Greetings!

This post is in continuation with our previous post about 'Design of Suspension and Steering System for a Formula Student Car (FSAE) using 3DEXPERIENCE Platform'.

The suspension system should be designed in such a way that it provides maximum contact of tyres with the road surface which ensures maximum tyre grip. The parameters to be considered while designing a suspension system include camber change rate, roll centre displacement and front view swing arm length(FVSA) in bump/droop and roll. Some of the important parameters on which the tyre grip depends are tyre pressure, camber, rim width and tyre temperature. Out of these, we can control the camber of the tyres through suspension system geometry. The variation of tyre grip with camber is as shown in the following graph:

This graph shows that the tyre grip is maximum when camber angle is 0 degrees or close to 0 degrees. Based on the above interpretation, camber value of all tyres in various situations should be kept close to 0 degree.

What is Bump/Droop and Roll?

For a Formula SAE car, we have to particularly consider camber value in maximum bump/droop and maximum roll while designing the suspension system. Bump (or Jounce) describes the upwards movement of the wheel occurs when the wheels hit a bump on the track surface whereas droop (or rebound) describes the downwards travel of the wheel occurs when the wheels drop into a depression in the track surface.  Also, Body roll (or lean) happens when you turn into a corner. As your car begins to turn, its weight is thrown to the outside of the corner, causing your car to roll in that direction.

According to the latest FSAE rules, minimum wheel travel should be equal to 50 mm. based on this, we have selected maximum bump and droop value as 25 mm each. Along with that camber in maximum 3 degree of roll is considered while designing the suspension system.

Apps Used:

Initially, we started with assumed hard points as discussed in the earlier post. The hard points are iterated such that the value of camber in maximum bump droop and roll comes as close as possible to 0. These iterations can be carried out by either using simple 2D sketch (CATIA Part Design ) or a program.

We have used CATIA Dymola Behavior Modeling to carry out iterations and along with that we have also used CATIA Part Design  to create 2D sketches. The template of the VeSyMa suspension library from CATIA DBM is used to carry out these iterations. A detailed explanation of this process will be stated in the further upcoming posts.

Students Involved:

@AK 

@VP

@PP

@KK

Earlier Posts:

Edu ​​​​​​​3DEXPERIENCE Community Knowledge​​​​​​​ Work Showcase ​​​​​​​