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Excessive stres peaks around bolt head

Experimenter
Experimenter

Hi all,

 

I'm at a total loss! Attempting to run a simulation of a simplified engine block. Basically two parts bolted together on which to put a bolt preload and a bearing force. The parts are glued together. 

 

In this simulation I only have the bolt preload (40Kn) applied. The bolt is made using the standard CBAR and RBE3 elements. Mesh around the "affected" area has been sized down to 0,5mm using mesh control. For some reason I keep getting extremely high stress peaks around the head of the bolt. 

 

What could I change to prevent these peaks?

 

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3 REPLIES

Re: Excessive stres peaks around bolt head

Siemens Phenom Siemens Phenom
Siemens Phenom

It looks like your RBE3 only connect to the edge of the hole. If so, the stress will keep increasing as the mesh size decreases.

 

You should split the face around the head to define a washer contact patch, then connect the RBE3 from the CBAR to all of the nodes on the patch face.

Re: Excessive stres peaks around bolt head

Experimenter
Experimenter
The spider diameter is set to 17mm whereas the hole is 10mm. But I will definetly give it a try tommorow! Thanks for the tip, will keep you posted.

Re: Excessive stres peaks around bolt head

Experimenter
Experimenter

So I split the face to create 17mm wahser contact patch. However with the bolt spider connected to that I still got similair results. Tried it with both a CTETRA mesh and using a CQUAD8 shell (with several different materials assigned) on the washer patch. 

 

Any other suggestions that might fix this?