Torsional Test of Frame

[Popeye]

Do people agree with the train of thought that there is a torsional stiffness of the frame and a torsional stiffness of the entire vehicle/suspension as a whole? It would be my impression that there would be four more significant outcomes of physical testing.
1-validate FEM by simply replicating constraints and loading conditions in reality with those used in a FEM package.
2-determine the torsional stiffness of the frame alone between the bell cranks
3-determine the torsional stiffness of the frame and all suspension components to determine expected "slop" of suspension components (using solid pieces in place of shocks, loaded through uprights with all pushrods, bellcranks and a-arms in place)
4-to improve vehicle simulations in adams with respect ot roll center position and overall vehicle response.

Lastly, why would one want to constrain their vehicle at the main roll hoop as it is not going to replicate accurately the load paths through the chassis as would be seen during vehicle use.

Regards,

Pops

[Popeye]

Do people agree with the train of thought that there is a torsional stiffness of the frame and a torsional stiffness of the entire vehicle/suspension as a whole? It would be my impression that there would be four more significant outcomes of physical testing.
1-validate FEM by simply replicating constraints and loading conditions in reality with those used in a FEM package.
2-determine the torsional stiffness of the frame alone between the bell cranks
3-determine the torsional stiffness of the frame and all suspension components to determine expected "slop" of suspension components (using solid pieces in place of shocks, loaded through uprights with all pushrods, bellcranks and a-arms in place)
4-to improve vehicle simulations in adams with respect ot roll center position and overall vehicle response.

Lastly, why would one want to constrain their vehicle at the main roll hoop as it is not going to replicate accurately the load paths through the chassis as would be seen during vehicle use.

Regards,

Pops

[DJHache]

I agree with your first three points, but I'm not clear about your fourth one? How do you tie into ADAMS and vehicle performance?

As for the pulling from the roll hoop, I think it might be interesting if you were to put scales under each of the four tires. From a kinematic/WT point of view, lateral accel is just a force through a specific point (the cg). The suspension, tires, and everything else don't care about where the force is coming from, as long as the magnitude of the force and the roll angle of the chassis, as well as the moments are the same. I think you could perform some very interesting static tests to simulate dynamics...

[Popeye]

With regard to my fourth point I was referring to the instance where the frame stiffness was known, it could be put into the adams model of the vehicle thus the suspension can be designed with a frame which deflects under load as does the real one.

I may be more clear but I may still be wrong....

Pops