Topology optimization of connectable microstructure using enlarged connective domain

• Published in: Structural and multidisciplinary optimization Vol. 66; no. 8; p. 174
• Main Authors: Matsui, Masayoshi, Hoshiba, Hiroya, Kamada, Hiroki, Ogura, Hiroki, Kato, Junji
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2023; Springer Nature B.V
• Subjects: Computational Mathematics and Numerical Analysis; Connectivity; Design parameters; Domains; Engineering; Engineering Design; Macrostructure; Manufacturability; Mechanical properties; Microstructure; Optimization; Research Paper; Theoretical and Applied Mechanics; Three dimensional printing; Topology optimization; Topology optimization; Connectable microstructure; Homogenization; Multi-scale analysis
• ISSN: 1615-147X; 1615-1488
• DOI: 10.1007/s00158-023-03613-w

Advances in 3D-printing technology have made it possible to manufacture structures containing periodic microstructures (lattice structures) and obtain superior mechanical performance that cannot be provided with uniform solids. To achieve the best performance, microstructures with different properties should be optimally designed and arranged in the right places within the macrostructure. However, in most of the basic approaches with homogenization theory, each microstructure is analyzed and optimized separately under periodic boundaries, so connectivity with adjacent microstructures is not considered (or guaranteed). Consequently, unrealistic discontinuous structures are often obtained, resulting in poor mechanical performance and manufacturability. To address this problem, we propose a method to introduce an "enlarged connective domain" around the boundary when dividing the macrostructure into multiple domains with different microstructures in advance. The microstructure of the enlarged connective domain is formed by combining the unit cells of adjacent microstructures, which allows micro-scale connectivity to be reflected in the macrostructure. Therefore, this method improves the mechanical connectivity between microstructures through the original optimization process of maximizing the performance of the entire macrostructure. This paper demonstrates that the proposed method improves connectivity and mechanical performance by performing optimization analyses for two- and three-dimensional problems. In addition, we focus on the width (volume ratio) of the connective domain as a design parameter that specifies the degree to which connectivity is considered and discuss how to set the parameter appropriately.