Design of heterogeneous mesoscale structure for high mechanical properties based on force-flow: 2D geometries

Abstract

Mesoscale structure (MS) design of parts unlocked by additive manufacturing has a significant impact on their mechanical and physical properties. Conventional homogeneous MS designed based on unit cells is not a globally optimal structure due to the incompatible with the variable stress field under the applied load. In contrast, naturally evolved heterogeneous MS such as bones and bamboos are perfectly adaptive to their applied loads and exhibit excellent structural efficiency. Therefore, a heterogeneous MS design method of 2D geometry based on force-flow for high mechanical properties is proposed. The generation methods of two characterization forms of force-flow, principal stress lines and load paths, force-flow guided heterogeneous MS generation method, and MS volume fraction control method are detailed. Force-flow is generated using interpolation method based on the stress information extracted from finite element analysis (FEA) results. Then, force-flow is used as a guide to generate heterogeneous MS highly coordinated with the stress field. Customization of heterogeneous MS volume fraction is achieved by regulating the sparsity of force-flow lines based on the number of seed points in the design domain. Finite element simulations and mechanical tests of different specimens demonstrate that force-flow based heterogeneous MS has higher strength and stiffness compared to homogeneous honeycomb MS and grid MS.