Degradation and fatigue of epoxy impregnated traction motors due to thermal and thermal induced mechanical stress - Part II : Thermal mechanical simulation of multiple wires due to evenly and unevenly distributed temperature

Part I of the study presents the importance and the analytical and numerical methods to perform a thermal- mechanical stress simulation with evenly distributed temperature for single wires. Part II of the study presents a method with thermal and mechanical conjugated simulations with unevenly distributed temperature for multiple wires and the results are compared to the structural simulation with evenly distributed temperature with the same geometry. Furthermore, based on the stress-fatigue curve of PAI insulation material, the stress-fatigue equation is fitted, which is adopted to estimate the lifetime due to thermal-mechanical stresses. This estimated life is compared to the estimated life based on Arrhenius Law and to the accelerated lifetime test