Na Liu

Rectangular-hole-type crush initiators have attracted much attention due to their exceptional advantages in improving crashworthiness performance. Unfortunately, undesired deformation buckling modes, i.e. bifurcation buckling, can occur and challenge optimisation processes. This paper aims remedies to this limitation and proposes a machine learning based optimisation method that removes these undesired deformation modes to effectively evaluate the effect of initiators’ parameters in improving crush response. First, finite element models of square tubes with different numbers and positions of initiators were built and computed. Second, the complex proportional assessment (COPRAS) method was adopted to rank the crashworthiness characteristics. The results demonstrated that square tubes with two sets of four corner holes along the axial direction were the best choice. Finally, the optimisation method based on machine learning was employed to evaluate the influence of the initiator’s size on the crushing behaviours for minimizing the initial peak force (IPF), maximizing the energy absorption (EA), and crushing force efficiency (CFE). The results illustrated that the IPF of the optimised design Pareto front upper limit is about 21.94% lower, with 0.08% and 36.67% higher EA and CFE, respectively, than those of the best choice observed from COPRAS. This study highlights the ability of the proposed machine learning based optimisation method to improve crashworthiness performance.

Vehicle collisions may result in severe injuries to child passengers. These accidents are of concern to the automotive community; hence child restraint systems are now subjected to legislative requirements. New foldable child safety seats are a new technology that has the potential for space-saving whilst protecting children from injuries. For the first time, this paper proposes to evaluate the safety of such a foldable seat, considering multiple frontal impact directions. The research created a baseline 6-year-old HybridIII child sled test computer model, built from a correlated vehicle rear seat cabin interior environment model and including its crash pulse characteristics, in which various seat safety configurations were evaluated. A total of seven scenarios were investigated, considering no booster seat, a traditional booster seat, and a foldable booster seat, combined with different impact angles, including frontal impact (0°), near and far side impacts (15° and 30°). In each scenario, the child kinematics, seatbelt to neck interaction, head acceleration, HIC₁₅, and chest acceleration were extracted as metrics to determine the safety effectiveness of the foldable booster seat. The study concluded that the foldable booster seat reduced the risk of neck entrapment as well as better restrained the dummy in its seat. While the head acceleration, HIC_15, and chest acceleration may slightly increase, injury responses caused by the foldable booster seat are still well within safe margins. This study suggests that foldable booster seats are innovative and practical and have the potential, pending more research, to protect children in frontal collisions better.