Worst Case Loadings

[Ballzac]

What kind of forces are people using for worst case scenerio loadings at the tire contact patch to do upright/hub/control arm FEA analysis? I've been playing around with an upright design in FEA with 500 lbs in each direction (x,y,z) acting on the center of the upright where the spindle would transmit the forces while constraining the upper and lower ball joints (Haven't looked into applying moments in CosmosWorks yet). Can anyone with more experience in this area give any suggestions?

Thanks.

[Ballzac]

What kind of forces are people using for worst case scenerio loadings at the tire contact patch to do upright/hub/control arm FEA analysis? I've been playing around with an upright design in FEA with 500 lbs in each direction (x,y,z) acting on the center of the upright where the spindle would transmit the forces while constraining the upper and lower ball joints (Haven't looked into applying moments in CosmosWorks yet). Can anyone with more experience in this area give any suggestions?

Thanks.

[Denny Trimble]

Ballzac,
You should try a remote load in Cosmos. Basically, you have to define a coordinate system at the tire contact patch, then you can apply loads through the contact patch to the spindle (or whatever else you want to). Restrain the ball joints appropriately (spherical, not fixed), and you can get reaction forces that you can then use to analyze the control arms.

Mike T could tell you more about exactly what numbers we use, but generally I think it's a 2/2/3 G (lateral/braking/vertical) load case with a 2.0 factor of safety minimum on the structure. You'll have to calculate load transfer to get the actual forces on each contact patch in each situation.

Also, don't forget to look at stiffness. For the upright, you can find the forces on the balljoints as I said above, then fix the spindle and apply those forces in another study. Find the displacements at each balljoint, and you have upright stiffness.

I don't think you can directly find displacement of the contact patch used in the remote load in the first case, but if you can, let me know.

-Denny