列车端部双层方管组合式吸能结构耐撞性研究

Study on crash-worthiness of double-layer square tube combined energy absorbing structure at train end

为了克服现有缓冲吸能装置不能同时满足高比吸能和低撞击峰值力的问题,提出一种具有内外双层方管的组合压溃式金属薄壁方管吸能结构,该结构具有压缩效率高,吸能量大的优点。根据列车安装空间要求对吸能结构进行初步几何参数设计,建立详细的有限元模型,并进行相关数值仿真模拟。针对吸能结构设计方案进行实物样机试制,开展吸能结构轴向动态冲击试验,通过对比分析结果可知,仿真与试验的相对误差在5%以内,证明所建立的有限元模型是有效的。通过建立有限元模型对吸能结构的耐撞性能进行参数化研究,研究结果表明:所提出的组合压溃式金属薄壁方管吸能结构的压缩效率仅受单个方管壁厚的影响,相对于传统的带隔板单层金属方管,组合压溃式吸能结构充分利用了方管的内部空间,其内外双层方管结构明显增大了压缩效率与平均压溃力,从而大幅提升了轴向冲击载荷下的吸能量。对于吸能结构的初始撞击峰值力而言,诱导槽能够显著降低吸能结构在承受轴向冲击载荷时的初始撞击峰值力,随着诱导槽宽度和深度的增大,撞击峰值力呈现出明显的下降趋势。同时,隔板数目与初始撞击峰值力基本无关,但随着隔板数量的增多,吸能结构所产生的屈曲褶皱也会随之增多,吸能量逐渐增大,但隔板数量对吸能量的影响会随着其数量的增大而逐渐减弱。

This study aimed to overcome the problem that the existing energy absorption device cannot well balance the high specific energy absorption(SEA) and low impact peak force. The combined crushing styled metal thin-walled square tube energy absorption structure with inner and outer double-layer square tubes was proposed in this paper, which possessedthe advantages of high compression efficiency and large energy absorption. First, based on the requirements of train’s installation space, the preliminary geometric parameters of the energy absorbing structure were designed, the detailed finite element model was established, and the relevant numerical simulation was carried out. Then, according to the design scheme, the physical prototype was produced, and the axial dynamic impact test was carried out. By analyzing the results, it can be seen that the relative error between simulation and test is within 5%, which confirms thevalidity of the established finite element model. By parametrically studying the energy absorption capacity through the established FE model, it can be acquired that the compression efficiency of the combined crushing metal thin-walled square tube is only affected by the wall thickness of the square tube. Compared with the traditional single-layer metal square tube,the combined crushing tube makes batter use of the internal space of the square tube. The inner and outer doublelayer square tube structure significantly increases the compression efficiency and average crushing force, which greatly improves the energy absorption capacity under axial impact load. For the initial impact peak force of the energy absorbing structure, the induced groove can significantly reduce the initial impact peak force under axial impact load. Besides, with the increase of the width and depth of the induced groove, the impact peak force shows an obvious downward trend;meanwhile, the number of diaphragms is basically independent of the initial impact peak force. However, with the increase of the number of diaphragms, the buckling folds produced by the energy absorbing structure also increase, causing the increase of energy absorbing accordingly. The influence of the number of diaphragms on the energy absorbing gradually decreases with increasing number of diaphragms.