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Bearing Connector versus Bearing Fixture -- 1/3 stress value?

Question asked by Kyle Huck on Dec 3, 2014
Latest reply on Dec 18, 2014 by Jared Conway

I am performing an analysis on a simple shaft supported by 2 bearings.  I first performed the analysis on only the shaft model using bearing fixtures.  I created split faces on the shaft where the bearings were located and where the loads were applied.  The bearing fixtures are both self-aligning and one bearing fixture prevents shaft rotation.  I put mesh a fine mesh control in the corner radii of the shaft where I expect high stresses (5 elements across corner radius).  My stresses and deflection seemed reasonable.  Also the animated deflection appeared to be correct in how the part deforms.  When I tried to get resultant forces on the bearings, it showed all zeros.

 

I setup the analysis again as an assembly with simple bearings and the shaft.  I used bearing connectors this time, both self-aligning and one preventing shaft rotation.  I also setup a no penetration contact set between the shaft and bearings.  I fixed the bottom of the bearing housings.  Again the animated displacement appears correct and the part is deforming properly.  However, the stress in the shaft is roughly 1/3 as much as when I ran the analysis with bearing fixtures.

 

 

The deformation is very similar but slightly different in the 2 studies as well.  When I used bearing connectors, the bearings do deflect and the shaft pulls away from the bearing race just slightly as expected.

 

I've attached a picture showing the 2 results and setup.  Thank you for your help!

 

Shaft Results.png

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