I'm curious if anyone can provide any input on how Solidworks calculates the torsional constant and max shear stress distances for beam cross-sections. I've run numerous beam torsion tests on thin-walled open and closed sections, comparing them to hand calculations and solid models. For most of the open sections, I've found relatively decent agreement between the software's torsional constant calculation and the hand calculation, where J is found for the profiles by either unfolding or breaking them into individual rectangles. However, in these cases, the max shear stress is based on the thinnest section thickness, and the software's "distance for max shear stress" is generally off by a factor of 5-10x, resulting in huge simulated torsional shear stresses. Can anyone provide any insight?

Please see solution S-018800 in the SOLIDWORKS Knowledge Base (KB) for detailed information about this. If you are not already familiar with the SOLIDWORKS Knowledge Base (KB), please see About Subscription Services & the KB (public)

In summary, SOLIDWORKS Simulation uses a general and conservative method to calculate the "Constant for maximum shear stress calculation (CTOR)" value of beam element cross sections. By comparison, text books typically devise special formulas for each cross section that they study. Therefore, the τmax value given by SOLIDWORKS Simulation will always be greater than either the prediction made by the textbooks (Roark's Formulas for Stress and Strain, for instance) or values obtained from SOLIDWORKS Simulation for the same analysis using solid elements.