Multi-objective optimisation of functionally graded honeycomb filled crash boxes under oblique impact loading

Tubular forms of crash elements such as crash boxes are widely applied in transportation industries, especially in automobile industry. A crash box is an element used in the frontal crash zones, generally inserted between chassis and bumper to reduce the amount of crash energy that is transmitted to the rest of the front safety zones. In this paper, first, square section crash boxes filled with functionally graded honeycomb (FGH) subjected to oblique impact loading is presented with the objective to improve crashworthiness. Then, some optimisation tools such as the weighted average method, the geometrical average method, and multi-design objective optimisation technique are utilised to optimise the crash box structures. The optimisation results reveal that the crashworthiness of the FGH filled box structures exposed to the oblique impact loading is improved, and also proves its superiority with respect to the uniform honeycomb filled box structures. Finally, the metallic honeycomb density exponent gradient is properly determined.