Research On Crashworthiness And Application Of Aluminum Multi-cell Energy Absorption Structure

The research on lightweight multicellular energy-absorbing structures provides a solution for the lightweight body and the safety of vehicle collisions.Compared with the traditional equal-thickness energy-absorbing structure,the non-equal-thickness or variable-thickness structure optimizes the utilization rate of the material and improves the lightweight and crashworthiness of the structure,which has become the focus of research in recent years.In this paper,theoretical analysis,finite element simulation and experiment are used to study the energy absorption and collapse characteristics of multi-cell energy absorption structure made of non-equal thickness aluminum,a theoretical prediction model for the average crushing force is proposed and derived.According to the passive safety protection requirements of a practical special vehicle modification design project,taking the special vehicle as the application object,the stiffness matching and optimization design of the multi-cell energy absorbing box and the body are completed.By comparing the impact effects before and after the collision,the feasibility of applying the non-equal thickness aluminum multi-cell energy-absorbing box to the collision protection of special vehicles is verified:(1)The finite element simulation of crashworthiness under quasi-static axial load is carried out for three kinds of multi-cell energy-absorbing structures with the same mass:four cells,five cells and nine cells.The deformation mode and crashworthiness of the three types of multi-cell energy-absorbing structures are compared by using the crashworthiness indexes.The results show that the five-cell energy-absorbing structure has better anti-compressibility and better energy-absorbing capacity.(2)Based on the Simple Super Folding Element theory,considering the energy absorption characteristics of different basic folding units of multicellular energy absorption structures,the derivation process of simple Super Folding Element theory is improved,and extending it from the constant thickness plate to the non-constant thickness plate,a theoretical prediction model for the average crushing force of multi-cell energy-absorbing boxes with varying cross section thickness is proposed and derived,and the theoretical,simulation and experimental results are systematically compared and analyzed.The results show that the theoretical analytical solution agrees well with the experimental results and the finite element simulation results.(3)Finite element simulation analysis is carried out for a special type of vehicle interception and collision.Analyzing the crashworthiness performance such as the longitudinal collision force curve,B-pillar acceleration curve,longitudinal energy absorption curve and longitudinal bending Angle curve of a special vehicle in the process of interception and collision.The results show that the energy absorption structure optimized in the subsequent design should meet the requirements of certain stiffness relative to the vehicle of the opposite car,meanwhile,effective deformation energy absorption should be generated relative to the collision side of our vehicle and the opposite car’s front after the stiffness increases.The initial evaluation and data collection of the crashworthiness of special vehicles are completed.(4)Based on the theoretical prediction model of average crushing force of multi-cell energy-absorbing structures with non-equal thickness,according to the crashworthiness characteristics of a certain special vehicle in intercept and collision,the stiffness matching and structural design of five cell energy-absorbing structure with non-equal thickness are carried out.And the second-generation non-dominated sorting genetic algorithm(NSGA-II)is used to conduct multi-objective optimization of its related geometric dimensions,After the installation of the five-cell energy-absorbing box,the simulation analysis of the interception and collision of two vehicles under the same working conditions is completed,crash performance of a special vehicle before and after optimization is compared.It verifies the feasibility of applying multi-cell energy absorption box to special vehicle collision protection.