Optimisation design of reinforced S-shaped frame structure under axial dynamic loading

For S-shaped frame structures (SFSs) in vehicle body, the multi-diagonal reinforced frame (MRF) might bring higher energy absorption than the single-diagonal reinforced frame (SRF). However, the complicated structure of the MRF leads to the requirement of trade-off for multi-geometrical parameters in crashworthiness design. This paper presents a systemic methodology of optimisation design of reinforced SFS under axial dynamic loading. First, the finite element analysis of the crash behaviour and the energy absorption characteristics of the MRF and the SRF are implemented. Based on the numerical results, it can be found that the specific energy absorption (SEA) of the MRF is about 22% higher than that of the SRF, and the peak crushing force (PCF) of the MRF is reduced by 12% by comparing with the SRF. The simulations show the fact that the thickness of inner stiffener and the thickness of wall frame play significant effects on the SEA and the PCF. Second, a systemic methodology of optimisation design of reinforced SFS under axial dynamic loading is developed. The multi-objective optimisation design is performed by adopting multi-objective practice swarm optimisation (MOPSO) algorithm to achieve maximum SEA capacity and minimum PCF. During the multi-objective design (MOD) process, the response surface method (RSM) is utilised to improve computational efficiency for the complicated design problem in practical engineering. Finally, the optimisation results show the potential advantages of multi-diagonal reinforced frame (MRF) and the proposed method of optimisation design guarantees the feasibility of this type of reinforced SFSs used in passenger vehicles.