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Part incorrectly showing no stress due to thermal expansion

Question asked by Robert Drake on Jul 30, 2013
Latest reply on Jul 30, 2013 by Robert Drake

I am simulating the stress and thermal expansion of a lens due to a very hot and bright light source.  When I try to use the thermal simulation results in the stress and displacement simulation it shows everything as the same stress, no displacement. It does not give an error, but the results are clearly wrong.  I have the bulb and lens in an assembly.  I model the bulb as a radiant source and the lens has convective cooling on its outside.  The temperature results plot is pretty close to my experimental confirmation.  I think I have a pretty good thermal model and I want to see how much this makes the lens expand and what stress that puts on the lens.  I tell the stress simulation to use the thermal results and it simulates with no errors, but as stated above, uniform stress...somethings wrong.  I can apply temperatures to the lens model and it will deform and stress appropriately when modelling the part on its own.  I don't care about the bulb stress, so I tried suppressing the bulb in the stress simulation after I did the thermal simulation with them both, but then it errors and says the number of parts does not equal the number in the thermal analysis.  I really want to use the results from the assembly thermal simulation with the lens parts stress simulation, but cannot figure out how to.  Whether I get bulb stress results or not I don't care, I just want the lens.  I also tried to find a way to copy thermal results from just one part in an assembly simulation to just the part for simulation, but could not find one.  Any suggestions to achieve my goal of using the thermal assembly results to model stress in the lens part?  Thank you.