Multiscale topology optimization of electropermanent magnet composites in magnetic actuators

Abstract

Electropermanent magnet (EPM) composites are engineered structures that integrate permanent magnets (PMs) and iron at the microscale. This work aims to demonstrate that a graded EPM microstructure, designed through multiscale topology optimization, enhances the magnetic force of actuators beyond that of traditional single-scale designs. Specifically, a homogenization-based multiscale topology optimization approach is employed in this work, consisting of three steps: (1) constructing a surrogate model of effective material properties, (2) determining the optimal distribution of macroscopic and microstructure design variables, and (3) reconstructing the optimized EPM microstructure at the macroscale. The effectiveness of this approach is evaluated through three numerical examples. The first example provides the design results at various iron-to-PM volume ratios. The second example quantitatively compares the magnetic forces of multiscale and single-scale designs, demonstrating the superiority of the multiscale approach. The third example investigates the effect of EPM unit cell rotation and PM magnetization direction change. This study confirms the potential of multiscale topology optimization in addressing magnetic field problems for electromechanical systems.