星形混合多胞管的耐撞性数值与理论研究

Numerical and theoretical investigations on crashworthiness of star-shaped hybrid multi-cell tubes

为研发轻质高效的能量吸收装置,提出了基于多边形截面与星形截面混合设计的星形混合多胞管。采用数值模拟方法研究了星形混合多胞管在轴向加载条件下的吸能特性和变形模式,并结合简化超折单元理论推导了该管的平均碰撞力理论公式。研究结果表明,星形混合多胞管的多边形截面与星形截面之间产生了协同效应,额外吸收了更多的冲击动能:当多边形边数N=6时,混合截面的协同性最好;当N=8时,该管的能量吸收效率最高。在此基础上,进一步开展了几何参数分析,发现壁厚对于星形混合多胞管的耐撞性有显著的影响,碰撞力水平随着壁厚的增加而线性增长。此外,星形角度的变化对耐撞性的影响相对较小,碰撞荷载效率和比吸能随着星形角度的增加表现出先增大后减小;当星形角度α=120°时,该管拥有最佳的耐撞性。

In order to develop a lightweight and efficient energy absorption device,a novel type of the star-shaped hybrid multi-cell(SHM)tubes based on the hybrid design of polygonal cross-section and star-shaped cross-section was proposed.The finite element(FE)models of the polygonal thin-walled(PT)tubes,the star-shaped thin-walled(ST)tubes and the SHM tubes were established by ABAQUS,and the reliability of the FE model was verified by simulating quasi-static axial crush tests.Then,the energy absorption characteristics and deformation modes of three kinds of thin-walled tubes under axial loading conditions were studied by numerical simulation.Based on the simplified super folding element(SSFE)theory,the theoretical formula of the mean crushing force of the SHM tubes under the progressive folding deformation mode is established.The numerical results show that there is a synergistic effect between the polygonal cross-section and the star-shaped cross-section of the SHM tubes.Compared with the PT tubes and the ST tubes,the energy absorption of the SHM tubes is significantly improved.When the number of polygon edges N=6,the cross-section synergistic effect of the SHM tubes is the best,and the energy absorption efficiency is the highest when N=8.Subsequently,the investigations on geometric parameters of the SHM tubes are carried out,and the effects of wall thickness and star angle on crashworthiness are discussed respectively.It is found that the wall thickness has obvious influence on the crashworthiness of the SHM tubes,and the crushing force level increases linearly with the increase of the wall thickness.In addition,the change of the star angle has little influence on crashworthiness.The crushing load efficiency and the specific energy absorption increase first and then decrease with the increase of the star angles.When the star angleα=120°,the SHM tubes has the most excellent crashworthiness.The research results can provide design methods and theoretical guidance for the cross-section design of multi-cell structures.