Inertia relief method: problem with PROD

Altair Forum User

Hi,

 

We try to optimize a monocoque structure for our race car. Therefore we need two loadcases: one for the torsional stiffness and one for the applied suspension loads. To check are model we tested both loadcases separately without any problems. For the suspension loads we used the inertia relief method:

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we used the PARAM INREL -2 and got reasonable results:

 

To check the torsional stiffness we need to add the wishbones. We modeled them with PROD's:

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When we do an analysis with both loadcases we got good results for the torsional stiffness but we got really large compliance for the suspension loads:

 

Is it possible to implement the inertia relief method on a combination of PCOMPP and PROD structures? Or are there possible other mistakes in our model?

 

Many thanks,

Jan

Rahul Rajan_21763

Hi,

 

I request you to give a try with beam element instead of rod element.

 

Regards

Rahul R

Altair Forum User

Altair Forum User said:

Hi,

 

I request you to give a try with beam element instead of rod element.

 

Regards

Rahul R

 

Thank you! Changing the rod elements indeed solved the problem. Is their also the possibility to exclude these elements of the analysis for a specific loadstep?

Rahul Rajan_21763

Hi,

Thanks for the update that the beam element worked in your case.

Rod mainly we use whenever structure is subjected to axial load & i believe beam is the right element type for your case.

Regards

Rahul R