Crashworthiness of Energy Absorbing Structures Under Combined Shear-Compression Loading: Effects of Materials and Geometries

Abstract

In this paper, a study on the design of energy absorbing structures under combined shear-compression loading is conducted to effectively utilize the energy absorption principles of the material. Concave and convex designs are applied to energy absorbing structures made of metallic and braided composite materials. The energy absorption principles vary depending on the characteristics of each material. For metal, a design maximizing energy absorption through plastic deformation is necessary. Concave and convex designs induce initial crushing due to stress concentration under loads, reducing the maximum load. Subsequently, the load is distributed throughout the entire structure, improving load-bearing performance and enhancing energy absorption performance. Braided composites demonstrate superior characteristics in terms of specific stiffness, specific strength, and specific energy absorption when compared to metals. They absorb energy through damage accumulation in the laminate. Therefore, to optimize the performance, inducing a progressive failure mode becomes necessary. Unlike metals, braided composites can achieve effective energy absorption performance without altering the geometric shape. Energy absorbing structures are manufactured, and drop impact tests are carried out to assess their performance. In conclusion, it is observed that the geometric shapes effective in enhancing crashworthiness performance vary according to the energy absorption principles of each material. Also, the energy absorption per unit volume is found to be superior for metal energy absorbing structures, whereas the energy absorption per unit mass is better for composite energy absorbing structures. Therefore, depending on the application, both metals and composites can be effectively utilized as materials for energy absorbing structures.