soldworks)===<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1592Tube Frame2020-05-24T19:19:56Z<p>AG: </p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<br />
<a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
<br />
<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
[[File:image41.png|right|middle|thumb|Configuring Hinge Joints]]<br />
====<br />
===Solid-Body Frame FEA (Soldworks)===<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1591Tube Frame2020-05-24T19:17:26Z<p>AG: /* Analysis */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow (Solidworks):===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<a class="image"><img alt="" src="/images/thumb/4/4d/Image41.png/300px-Image41.png" decoding="async" width="300" height="134" class="thumbimage" srcset="/images/thumb/4/4d/Image41.png/450px-Image41.png 1.5x, /images/thumb/4/4d/Image41.png/600px-Image41.png 2x"></a> <a class="internal" title="Enlarge"></a>"Hinge" Joint Configuration<br />
======<br />
======<br />
===Solid-Body Frame FEA (Soldworks)===<br />
<br />
Its not computationally realistic to do a solid body simulation for the entire frame. As such, I recommend exporting a section of interest, and ananlyzing it seperately. For example, the bellcrank mounting, or a-arm tabs. In the case of the bellcrank, you'd be best to include the actual bellcrank as well and perform an assembly simulation. You never know how much it will contribute!<br />
<br />
How to export a section? Start from having a fully merged body that includes the tubes/tabs of interest. The extruded tabs have to properly intersect the tube for merging to work. You can use the "combine" feature (just search for it in the command search box) to combine all the bodies together. Once done, right click the body, and click "insert into new part".<br />
<br />
Proceed with solid body FEA - NOT beam FEA. Meshing is sometimes tricky, so the addition of fillets as well as mesh control (mesh per part size) helps auto refine the mesh in the sharp edges and prevent the meshing from failing.<br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1590Tube Frame2020-05-24T19:08:08Z<p>AG: /* Solid-Body Frame FEA */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow:===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<br /><br />
<br />
[[File:Image41.png|right|middle|thumb|"Hinge" Joint Configuration ]]<a class="image"><img alt="" src="/images/thumb/4/4d/Image41.png/300px-Image41.png" decoding="async" width="300" height="134" class="thumbimage" srcset="/images/thumb/4/4d/Image41.png/450px-Image41.png 1.5x, /images/thumb/4/4d/Image41.png/600px-Image41.png 2x"></a> <a class="internal" title="Enlarge"></a>"Hinge" Joint Configuration<br />
<br />
===Solid-Body Frame FEA===<br />
[[File:Image75.png|none|middle|thumb|FEA setup ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/2/25/Image75.png/300px-Image75.png" decoding="async" width="300" height="131" class="thumbimage" srcset="/images/thumb/2/25/Image75.png/450px-Image75.png 1.5x, /images/thumb/2/25/Image75.png/600px-Image75.png 2x"></a> <a class="internal" title="Enlarge"></a>FEA setup<br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1589Tube Frame2020-05-24T19:07:55Z<p>AG: /* Analysis */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
<br />
<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow:===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
# [[File:image75.png|right|middle|thumb|FEA setup ]]Run, then view results! to understand if it makes sense, animate it - with the stress view.<br />
<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<br /><br />
<br />
[[File:Image41.png|right|middle|thumb|"Hinge" Joint Configuration ]]<a class="image"><img alt="" src="/images/thumb/4/4d/Image41.png/300px-Image41.png" decoding="async" width="300" height="134" class="thumbimage" srcset="/images/thumb/4/4d/Image41.png/450px-Image41.png 1.5x, /images/thumb/4/4d/Image41.png/600px-Image41.png 2x"></a> <a class="internal" title="Enlarge"></a>"Hinge" Joint Configuration<br />
<br />
===Solid-Body Frame FEA===<br />
<br />
[[File:Image75.png|none|middle|thumb|FEA setup ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/2/25/Image75.png/300px-Image75.png" decoding="async" width="300" height="131" class="thumbimage" srcset="/images/thumb/2/25/Image75.png/450px-Image75.png 1.5x, /images/thumb/2/25/Image75.png/600px-Image75.png 2x"></a> <a class="internal" title="Enlarge"></a>FEA setup<br />
<br />
<br /><br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1588Tube Frame2020-05-24T19:04:40Z<p>AG: </p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===Torsional FEA (Beam sim) Workflow:===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
[[File:image75.png|right|middle|thumb|FEA setup ]]Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<br /><br />
<br />
