opensus
Suspension load cases and link loads
The Loads tab runs a list of design load cases and keeps the worst force each link, pushrod, spring, ball joint and pivot bearing sees, with the case and corner that caused it. Those are the loads to size tubes, rod ends, bearings and brackets for.
Default load cases
| Case | Kind |
|---|---|
| 2 g lateral + 2 g braking | Static |
| 1 g acceleration + 5 g bump | Static |
| Pure cornering, 2 g | Static |
| Pure acceleration, 1 g | Static |
| Pure braking, 2 g | Static |
| Pure bump, 3 g | Static |
| 1.5 g cornering + 3 g bump | Static |
| Kerb strike, 20 m/s | Transient |
| Bump across the track, 25 m/s | Transient |
| Trail braking into a corner | Transient |
Every case can be edited, switched off, or added to, and the list is saved with the design.
How the loads are found
Static cases take weight transfer and suspension position from the full-car model. Each tire then carries lateral g times its load, and braking or drive is split by brake bias or drive split and then by load across each axle, so tire grip never caps a design case. A bump factor sets each wheel's vertical load to a multiple of its static load, carried by the spring and bump stop.
Transient cases simulate the event through time with springs, dampers, sway bars and tires, then solve the linkage at every step (about 400 per case), so damper forces and the unsprung mass's inertia are included.
At each instant every corner is solved as rigid links with the springs as members and the dampers and sway bar as known forces. Inboard brakes and drive apply their longitudinal force at the wheel center.
Reading the results
- Links, pushrods, toe links and springs carry axial force: tension and compression are reported separately, so you can check compression members for buckling.
- Ball joints and pivot bearings report the largest force through them in any direction.
- Each value names the case and corner that caused it. Hover a row to see the part in 3D.
On the Formula SAE example the most heavily loaded part is the front lower arm's rear inner pivot, at about 9.9 kN in 2 g lateral + 2 g braking.
Checks behind it
Feeding the tire model's own forces into the linkage solver, the spring force it finds matches the full-car model's spring force to within 0.05 % at every corner, in cornering, braking and combined cases. See validation.
Limits
Links are rigid; no safety factors or fatigue are applied; loads on the upright and brake caliper themselves are not included. Left and right are combined for each axle.