Theoretical prediction and crashworthiness optimization of top-hat thin-walled structures under transverse loading

In this study, a theoretical model is developed to reveal the bending collapse of top-hat thin-walled structures by dividing a top-hat thin-walled structure into a top-hat element and flat-plate element. A theoretical formula is also developed to describe the bending deformation and energy-absorption of the structures. The theoretical model is capable of predicting the bending collapse and energy-absorption of top-hat thin-walled structures with different thickness and material specification. The accuracy and generality of the theoretical prediction model is validated by performing three-point bending tests and finite element simulations. Then, both theoretical prediction formulas and finite element analysis (FEA) based surrogate models are employed to perform the crashworthiness optimization of top-hat thin-walled structures. The results show that (i) the theoretical prediction model is capable of producing results that can be directly used to optimize the thicknesses, cross-sectional geometry, and material specifications for top-hat thin-walled structures, which will increase the efficiency and shorten the cycle time of crashworthiness design optimization for this type of structure; and (ii) steel-aluminum hybrid top-hat thin-walled structure has a larger energy-absorption capacity than high-strength steel without exceeding the initial weight, whereas a lightweight design is more feasible with an aluminum alloy than with high-strength steel without sacrificing the energy absorption of the baseline design.