[[File:Image41.png|right|middle|thumb|"Hinge" Joint Configuration ]]<a class="image"><img alt="" src="/images/thumb/4/4d/Image41.png/300px-Image41.png" decoding="async" width="300" height="134" class="thumbimage" srcset="/images/thumb/4/4d/Image41.png/450px-Image41.png 1.5x, /images/thumb/4/4d/Image41.png/600px-Image41.png 2x"></a> <a class="internal" title="Enlarge"></a>"Hinge" Joint Configuration<br />
<br />
===Solid-Body Frame FEA===<br />
[[File:Image75.png|none|middle|thumb|FEA setup ]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/2/25/Image75.png/300px-Image75.png" decoding="async" width="300" height="131" class="thumbimage" srcset="/images/thumb/2/25/Image75.png/450px-Image75.png 1.5x, /images/thumb/2/25/Image75.png/600px-Image75.png 2x"></a> <a class="internal" title="Enlarge"></a>FEA setup<br />
<br />
<br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1587Tube Frame2020-05-24T19:02:51Z<p>AG: /* Analysis */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:[[File:Image152.png|right|middle|thumb|Torsional stiffness FEA in solidworks]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/0b/Image152.png/300px-Image152.png" decoding="async" width="300" height="176" class="thumbimage" srcset="/images/thumb/0/0b/Image152.png/450px-Image152.png 1.5x, /images/thumb/0/0b/Image152.png/600px-Image152.png 2x"></a> <a class="internal" title="Enlarge"></a>Torsional stiffness FEA in solidworks<br />
<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined below)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
===<br />
<br />
Torsional FEA (Beam sim) Workflow:===<br />
<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
[[File:image75.png|right|middle|thumb|FEA setup ]]Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<br /><br />
<br />
[[File:Image41.png|right|middle|thumb|"Hinge" Joint Configuration ]]<br />
===Solid-Body Frame FEA===<br />
[[File:Image75.png|none|middle|thumb|FEA setup ]]<br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=File:Image41.png&diff=1586File:Image41.png2020-05-24T19:02:33Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image75.png&diff=1585File:Image75.png2020-05-24T18:59:06Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Image152.png&diff=1584File:Image152.png2020-05-24T18:55:03Z<p>AG: </p>
<hr />
<div>(Note - simplified model for tutorial purposes, not a rules legal frame)</div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1582Tube Frame2020-05-24T18:51:59Z<p>AG: </p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined here)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
Torsional FEA Workflow:<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<br /><br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1581Tube Frame2020-05-24T18:47:09Z<p>AG: /* VR3 Engineering - Specifics */</p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
<br />
<br />
[[File:image16.png|right|middle|thumb]]<br />
<br />
<br />
<a class="image"><img alt="Image16.png" src="/images/thumb/9/9d/Image16.png/300px-Image16.png" decoding="async" width="300" height="201" class="thumbimage" srcset="/images/9/9d/Image16.png 1.5x"></a> <a class="internal" title="Enlarge"></a><br />
<br />
<br />
<br />
Their machine has a vertical mill head (1/8in diameter) and a rotating feeder cuff. This means that in the default 3-axis configuration (and for round tubes), the end-mill is always perpendicular to the tube surface being cut. This matters for tolerances/fit:<br />
<br />
<br />
<br />
<br />
You can request them to use the 4th axis on round tubes where a very tight tolerance is required. For the Ryerson 2020 car, we asked for it on the a-arm tubes, which are .5in diameter.But for all other frame tubes, it is of no consequence, the tube will still fit very well, as intended.<br />
<br />
<br />
<br />
<br />
[[File:Image99.png|right|middle|thumb|3 vs 4 axis ]]<br />
<br />
<br />
<a class="image"><img alt="" src="/images/thumb/0/03/Image99.png/300px-Image99.png" decoding="async" width="300" height="305" class="thumbimage" srcset="/images/thumb/0/03/Image99.png/450px-Image99.png 1.5x, /images/0/03/Image99.png 2x"></a> <a class="internal" title="Enlarge"></a>3 vs 4 axis<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined here)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
<br />
Torsional FEA Workflow:<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<br /><br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=File:Image99.png&diff=1580File:Image99.png2020-05-24T18:46:22Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=File:Imag15.png&diff=1579File:Imag15.png2020-05-24T18:38:36Z<p>AG: </p>
<hr />
<div></div>AGhttp://fswiki.us/index.php?title=Tube_Frame&diff=1578Tube Frame2020-05-24T18:38:01Z<p>AG: </p>
<hr />
<div>[[Category:Chassis]]<br />
<br />
<br />
<br />
A tube frame or space frame is a chassis constructed from rigid truss members attached in a three-dimensional structure with the body panels having little or no structural function. Stiffness is maximised by triangulating the tubing to ensure that the tubes are not loaded in bending.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
