Material Interpolation in Multi-Material Topology Optimization for Magnetic Device Design

This paper investigates material interpolation schemes in multi-material topology optimization (MMTO) for magnetic device design. Different interpolations of material properties lead to a non-unique layout and differences in performance, thereby affecting the initial design dependence. However, there is a lack of research on material interpolation in MMTO for the magnetic design problem. In this research, two types of material interpolation schemes are compared: recursive multiphase (RM) and discrete material optimization (DMO). To compare only the effects of material interpolations, the non-convex feasible set of material constraints in RM interpolation schemes were transformed into the convex feasible set by a linear form. The performance profile was employed to obtain the global performance of each interpolation scheme. Examples of the C-core actuator and the permanent magnet actuator (PMA) were applied for performance comparison, and the performance profile indicated that the DMO interpolation scheme is robust to initial material distributions and different material constraints compared to the RM interpolation scheme.