Multi-objective Optimization for Bus Rollover Crashworthiness

Finite element model of a bus rollover was established,whose simulation results show that the initial design could not pass the ECE Regulation No.66.Therefore,the bus structure needs to be optimized.To overcome the difficulties of high nonlinearity of crashworthiness analysis in optimization,the surrogate models of rollover responses were established by combing with uniform design of experiments,response surface method and stepwise regression techniques.A multi-objective optimization was implemented by NSGA-II,in which the objectives are to minimize the weight of the bus body and to maximize the absorbed energy of the bus frame,and the constraints are to meet the regulation of rollover.The optimal designs were verified by finite element simulation.The results show that optimal designs not only make the bus to meet the requirements of ECE Regulations No.66,but also reduce the mass of the bus body,while increasing the absorbed energy of the body structure,which effectively improve the rollover safety.