Multi-objective topology optimization for solid-porous infill designs in regions-divided structures using multi-patch isogeometric analysis

Recently, how to simultaneously consider porous infills and solid topology designs in different subregions with different performance requirements in whole structures has been a critical design problem, which has accepted more and more attentions among many researchers. In the current work, the main intention is to develop a Multi-Patch Isogeometric Topology Optimization (MP-ITO) method for multi-objective designs of regions-divided structures, where the solid topology designs, porous infill designs and solid-porous infill designs are all addressed in the optimization. In the MP-ITO method, the multi-patch NURBS-based IGA is applied to couple all divided subregions in the whole domain to solve the unknown structural responses, and each subregion is modelled by one NURBS patch. An efficient topology description model is developed for regions-divided structures using the Density Distribution Functions (DDFs), in which a local smoothing mechanism keeps the connectivity and smoothness of structural topology. The two-resolution discretization meshes are used in topology description model and numerical analysis. Three multi-objective optimization formulations for solid topologies, porous infills and solid-porous infill designs of regions-divided structures are developed using the MP-ITO method, where the stress-minimization and compliance-minimization are respectively addressed in different subregions. Finally, several numerical design examples are discussed to present the effectiveness and indispensability of the multi-objective design formulations, and results reveal that the optimized solid-porous infill designs can be better for engineering applications.