Extracting total contact force in dynamic implicit analysis

AmirMar

Dear all,

As for now it is impossible to extract contact forces in implicit dynamic analysis using CONTF. However, FORCE/ELFORCE (elemental force) is still available.
Is there a way to extract the temporal contact forces using FORCE on shell elements which may be in frictional contact some time during the analysis?

Thank you,
Amir

Adriano A. Koga

just ot make sure, what kind of dynamic analysis are you performing? FRF? Transient?

 

OS allows linear contact only in FRF/Linear Transient, with no Friction. That means frictionless contact, depending only on the initial contact status, with no open/close behavior change.

 

If you really want friction in contact for dynamics, you would need to run a NLTransient analysis, that offers you CONTF output. (but for sure, more expensive).

I hope this helps you.

AmirMar

Hi Adriano,

Thank you for the fast reply.
I was reffering to both linear direct and nonlinear contact actually.
I browsed the documentation, under Reference Guide->Output Data->Results Output by OptiStruct->Transient Analysis Results

and CPNTF is absent from the table.. I couldn't see any distinction between linear and nonlinear transient analysis in this article.
If you say that nonlinear transient dynamic analysis should allow to extract CONTF then the documentation should reflect this.

Regarding linear transient analysis: even though only linear contact is allowed there (no contact change) then contact forces may still arise in bonded contact.
Is it possible to extract them?

Thank you,
Amir

Adriano A. Koga

I believe the missing CONTF in the help means that it is not available under linear transient, as it is a typical NL result. Never tried CONTF with linear contacts.( Slide or FREEZE).

I honestly don't know if you're able to extract this information from linear.

 

I bbelieve there is a separate section for NL Transient analysis, if i recall it correct, and I hope that CONTF is present there.

 

 

 

AmirMar

Thank you Adriano.

If you, or any other user, has some idea on how to workaround this limitation and derive the contact force using FORCE/ELFORCE in linear transient analysis then I'll be happy to know.