Topology Optimization Design and Mechanical Properties of 3D-Printed Solid-Lattice Hybrid Structures with Variable-Density or Iso-Density

In this study, the topology-optimized solid-lattice hybrid structures with variable-density or iso-density are proposed to achieve the structural lightweight and performance requirements. Based on solid isotropic material with penalty topology optimization method, novel optimized structures are designed, including pure solid structure, pure lattice structure, and solid-lattice hybrid structure with iso-density or variable-density. All experimental samples with few 3D-printing defects are fabricated by selective laser sintering additive manufacturing method. Both three-point bending test and finite element simulation are conducted to evaluate the mechanical behaviors, including force-displacement curves and failure modes. Results show that hybrid structure with variable-density lattice has the highest peak force, while the pure lattice fails at the largest displacement which presents high energy absorption. The stress concentrations at the topology-optimized solid region are significantly alleviated by the support of the distributed lattice. It is illustrated that the reasonable lattice distribution around the topology-optimized solid region to increase the structural efficiency is mainly responsible for the obvious improvements. Furthermore, the solid-lattice hybridization-based topology optimization method is applied to the automotive crash beams, and simulations are performed to verify the effectiveness of method. This method provides valuable guidance for lightweight design of high-performance complex structures.