Design and Mechanical Properties of Star-Shaped Structure with Double Stress Plateaus

To achieve the tunable plateau stress and energy absorption in porous grid structures, a design method for star-shaped structures with double stress plateaus was proposed. Three kinds of star-shaped structures with double stress plateaus were designed and fabricated. The mechanical behavior and energy absorption properties under in-plane compressive load were investigated through experimental tests, theoretical analysis and numerical simulations. It was shown that the star-shaped structures with double stress plateaus exhibit two distinct plateau steps in the load-displacement curves. The geometric parameters of the structure and the number of ribs have a significant effect on the structural deformation stability and the plateau stress. The theoretical predictions, experimental results and numerical simulations were in good agreement with each other. The plateau stress and energy absorption capacity of star-shaped structures can be effectively controlled by tuning the corresponding design parameters. To further improve the energy absorption capacity of the star-shaped structure with double stress plateaus, a multi-objective optimization method was performed using the mass and specific absorption energy of the structure as design variables. The radial basis coupling polynomial function proxy model and genetic algorithm (NSGA-Ⅱ) were used to maximize the specific energy absorption and minimize the mass of the structure. Compared to the original structure, the optimized structure has a 6.0% reduction in mass and a 21.5% increase in specific energy absorption.