Development of a model to describe the stiffness of an electric motor lamination stack

A light-weight design is becoming increasingly important for electric motors. As a consequence, adequate knowledge of the mechanical behavior of the lamination stack is of prime importance, since the lamination stack has a significant influence onto the behavior of the complete motor due to the significant contact characteristics between the single sheets. Quasi-static tests are performed to identify this stiffness behavior. A load representing the packaging process is first applied onto the stack. A cyclic load is then superposed to simulate the forces during the motor lifetime. With these quasi-static tests a progressive stiffness behavior with elastic and plastic effects is identified. This non-linearity can be attributed to the sheet´s roughness and surface waviness. Based on the identified contact stiffness, an improved simulation of the quasi-static behavior of an electrical motor is possible.