Thermo-Structural FEA of a CFRP Sleeve for an Electric Motor’s Permanent Magnet Rotor

This thesis aims to characterize, with the aid of finite element analysis, the behavior of a carbon fiber reinforced polymer sleeve mounted on the rotor of a permanent magnet electric motor for automotive applications. The goals of the simulations are to verify the resistance of the sleeve’s composite material under the most dangerous expected working conditions, to assess the capability of the sleeve to remain always in contact with the rotor and to verify that the sleeve does not break during the assembly phase of the system. In the first part of the thesis, an explanation of the system application is presented and an overview of fiber reinforced composite materials and their main properties is developed. The second part focuses on the FEM simulations performed on the system: different modeling approaches are evaluated, starting from planar models of sections of the rotor and arriving to more complex three-dimensional simulations. For each analysis, all the modeling choices are discussed and the related results presented. After the description of each 2D and 3D analysis, the results obtained through the different modeling approaches are compared, assessing the reliability of the simpler 2D models and their limitations. A chapter is dedicated to the press-fit applied for the connection of the sleeve with the rotor, a specific model is needed to verify the absence of damages during the assembly phase. The use of a carbon fiber reinforced polymer for the sleeve of a permanent magnet rotor turns out to be a feasible choice, as no failures are evidenced from the simulation results. Further studies should be considered on the technical and economic advantages of this choice over an interior permanent magnet motor.