An evolutionary design approach to shell-infill structures

Shell-infill structures with internal porous architecture are increasingly used in additive manufacturing because of their advantages such as material saving, printing efficiency, and thermal stress release. The study is built upon the bi-directional evolutionary structural optimization (BESO) method. An evolutionary design approach to shell-infill structures using flexible control of the infill architecture is proposed in this study. Specifically, the general structural configuration with a coating shell is first designed by assuming that the infill consists of a weak material. The delicate fine infill architecture is subsequently designed by extending BESO to consider the maximum length scale constraints of the infill architecture. Shell-infill designs of variant functionally graded infill architectures are additively manufactured using stereolithography and their mechanical performance are tested. Numerical and experimental results indicate that the proposed method is more effective in providing shell-infill designs with optimal stiffness and robust performance compared to conventional designs with uniform lattice infill.