Bolts/Compression only elements

Altair Forum User

Hey,

I need to model a bolt/pin in a 3D structure. I have been using RBE2 elements (this is the way the bolt connector does it to correct?), however my problem is that if I bolt 2 parts together the bolt in reality should exert a bearing force on the connected parts. However the RBE2 elements naturally push on one side of the hole and pull on the other side, this pulling action is unrealistic.

Does anyone know how to better specify a bolt, or to set the rigid elements to be compression only?

Thanks

Altair Forum User

JobMan,

It looks more like OS/NASTRAN/?? question rather than HM.

If your solver would be ABAQUS I could help you.

But.. generaly speaking, instead of having rigid spokes (RBE2) you need to have spokes with compressive stiffness and no tensile stiffness (plus two fixed rotational DOF) It can be done by using set of nonlinear spring elements or (in ABAQUS) connectors.

I have made a macro for abaqus some time ago - it creates 'star' of connector elements with compressive stiffness only. It works very well and saves a lot of CPU time (I repleaced contact with this simplified definition) Stress distribution nearly identical to full 3d connection model)

Good luck.

Souaveck