Crashworthiness Research And Optimization Design Of Multi-cell Thin-walled Structure

At present, thin-walled metal tube has been widely used in impact absorbing energy dissipation system of vehicles, such as automobile, aviation and high-speed train. Due to thin-walled metal tubes collapse deformation under axial impact load are similar to the energy absorption mechanism of the frontal rail when car collision occurs. Therefore, thin-walled metal tube can be regarded as a simplified model of the frontal rail. In recent years, thin-walled multi-cell tubes showed more ideal energy absorption ability with lesser quality, has received the extensive concern of many scholars. In order to explore the thin-walled multi-cell tubes deformation mode and crashworthiness under the axial load, the following research work have been carried out in this paper:(1) Extrusion die of the five cell tube has been designed in this paper, and the five cell tube is extruded. Combined with the automobile collision safety evaluation of laws and regulations, determine the front rail simplified model—thin-walled beam structure crashworthiness evaluation indexes, through the experimental analysis of the deformation mode and energy absorption characteristics of the five cell thin-walled tubes subjected to axial load mode.(2)By implementing a numerical simulation of five cell tube under the condition of axial impact of quasi static and dynamic load, comparing the results of experiment and numerical simulation, and verifying the effectiveness and accuracy of the finite element model, this paper establishes a finite element model of reliability and validness. Based on the valid finite element model and the evolution of multi-cellular tube into a number of different cells tube under the condition of the same quality of the structure, this paper contrastively analyzes the crashworthiness of these tubes with different cells. By comparing analysis of the crashworthiness of thin-walled tube, having an further inquiry for high energy absorption characteristics of multi-cellular tube.(3)To explore the influence of the geometric parameters of five cell tube on its crashworthiness, this paper studies the wall thickness, cell size and cell connection position. The results show that the wall thickness, cell size and cell connection position will exert great influences o n the crashworthiness, and a reasonable consideration of the factors can greatly improve the crashworthiness of the structure.(4) In order to further improve the crashworthiness of multi-cellular tube under axial dynamic impact load, the optimization design was carried out on the crashworthiness of multi-cellular tube. Using full factorial experiment design method, constructing the approximate model of the objective function and constraint conditions of the crashworthiness optimization of multi-cellular tubes, and then adopting the multi-objective genetic algorithm, non-dominated sorting genetic algorithm, this paper finds the optimal solution on the Pareto front. Thus, according to different design requirements, designers can choose the optimal solutio n focusing on different crashworthiness index, which can effectively improve the structural crashworthiness.