I am doing a thermo-mechanical coupling simulation for the rotor carrier of an axial flux machine which has the permanent magnets glued to it. I applied my magnetic forces on the magnets and a centrifugal force. I added a thermal load of 90C to the model but suddenly stress in my titanium rotor jumped from 175MPa to 860MPa which didn’t seem reasonable. Upon studying the results, I noticed that high thermal stresses were formed in the constraint location. I studied the mechanism once again and thought about it. Upon thermal loading the rotor expands radially and henceforth I released the radial cylindrical coordinates in the constraints. Now the problem is that Nastran wouldn’t run the model because it throws the “max pivot ratio” error which means my model is under constrained. I added the MAXRATIO card but still failed. I want the model to run with this specific constraint in order to reduce my thermal stress. Any suggestions?
