Dynamic impact behaviour and structural optimisation of crashworthiness of aluminium alloy thin-walled circular tubes

In this paper, a new type of thin-walled energy absorption circular tube was proposed with rectangular holes by combining numerical simulation and optimisation algorithm to improve the crashworthiness performance of the thin-walled tube. The quasi-static compression and dynamic impact mechanical experiments of 7150-T6 aluminium alloy were carried out by using universal testing machine and split Hopkinson pressure bar (SHPB). Combining with Johnson-Cook (J-C) model parameters identified by computational inverse method, the finite element model (FEM) for SHPB was established to estimate the force–displacement curve and the crashworthiness of circular tubes, and the reliability of this model was verified by comparison with experiments. Based on this model, the crashworthiness and energy absorption behaviours of circular tubes are investigated, and the results show that holes can effectively mitigate fluctuation, reduce the impact load and improve the crashworthiness. By comparing with the results of the simulation, it was found that the circular tube with rectangular holes is more conducive to reduce the peak load and improve the crashworthiness of the circular tube. Finally, the optimal structure of circular tubes with rectangular holes are studied by multi-objective optimisation algorithm to enhance energy absorption capacity. Hence, the optimisation method based on response surface and genetic algorithm used in this paper is an effective way for crashworthiness design and optimisation.