==Design==<br />
Designing the tube frame is a compromise between structural rigidity, weight and manufacturing complexity.<br />
===Triangulation===<br />
Proper triangulation makes sure that the tubes are not loaded in bending. Full triangulation is probably impossible given that the driver like, can't have a frame member through their torso, but please try?<br />
==Manufacturing==<br />
Many teams use "VR3 Engineering" to produce their tubeset. This is an all inclusive (bending and cutting) service, and will be in the 3000-5000$ range for frame and suspension, depending on complexity and shipping. The upside is substantial time saved - their process is nearly fully automated, and the manufacturing process limits are fairly minimal.<br />
===Cutting tubes===<br />
Tubes can be cut by hand, using holesaws and a drill press, or by using water jet or laser jet cutting.<br />
===Tube bending===<br />
Bending the tubes by hand<br />
<br />
<br />
<br />
<br />
Using CNC tube benders<br />
<br />
<br />
<br />
Any motorcycle builders around? They can have tools for 1" tubing.<br />
<br />
<br />
<br />
<br />
===VR3 Engineering - Specifics===<br />
This is a schematic of the tube cutting setup:<br />
<br />
<br />
<br />
<br />
===Fixtures===<br />
Fixturing is central to the accuracy of the finished tube frame. Fixtures can be made in MDF, plywood or sheet metal.<br />
===[[Welding|Welding]]===<br />
==Analysis==<br />
Goal:<br />
* To test totsional rigidity, camber (lateral) rigidity, and perhaps also toe rigidity<br />
* To stiffen frame where needed, and change up layouts<br />
* To make sure it doesnt break, or is too close to low FOS where welds may crack<br />
* Frequency analysis perhaps?<br /><br />
<br />
Problem:<br />
* Solid body FEA with a triangle mesh is too time consuming, for a 50+ tube frame. IF you have to, export small sections and do a small contained study (outlined here)<br />
* Theres a quicker method - beam FEA. It makes a mesh of “pie cuts” of tubes. Way less mesh data, but very good accuracy still - a whole frame sim can run in ~30sec, on a laptop.<br />
* It does not capture tab interfaces etc, but it does caputre member stresses.<br />
* Cannot do an assembly simulation in it, but can simulate pivotable “joints”<br />
<br />
<br />
Torsional FEA Workflow:<br />
# Put in a mock “engine” as just a bunch of tubes, triangulated to be stiff.<br />
# Put in mock a-arms (lower arms only, upper arent needed unless doing camber stiffness) and pushrods<br />
# Modify the appropriate joints to “hinges” (by right clicking on a member in the cutlist folder in the tree, and clicking "edit definition")<br />
# Apply “immovable (allowing rotation) fixtures to 3 wheel, apply 100lb upwards to the 4th.<br />
# Bellcrank can be done but its complex computationally and my best way was to treat as direct actuation (getting decently accurate), and then performing a separate exported section get simulated with an assembly simulation - with the actual bellcrank, tabs etc. Then just add up the two deflections.<br />
Beam FEA Notes:<br />
* Beam FEA doesnt like short members. If you have a short member, ask yourself if it can be “combined” (i.e combine operation) with another. An example is suspension tabs. In our case, they will be combined with the arm tubes.<br />
* Beam FEA also doesnt like arcs - sharper bent tubes (making arcs that are fairly long, like 3inch plus) as nodes should be avoided, as ive had a bunch of weird bugs in FEA where the SIM node of the RRH being an arc just randomly detached<br />
* Beam FEA works with “nodes” that it automatically computes. You can get it to manually compute, based on custom set distances - this helps eliminate (filter out) 2 super close together nodes. But keep in mind, every time you recompute the nodes, your fixtures may change - since their referenced node will change number.<br />
<br /><br />
<br />
==Frame/Susp - Sending out==<br />
If using VR3 engineering to produce your tubeset for you, you have to send out a:<br /><br />
* BOM Drawing<br />
* VR3 template excel sheet, with a qtys summary<br />
* Once quote approved, indiv tube files.<br />
<br />Fortunately, a superb guide already exists - on the VR3 website. Its not a super light/easy thing to figure out, and yes you will have some late nights (or one all nighter) trying to send the frame out - usually, due to struggling with the BOM etc - but what do you expect? Not everything in life is a light read.<br />The doc is “SAE Student Guideline”, and is in their documents section of [https://vr3.ca/technical-documents/ their website]<br />
<br /><br /></div>AGhttp://fswiki.us/index.php?title=File:Img15.png&diff=1577File:Img15.png2020-05-24T18:37:45Z<p>AG: </p>
<hr />
<div></div>AG