A novel method for structural strength modeling of lamination stacks of electric motors using contact in FEA

The automotive industry is transforming from traditional internal combustion drive systems to alternative ones, mostly based on electric motors. Fueled by strict requirements and high competition on the market, simulation has become an essential part of the development process. The precise structural strength simulation of rotors is extremely difficult, as a consequence of the nonlinear mechanical behavior of the lamination stack. Due to computational limits, this part has traditionally been simulated as a solid structure with orthotropic linear material models. These models were not capable of accurately simulating the axial nonlinear stiffness, the separation / slip of individual sheets or their plastic deformations. The method presented in this article does not have these limitations. By using a stacked shell approach, simulating all of the sheets separately using a contact model developed especially for this purpose, the method can be used to model real rotors using a fair amount of computational resources. The new method contributes significantly to the precision of virtual tests of rotors used in electric drives. • A new stacked shell based method has been introduced for structural strength simulation of electric drives. • Normal and shear nonlinear stiffness behavior of lamination stacks have been successfully modeled using contact. • The new approach can simulate axial nonlinear stiffness, sheet separation and plasticity for complete rotor assemblies. • The method is fast and stable enough to be used in industrial applications. • A virtual burst experiment of a rotor has been performed and validated using physical tests.