Structural Multi-objective Topology Optimization in the Design and Additive Manufacturing of Spatial Structure Joints

Topology optimization and additive manufacturing are of particular importance in solving the problems of stress concentration, excessive steel consumption, and excessive displacement in spatial structure joints. In this work, we investigate the best topological form for such joints under multi-objective topology optimization (MTO). We conducted a single-objective topology optimization (STO) analysis on the joint first, in the optimization process, the influences of penalty parameters, minimum member size, symmetry constraints, and the checkerboard phenomenon were comprehensively considered. Through comparative analysis, the optimal values for various load conditions were obtained, according to the optimal value obtained by STO, the MTO calculation of joint is carried out by using the compromise programming method. Then, the Nurbs modeling method is used to redesign the preliminarily optimized result, and the smooth joint is obtained. The mechanical performance of single-condition and multi-condition, MTO and STO, MTO joint and hollow sphere joint are compared with the same steel consumption. The results show that the mechanical performance of the joint obtained by MTO is more uniform than those obtained by STO, and the mechanical performance of the joint obtained by MTO is better than those of hollow sphere joint under the same steel consumption. Finally, the optimized joints were fabricated via additive manufacturing, which produced joints with novel shapes, smooth surfaces, and light weights.