Contrastive analysis and crashworthiness optimization of two composite thin-walled structures

For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can be completely absorbed or dissipated for the aim of safety. Two composite structures(circumscribed circle structure and inscribed circle structure) were constructed. In addition, comparison and optimization of the crashworthy characteristic of the two structures were carried out based on the method of explicit finite element analysis(FEA) and Kriging surrogate model. According to the result of Kriging surrogate model, conclusions can be safely drawn that the specific energy absorption(SEA) and ratio of specific energy absorption to initial peak force(REAF) of circumscribed circle structure are lager than those of inscribed circle structure under the same design parameters. In other words, circumscribed circle structure has better performances with higher energy-absorbing ability and lower initial peak force. Besides, error analysis was adopted and the result of which indicates that the Kriging surrogate model has high nonlinear fitting precision. What is more, the SEA and REAF optimum values of the two structures have been obtained through analysis, and the crushing results have been illustrated when the two structures reach optimum SEA and REAF.     

电机轴滚花过盈配合数值模拟与试验研究

针对一种通过滚花过盈配合实现电动机刚性连接的方法进行了数值模拟分析与试验验证研究。首先建立了滚花过盈配合的三维装配模型,通过有限元方法建立了数值仿真模型,对试验部件的压入过程进行了重点分析,并利用压力试验机进行了验证试验,通过对压装试验和仿真分析的结果对比,验证了仿真模型的有效性;然后利用仿真模型,进一步分析了滚花过盈量和导向轴段过盈量对压装力以及可以传递的最大转矩的影响。所使用的方法为分析研究滚花过盈配合提供了一个有效的手段。     

基于显式有限元的薄壁结构吸能特性预测

为了探讨轴向载荷冲击作用下试验参数对薄壁结构吸能特性的影响规律，预测和分析某一类型的薄壁结构吸能特性，基于显式有限元技术建立了这一类型薄壁结构的BP人工神经网络吸能特性预测模型。以方形薄壁结构为例，通过改变结构质量、冲击速度、横截面尺寸、壁厚等影响结构吸能特性的因素对这一类型的薄壁结构进行了大量的数值试验，获得不同试验条件下的结构吸能特性参数，然后建立了这一类型薄壁结构的吸能特性预测模型，并进行自主训练学习, 当训练步数为2035时，网络模型达到误差要求。结果表明：该BP神经网络模型的输出样本与目标值十分接近, 比吸能误差值为-2.53％，有效撞击力误差值为4.67％，有效撞击行程误差值为-3.90％，说明该模型具有较好的精度。     

铝蜂窝夹层板低速冲击响应及损伤模式的参数化影响

以铝蜂窝夹层板为对象，通过低速落锤试验及包含面板、胶层及蜂窝的细节仿真模型，探究了蜂窝胞元直径、蜂窝壁厚、面板厚度及冲头半径参数影响下低速冲击响应曲线及损伤模式的变化情况，确定在试验工况下的3种损伤模式：芯层屈曲、芯层剪切及夹层板穿透，其中芯层剪切模式具有更好的吸能分布。结果表明：蜂窝胞元直径与蜂窝壁厚对冲击响应与损伤模式具有类似的影响，面板厚度增加可以较大程度地提升抗冲击性能，冲头半径的大小会显著影响损伤模式。在此基础上建立与上述参数相关的损伤模式极限载荷公式，绘制相应的损伤模式图，为铝蜂窝夹层板的抗冲击设计提供参考。