Crashworthiness optimization for cutting energy-absorbing structures based on the multiobjective G-CBW method

The energy absorption structure of a train is an important part of passive safety protection during train collisions and is the last line of defense to protect both passengers and trains. In the design process of a train energy absorption structure, improved stability and greater energy absorption capacity is required. A cutting anti-climbing energy absorption structure offers good stability and energy absorption in a collision, but it can easily generate considerable heat in the energy absorption process. Therefore, it is important to conduct thermal–solid coupling simulations and crashworthiness optimization for cutting energy absorption structures. To improve the passive safety protection capability of high-speed trains, this paper experimentally and numerically explored the crashworthiness of a cutting-type energy-absorbing structure composed of an anti-creeper device, an energy-absorbing tube, cutting knives and knife-supporting tools. By adopting the Johnson–Cook material model, a finite element model was developed to study its energy absorption characteristics in a coupled heat–solid state. The effects of cutting depth (D), cutting knife front angle (A) and cutting width (W) on energy absorption (EA), cutting platform force (Fmean) and peak cutting force (PCF) were analyzed based on the validated simulation model. The results showed that EA, Fmean and PCF increase with increasing D and W, while EA, Fmean and PCF decrease with increasing A. The GRSM was employed as the optimization algorithm, and a gain matrix–cloud model optimal worst method (G-CBW) multiobjective decision algorithm was proposed to obtain the most satisfactory configurations from the Pareto front solution. The relative errors from the optimal and finite element results of EA, Fmean and PCF were 3.5%, 2.1% and 2.2%, respectively. All the crashworthiness indicators were improved considerably.