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Beam Bending Stress (Ms/Ss, Mt/St) vs. Render Beam Profile

Question asked by Jason Smith on Oct 20, 2016
Latest reply on Oct 29, 2016 by Jason Smith

In order to verify beam simulation results on a simply supported beam vs. hand calculations, I'm modeling a piece of 3" x 3" x 3/16" angle iron, 120" long with 3 loads of 100lb each located at the centroid 30" apart, but acting on an inner face. When I run the simulation and "render beam profile" with bending stresses in DIR1 and DIR2 directions, the results are dead on to my hand calcs. But when I plot the "Bending Stress in DIR1" and "Bending Stress in DIR2" directions without "render beam profile", I get results which don't resemble anything I've calculated. Sometimes they are 2-3x higher, sometimes lower, depending on the model.

 

In my model, the 100lb loads only cause a bending moment applied about DIR 2, the shear and bending diagrams in both DIR1 and DIR2 match hand calculations. The beam is restricted from rotation at its end faces, but can translate at one end.  According to the help file, my assumption would be that solidworks is plotting the max tensile fiber stress at an element cross-section when I don't "render beam profile". In my case, that should be 12699 lbf/in2 at max moment about DIR2, and solidworks plots this as 12650. Close. But then solidworks plots the bending stress about DIR1 as 21197 lbf/in2, despite the fact that there is no shear force to cause this, then gives a worst case value by adding those two. What?

 

Can anyone explain this? Thanks.

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