Crashworthiness optimisation of the front-end structure of the lead car of a high-speed train

To improve the crashworthiness of vehicles, the crashworthiness of the vehicle structure itself has to be optimised. Through the collision analysis of a certain high-speed train, this research found that the front-end structure is most important in the crashworthiness optimisation design of the vehicle; the constitutive material models required for this numerical simulation of an entire vehicle were obtained by performing loading tests at different strain rates; according to the highly non-linear characteristics of the ensuing structural deformation under impact loading, this research used specific energy absorption (SEA) as an objective function to construct a multi-parameter optimisation model of the front-end structure of the vehicle . Based on this, the optimisation analysis was conducted. In the optimisation, the optimal SEA value (3.6988 kJ/kg) of the structure is obtained by 130-step iteration using a modified method of feasible directions (MMFD)—a gradient optimisation method; the optimal value obtained after 101 iterations by applying a direct search method—Hooke-Jeeves (HJ) algorithm is 3.6454 kJ/kg; and the optimal value acquired after 192 iterations of a global optimisation method—adaptive simulated annealing (ASA)—is 3.6132 kJ/kg. Moreover, the optimum results were validated by collision analysis of the optimal structure using a MMFD model. The variation analysis of the structural SEA with each variable show that the optimisation model is able to extend the range of each design variable.