An assemblable interlocking joint generation method for multi-material topology optimization using interfacial partial stress constraints and dimensional constraints

Multi-material topology optimization has become a promising method in structural design due to its excellent structural performance. However, existing research assumes that the multi-material structures are joined by welding, adhesive, or other methods that do not support reassembly and disassembly and are unsuitable for manufacturing, limiting the practical application of topology optimization. An interlocking joint is a type of connection between two parts where the shapes of the parts are designed to fit together precisely, the multi-material structure joined by interlocking joints can be easily reassembled repeatedly. To solve the joint problem of multi-material structure, this study proposes an assemblable interlocking joint generation method for multi-material topology optimization, the connection between material components is achieved through compression at the joint areas. To generate the interlocking joints, a novel interfacial partial stress constraint is proposed by converting a part of the interface bearing tensile stress into the interface bearing compressive stress. A novel filtering process is used to control the shape of the interlocking joints and the filtered tensile stresses are integrated by a P-norm function. To constrain the distribution area of material components and ensure structural manufacturability, dimensional constraints are applied. The sensitivity is based on the topological derivative and adjoint variable method. The proposed method was applied to several numerical examples including one manufactured prototype to demonstrate its effectiveness and contribution to the practical application of topology optimization.