Torsional Rigidity on FEA

[Erick Scarpone]

Is this ok? We got the Angular deformation, we know the magnitude of the force and the distance from the center of the plane were the forces are being applied to the actual place were the forces are applied.
We are getting really low numbers so we definitely now that last years frame suck, we just want to know if we are doing it right thanks!

[Erick Scarpone]

Is this ok? We got the Angular deformation, we know the magnitude of the force and the distance from the center of the plane were the forces are being applied to the actual place were the forces are applied.
We are getting really low numbers so we definitely now that last years frame suck, we just want to know if we are doing it right thanks!

[Denny Trimble]

Let me guess, 800 ft-lbs/deg? Not much triangulation there except for one side impact tube on each side.

It looks like you're applying all your loads and constraints at the a-arm pickup locations. You should look into modeling how the forces are actually applied from the springs to the chassis (through the rocker arm pivots and shock mounts).

The problem with fixing your rear upper and lower points is that it stiffens the rear box structure artificially. Make sure you look at the animations to see how your frame is flexing.

[Erick Scarpone]

Your guess pretty much right, what should we do restrict the rear box only at the top/ bottom thanx
I thought i should aplied the forces on the A-Arms mounts, should i add the forces on the spring ans schocks or just do it at the springs and shocks? Would in be the same to aplied at the bellcranks?

[Erik Whoa]

You need to fix the frame at 3 of your suspension pivots. The remaining pivot has a force applied to it. Basically, a torque is applied to the frame. You can find SAE papers on this subject.

If you want to stiffen up your frame, I would try increasing its moment of inertia in certain sections. That's all I can tell you. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[mtg]

Read this:

Chassis Design Paper (http://campus.umr.edu/fsae/library/sae_paper/paper.html)

That should give an idea on how to go about improving the frame.

[Erick Scarpone]

thanks a lot mtg thats a really good paper, but does anyone have pictures of their chassis with the restrictions and the loads, lots of people have send me info on this subject but they all difer on something

There people that think it is best to get the loads and restriction directly on the suspension points

And othersw that to put it directly on the wheel rotors and other elements.

I have tried both but in Cosmos putting it on the wheel is to computer ineficient it takes hours and many time computer crashes.

I'm thinking of a way of doing a universal torsional rigidity tester so I can take it to detroit and test everyones car on it, but there are also so many ways to go wrong with this tester...

At some point I'll have to buil a torsional rigidity bench and compere results with the computer. And find out what im doing wrong either on the computer or on the bench