# Design of the multi-material structure using an MMC-SIMP sequential topology optimization method

## TL;DR

This paper introduces a new method for designing multi-material structures by combining two optimization techniques in sequence.

## Contribution

The novelty is a sequential method combining MMC and SIMP for multi-material structure optimization.

## Key findings

- The method achieves explicit external structural topology and flexible internal material layouts.
- The proposed approach is verified through numerical examples and is shown to be easy to implement.
- Key MATLAB codes are provided to support the method's practical application.

## Abstract

The present paper introduces a sequential topology optimization method for multi-material structure design. In the proposed method, the moving morphable component (MMC) method and the solid isotropic material with penalization (SIMP) method are performed in sequence to achieve multi-material structure optimization. First, the structural topology is obtained using the MMC method, and then the material layout of the determined structural topology is optimized using the SIMP method. The connection between MMC method and SIMP method is established through components mapping elements, where changes in the material layout within these elements do not affect the external structural topology. The proposed method effectively combines the advantages of two optimization methods, enabling the achievement of an explicit external structural topology and greater freedom in internal multi-material layouts, while remaining easy to implement. The key MATLAB codes for the proposed method are provided in the paper. Finally, the feasibility of the proposed method is verified through some numerical examples.