Geometry optimization on the cross section of adhesively bonded thin-walled composite beam subjected to axial crushing load

Abstract

Adhesive bonding is widely used in structural connection of composite components due to its capacity to effectively avoid inducing stress concentration and damage in composite components. This work applies a design optimization methodology on the geometry of cross section and ply thickness in adhesively bonded CFRP (carbon fiber-reinforced plastic), hat-shaped, thin-walled beam in automobiles to achieve car body lightweight design. A multi-objective and multi-constraint design optimization problem was formulated to find the optimum key cross-section size and ply thickness of the hat thin-walled beam. The minimum total material cost and maximum energy absorption (EA) during the axial crushing test of the CFRP beam were selected as the optimization objectives. The non-dominated sorting genetic algorithm II (NSGA-II) was introduced to search for global optimum solution, and radial basis function (RBF) approximations for the objective functions were applied to reduce the computational cost. It was revealed that EA increased by 8.28%, while the total weight and cost decreased by 3.14% and 3.23%, respectively, and can thus provide a guidance in vehicle composite component design.