Problem with linear contact

[ander_ubi]

Hello.

I have created a contact between the outer surface of a pin and the inner surface of a shocket where it is housed. The problem is that in the deformation of the static analysis it can be seen that the mesh of the pin penetrates the mesh of the shocket and does not respect the contact. At the point where the meshes should contact, they penetrate and I get no stresses, and on the opposite side, where the meshes do not contact, I get the highest stresses. I don't understand what is happening. It is a linear contact with a friction coefficient and the model is made with hexahedron elements.

The property of this contact is used for other contacts in the model and there are no problems, but in the contact I have explained it does not respect it. Does anyone know what it could be?

I can't give you screenshots as it's a confidential project, sorry.

 

[dmapguru]

Which version of Nastran are you using?

 

[ander_ubi]

I use the FEMAP 2022.1 MP2 version. I think the problem may be due to the Inital Penetration configuration.

 

[dmapguru]

That's the pre-post. Am I to infer that you are using Siemens NX Nastran, or do you solve the problem in MSC Nastran?

 

[ander_ubi]

I don't know where this information appears. I do everything with Femap

 

[ThomasH]

If you do everything in Femap I think NX Nastran is a pretty safe bet. NX Nastran is often integrated into Femap.

 

[BlasMolero]

Dear Ander,
In general the problem is graphical, this is a very topic problem related with the scale of deformation used: activate ACTUAL DEFORMATION and use an scale 1:1, this way you will see the real deformation in the model. If the parts touch each other and the contact definition is well done you wwill not see penetration.
Please note in LINEAR CONTACT problems all parts will be touching each others in the assembled position: no gap is possible, this is linear contact, the solver Simcenter NASTRAN only computes the stiffness matrix at the iniitial position, not like in a genuine nonlinear snalaysis that updates the stiffness matrix at every time step, OK?. If you have gaps, the results are simply colors ....
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

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