Multi-Objective Optimisation of Composite Absorber Shape Under Crashworthiness Requirements

Moving from a validated finite element model of composite cylindrical absorbers, this work aims to optimise the shape of conical absorbers with elliptical cross-sections considering simultaneously different impact conditions. Since the use of non-linear finite element analyses to directly evaluate objectives and constraints during the optimisations would be unaffordable from a computational standpoint, a global approximation strategy is used. The crash capabilities of the absorbers are approximated with a system of Radial Basis Functions built by means of a minimum number of finite element analyses. The response surfaces are coupled with Genetic Algorithms to perform both constrained single- and multi-objective optimisations. The results prove that moderate eccentricity and conicity lead to high efficiency structures characterised by stable crush fronts and good absorption capabilities with also associated mass reduction up to the 7% considering vertical impacts and at least of the 20% considering 20 impacts with respect to ideal cylinders.