Multi-objective Structural Optimization Design of Ti6Al4V Lattice Structure Formed by SLM

Abstract

Taking advantages of simple type of topology, high manufacturing reliability and single form of compression failure, body-centered cubic (BCC) lattice structure has raised a widespread concern in recent years. However, it has the shortcoming of relatively poor bearing capacity. In order to explore a specific kind of lattice structure with light-weight and good mechanical properties, a body-centered tetragonal (BCT) lattice structure is proposed by removing the constraint of isotropy size in BCC lattice structure. A multi-objective optimization model for the configurational size of the BCT lattice structure is developed by taking the size of BCT cell configuration as the design variables, the size of lattice material and manufacturing process as the constraints, and the relative density, the initial stiffness and the strength of plastic collapse as the multi-objective evaluation functions. Based on the optimization model, the optimal configuration dimension of BCT lattice cell is obtained by using the ideal point method. The performance advantages of the optimized BCT structure are proved by comparing with the BCC reference structure through simulation analysis. Finally, the experimental samples of the optimized BCT structure and BCC reference structure are fabricated by selective laser melting (SLM) using the material of Ti6Al4V. The quasi-static uniaxial compression experiment is conducted and the theoretical analysis results are verified. The theoretical and experimental results have general applicability to the design and research of the light-weight lattice structure materials.