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Bolts with shell elements

Bolts with shell elements

Bolts with shell elements

(OP)
Hi,
I would like to model bolt connection between two shell plates with zero distance between. For solid modelling I use bar element with RBE2 (6 dof). I made simple model and compare results for independent node (RBE2) connecting two holes and with short bar element - results are very similar.
What should be choice for that ?

Regards,
Greg

RE: Bolts with shell elements

In Nastran you can use a CBUSH element.  

RE: Bolts with shell elements

I'd use a zero length spring, CELAS2 i think.  this allows you to control the stiffness of the fastener; an infintiely stiff RBE element will suck up all the load.  You can get fastener stiff estimates from Michael Niu's book.

RE: Bolts with shell elements

I agree with rb1957, I'd use 6 properly sized springs.
This is also useful if you need to estimate forces passing through the connection.

Regards

DS

'Ability is 10% inspiration and 90% perspiration.'

RE: Bolts with shell elements

A CBUSH is just that.  6 CELAS elements.  It would also handle any small seperation between the nodes.

RE: Bolts with shell elements

If you happen to have load-deflection data for your joint, the CBUSH element can be used with PBUSHT and TABLED1 cards in a nonlinear run.

The hard part is getting the load-deflection curve.

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