Structure Design And Multi-Objective Optimization Of A Novel Crash Box Based On Biomimetic Structure

The crash box is a main energy-absorption part in frontal impact,therefore,it is a very important research topic that how to improve its crashworthiness through optimization design,so as to ensure the vehicle passive safety and personal property safety.In this paper,the front-end crash box is taken as the research object,and the bionic structure concept is introduced into its structural design.Based on the negative Poisson's ratio(NPR)cell structure,a novel bionic crash box is proposed,and its structure is optimized by multi-objective design method.The central content of this dissertation is focused on these points:Firstly,taking the human tibia as a bionic object,this article proposes a novel structure of the crash box.The outer shell structure of the crash box is modeled as a concave structure according to the compact bone of tibia.Meanwhile,considering the internal spongy part of tibia and structural defects of the existing positive Poisson's ratio material such as foam aluminum,the negative Poisson's ratio structure is applied to the inner filling structure of the crash box.On this basis,the simulation model of frontal impact between the rigid wall and crash box is established,and the model is validated based on RCAR regulation.Secondly,in view of the evaluation indexes of energy absorption index,cushioning capacity and compression displacement,this work fills the original quadrilateral crash box with the NPR inner core(O-F-G crash box for short),and compares the novel bionic crash box with the original quadrilateral crash box and the O-F-G crash box.The comparison results show that the crash box with positive functional gradient NPR inner core has the ideal deformation mode.On this foundation,the effects of shell thickness and thickness gradient on the crashworthiness of the novel bionic crash box are analyzed,and these lay the foundation for the subsequent research.Finally,the design variables,optimization objectives and constraints of the optimal design of the novel bionic crash box are determined.Based on this,by combining the optimal Latin hypercube design(Opt LHD)and improved response surface methodology,an approximate model between the performance indexes and design variables of the novel bionic crash box is established.In addition,archive-based micro genetic algorithm(AMGA)and improved non-dominated sorting genetic algorithm(NSGA-II)is used to search for the optimal solution set of optimization design.The findings of this study can provide theoretical basis and technical support for the development and design of crash box.