An experimental and numerical study on the crush responses and energy absorption characteristics of single- and bi-layer cups under low-velocity impact

Observations on the crush responses and the energy absorption characteristics of single-and bi-layer deep-drawn cups subjected to experimental axial impact loading are presented in this manuscript. Bi-layer plates composed of aluminum and stainless steel alloys were fabricated by joining with adhesive and formed by a deep drawing process to produce the final cup shape. Impact testing was performed using a custom-built drop-tower system with a mass of 45.45 kg and impact velocities ranging from 2.8 m/s to 4.5 m/s. Various material and geometric parameters for the bi-and single-layer cups were considered in the study. Numerical simulations were conducted to investigate the deformation mechanisms and crushing behavior of the combined shells. Furthermore, based on the polynomial response surface method and using non-domain sorting genetic algorithm II, some multi-objective optimizations were performed on specific energy absorption, stroke efficiency, specific total efficiency, and initial peak load. Experimental and numerical results illustrated that the deformation of the bi-layer cups was different from the single-layer cups, especially in the head zone. Moreover, the specific total efficiency for specimens having a diameter of 55 mm and 65 mm were approximately 35% and 55% less than cups with a diameter of 45mm, respectively. It was found that the layer order of the bi-layer cup influences the energy absorption capacities of the specimen. Specifically, cups with steel as the outer layer experienced crush force efficiency and total efficiency of 6% and 5% higher than those with an aluminum outer layer, respectively.