Crashworthiness performance of gradient energy-absorbing structure for subway vehicles under quasi-static loading

To improve the uncertainty of the deformation sequence of the energy-absorbing structures at the end of the subway vehicles during crushing, this paper adopts the gradient design idea of honeycomb structure size, collapse initiator groove and diaphragm. To this end, this paper proposes a honeycomb-filled gradient energy-absorbing structure (HGES) as an energy absorber. The crashworthiness of HGES under axial crushing was investigated by means of finite element (FE) simulations and quasi-static loading tests. After performing parametric analyses on HGES, it was discovered that the wall thickness and the platform intensity of honeycomb had an evident impact, whereas the diaphragm thickness had a relatively little impact on the crashworthiness of HGES. The HGES is then given a multi-objective optimization to further enhance its crashworthiness. The wall thickness, the platform intensity of honeycomb and diaphragm thickness were utilized as the design parameters, while minimal peak crushing force (PCF) and maximal specific energy absorption (SEA) were set as optimization objectives. Finally, a methodology integrating entropy and the order preference by similarity to an ideal solution (TOPSIS) is employed to find the optimal HGES configuration. The SEA and PCF of optimized HGES are enhanced by 19.81 and 25.28%, respectively, when compared to the baseline.