Crashworthiness Research And Design Of Thin-walled Structures With Variable Cross-section

Thin-walled structures have been widely used as energy absorbers in automobile and aviation, due to their significant advantages on crashworthiness and light weight, and the research on thin-walled structures has become more and more attractive. However, relatively few studies have been reported about how the effect of cross-section of thin-walled structures varying on crashworthiness. Herein, a new thin-walled structures with variable cross-section along the longitudinal direction is introduced and its crashworthiness is comprehensively discussed as follows:The diameter of thin-walled tapered tubes is designed in a functionally graded manner. The functionally graded tapered tubes(FGTT) are impacted under axial load by finite element modeling and the accuracy of the FE model is validated by experiment data. To study the crashworthiness, the specific energy absorption and initial peak crushing force are discussed and the results show that FGTT has great advantages on energy absorption over the traditionally straight/tapered circular. Then, the parametric study is carried out to investigate the effects of configuration. Finally, the optimization design is used to optimize the FGTT tubes and the optimal FGTT tubes have great potential for energy absorber.Considering energy absorbers in automobile usually experience an oblique load when an actual vehicle accident occurs, the FGTT tubes are modeled under multi load. By investigating the crashworthiness of FGTT under oblique load, it is found FGTTs have better energy absorption capacity under small impact angles with a gradient exponent of n>1. Then, the analysis of different crushing distance, graded exponent n and impact velocity are also conducted.Front rails(S-shaped beams), as the most important component in automobile, need high energy absorption capacity. Herein, S-shaped beam is designed with cross-section variable along neutral axis. By studying the variation form of cross-section and geometrical parameters, the S beams with diameter varying linearly from top to end have superior crashworthiness. The investigation mentioned above can provide significant reference to automobile energy absorbing structures design.