I have a flexible shaft in my model by importing an MNF file. I have found the deflection of the shaft (simply supported) is dependent to the number of modes. Only a radial load is applied to the shaft center and I need to confirm the shaft center displacement with classical formulations. I already have 14 modes and I doubled it to 28 and the results changed. Why does this dependency happen? The 60mm diameter shaft spins at a low speed 100 rpm
