Energy distribution analysis and multi-objective optimization of a gradual energy-absorbing structure for subway vehicles

This paper addresses the energy absorption response and crashworthiness optimization of a gradual energy-absorbing structure which is composed of nested thin-walled square tubes under axial quasi-static loading. The experimental and numerical results indicated that the deformation model of the structure is regularly and stable and the collapse process is clearly divided into two stages. The energy distribution of two stages are 43.83% and 56.17%, respectively. To explore the effects of thickness parameters of each part of the structure on energy absorption characteristics such as the specific energy absorption (SEA) and the dimensionless parameter φ1 which indicates that energy distribution of the collapse process, the response surface (RS) models for the design of experiments (DOE) were employed along with the finite element model (FEM) which is experimentally calibrated. In addition, based on the developed RS models, multi-objective optimization design (MOD) was carried out by using Multi-Objective Genetic Algorithm (MOGA). It was found that the uniformity of energy distribution of two stages and the SEA cannot reach the optimal value at the same time. Lastly, the optimization results can present a good design matrix to get energy-absorbing structures with excellent performance regarding the crash-worthiness of subway vehicles.