RESIDUAL STRESS PREDICTION OF ADDITIVE MANUFACTURED ELECTRIC MOTOR CORES USING FINITE ELEMENT ANALYSIS

This thesis work aims to investigate the possibility to use selective laser melting (SLM) to produce electric cores for a traction electric motor. SLM is a powder bed based additive manufacturing (AM) technique that guar- antees relative structural density of the build part > 99%. This is one of reasons why SLM is among the most interesting processes to research on in the field of electric motors produced by AM. However, this technique is also chacaterized by high residual stress because of the high and repeated temperature gradients during the construction making it similar to a laser welding process. The prediction of residual stress is conducted in this study by performing a thermal-to-structural Finite Element Analysis (FEA) on a commercial software for additive processes ( ANSYS Workbench) on one material available in its library (316 stainless steel). These results are vali- dated by performing a convergence analysis, and similar results are expected in experimental samples based on open literature. However, validation by X-ray diffraction (XRD) is recommended for future work. At first, the pa- rameters in the simulation are set to be consistent with previous research aiming at optimizing the process inputs to get a full dense part. The pro- cess parameters are subsequently changed to investigate their in uence on the residual stress and the possibility to find a mitigation strategy based on the inputs of the process. It is shown that the residual stress values are independent of those parameters, at least when using values that still guar- antee a part with low void formation and internal cracks. Then, the heat treatments are suggested as mitigation strategy to be investigated experi- mentally in future studies. Based on the results of the numerical simulation, a topological optimazation has been performed on the stator to fully exploit the potential of AM processes in terms of freedom of design.