Difference between revisions of "Compliance"
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| − | == Compliance | + | ==Compliance Calculation Applied to Suspension== |
| − | For example, every tire has an ideal camber angle for maximum lateral force generation. However, as force is generated the suspension will strain and deform, so this angle cannot be realistically maintained. It follows then that in addition to targeting a specific angle, it is also wise to define a maximum tolerable deviation from this angle (or rather a maximum tolerable grip loss), or a maximum "compliance" in the suspension, e.g. 1° at 1G lateral. This angle can then be further divided into the various components of the suspension e.g. 0.1° in the upright, 0.05° in the bearings, 0.1° in the hub and 0.2° in the rim etc. Now we have a concrete target for the respective components to be judged against. | + | For example, every tire has an ideal [[camber angle]] for maximum lateral force generation. However, as force is generated the suspension will strain and deform, so this angle cannot be realistically maintained. It follows then that in addition to targeting a specific angle, it is also wise to define a maximum tolerable deviation from this angle (or rather a maximum tolerable grip loss), or a maximum "compliance" in the suspension, e.g. 1° at 1G lateral. This angle can then be further divided into the various components of the suspension e.g. 0.1° in the upright, 0.05° in the bearings, 0.1° in the hub and 0.2° in the rim etc. Now we have a concrete target for the respective components to be judged against. |
Naturally we generally want to minimise suspension compliance, but as with everything, this cannot be done without compromises (e.g increased weight). | Naturally we generally want to minimise suspension compliance, but as with everything, this cannot be done without compromises (e.g increased weight). | ||
| − | == Example of | + | ==Example of Compliance Minimisation== |
A popular type of roast on various FS forums is pictures of suspension points mounted on a tube, away from any nodes. This violates the central rule of truss structures (two-force members only, see [[Tube Frame]]) and will result in dis-proportionate amounts of compliance as the tube bends. Reacting the suspension forces at nodes will make the assembly much stiffer at minimal cost. | A popular type of roast on various FS forums is pictures of suspension points mounted on a tube, away from any nodes. This violates the central rule of truss structures (two-force members only, see [[Tube Frame]]) and will result in dis-proportionate amounts of compliance as the tube bends. Reacting the suspension forces at nodes will make the assembly much stiffer at minimal cost. | ||
| + | |||
| + | == See Also == | ||
| + | [[Bearings]] | ||
| + | |||
| + | [https://www.reddit.com/r/FSAE/comments/kr6guf/compliance_estimation/ Reddit Discussion with Bill Cobb] | ||
| + | |||
| + | [https://www.researchgate.net/publication/289973663_Compliance_and_Friction_in_Elastic_and_Mechanical_Joints_of_Race_Car_Suspensions Zipfel George Compliance and Friction in Elastic and Mechanical Joints of Race Car Suspensions 2006] | ||
[[Category:Vehicle Dynamics]] | [[Category:Vehicle Dynamics]] | ||
Latest revision as of 13:04, 18 January 2021
Compliance is the inverse of stiffness. It might seem a bit backwards at first, but perhaps becomes more intuitive when you consider "compliance budgets" (mainly considered in vehicle dynamics/suspension, but occasionally applicable to other systems).
Compliance Calculation Applied to Suspension
For example, every tire has an ideal camber angle for maximum lateral force generation. However, as force is generated the suspension will strain and deform, so this angle cannot be realistically maintained. It follows then that in addition to targeting a specific angle, it is also wise to define a maximum tolerable deviation from this angle (or rather a maximum tolerable grip loss), or a maximum "compliance" in the suspension, e.g. 1° at 1G lateral. This angle can then be further divided into the various components of the suspension e.g. 0.1° in the upright, 0.05° in the bearings, 0.1° in the hub and 0.2° in the rim etc. Now we have a concrete target for the respective components to be judged against.
Naturally we generally want to minimise suspension compliance, but as with everything, this cannot be done without compromises (e.g increased weight).
Example of Compliance Minimisation
A popular type of roast on various FS forums is pictures of suspension points mounted on a tube, away from any nodes. This violates the central rule of truss structures (two-force members only, see Tube Frame) and will result in dis-proportionate amounts of compliance as the tube bends. Reacting the suspension forces at nodes will make the assembly much stiffer at minimal cost.
See Also
Reddit Discussion with Bill Cobb
Zipfel George Compliance and Friction in Elastic and Mechanical Joints of Race Car Suspensions 2006
