ANALYSIS AND DESIGN OF IMPACT RESISTANCE PERFORMANCE FOR THREE LATTICE STRUCTURES UNDER CONSISTENT WEIGHT CONSTRAINT

Lattice structure is a periodic porous structure with the multifunctional characteristics such as energy absorption and load-bearing. By selecting and designing its constituent unite cells, it can meet the impact resistance requirements of key components in the aerospace and mechanical structures. In this work, we establishes a lattice structure model composed of three types of unite cells: hexagonal, star shaped, and spline. Under the condition of satisfying precise same weight constraints, the impact staged energy absorption characterization is taken as the optimization objective. Genetic optimization algorithm is used to design the shape and size of lattice structure cells, and the impact resistance performance of the optimized configuration is evaluated. In the optimization design model, the energy absorption characteristics of the impact process are characterized in three stages based on the stress-strain response process: linear elastic stage, stress plateau stage, and densification stage. By analyzing and comparing the optimized configurations of three types of unite cells, it is shown that under the same weight constraint, the lattice structure composed of hexagonal lattice with zero Poisson's ratio cells and spline lattice cells with smaller curvature has higher specific energy absorption in the first two stages, making it suitable for lightweight load-bearing energy absorbing structures. The lattice structure composed of concave cells in the star lattice and cells with larger curvature in the spline lattice has higher specific energy absorption and lower initial peak stress in the third stage, and the lattice structure composed of star lattice cells has lower equivalent stress throughout the impact process, making it more suitable for impact protection structure design. Finally, a hexagonal lattice structure was selected, and experimental samples were processed using additive manufacturing. The effectiveness of the design and analysis method for the impact resistance performance of the lattice structure was verified through Hopkinson bar impact testing.