Evolutionary Topology Optimization Design Of Shell-infill Structures

Shell-infill structures with internal porous architecture are increasingly used in additive manufacturing because of merits such as material saving,printing efficiency,and thermal stress release.For its high design freedom and efficiency,topology optimization has been widely researched and successfully applied in many industrial fields in the last decades.Among all methods,the bi-directional evolutionary structural optimization method(BESO)method is favored by many researchers and engineers for its simplicity and high efficiency.This work proposes an evolutionary design approach based on BESO to shell-infill structures with flexible control of the infill architecture.The main content is summarized as follows:Firstly,an evolutionary design approach to shell-infill structures is developed,which consists of two sequential design steps: 1)general design of the coated structural configuration and 2)detailed design of the infill architeche.Specifically,it is assumed in the first step that the interior of the structure is filled with homogeneous material with weak performance,and topology optimization design is performed to achieve multi-material(empty/weak infill/strong shell)coated structural configuration.Secondly,refeined infill structure is design replacing the weak homogeneous material assumed in the previous step,and the maximum structural length scale is constrained to achieve flexible control of the infill architecture.Secondly,the method is performed for two typical benchmark design problems to verify the effectiveness and reliability.Numerical designs show that shell-infill structural designs with improved stiffness can be effectively achieved by constraining the maximum length scales.Shell-infill designs with improved stiffness were obtained by the proposed method considering various lattice configurations as the initial infill.It has been shown that the intial infill lattice configuraiton has a significant impact on the final design.Finally,the validity of the design method is further verified by mechanical testing.The shellinfill MBB beam designs were taken as the sketch for the construction of 3D models.Attachmenet substructures were added to 3D models to simulate the partical fit installation of the specimens and the three-point bending fixture.Photosensitive resin SPR6000 B was used for 3D printing of specimens and the three-point bending test was performed for the specimens.Experimental results indicate that the proposed method is more effective in providing shellinfill designs with optimal stiffness and robust performance compared to conventional designs with uniform lattice infill.