【作者】 王斌；

【导师】 刘庆明；

【作者基本信息】 北京理工大学 ， 安全科学与工程， 2015， 硕士

【摘要】 薄壁筒体结构由于比相同截面的实心杆件弯曲强度及屈曲强度高很多，能够有效吸收冲击过程中的能量，被广泛应用于航空航天、核工业、化工工业、汽车、海洋码头以及军工业中。而这些管状构件往往管壁较薄，在撞击载荷下易发生局部凹陷变形，从而大大降低了整体的承载能力和屈曲强度。通过对薄壁筒体结构进行冲击载荷下的研究可以发现该结构的薄弱单元进而为进一步对其进行结构优化和设计提供了有效依据。基于摆臂式跌落机、应变仪、惠思登电桥以及声控触发系统建立了跌落实验的应变测试系统，通过在薄壁筒体结构表面黏贴应变片，测试了该结构于不同工况（内空、填沙）和跌落参数（跌落高度）下发生水平跌落冲击时其结构表面的应变规律。得到了薄壁筒体结构在内空和填沙两种工况下结构表面轴向方向的应变规律和环向方向的应变规律。为了尽量多的获取跌落过程中时间和空间上的连续结果，还采用有限元分析软件ANSYS/LS-DYNA对薄壁筒体结构进行跌落仿真分析，研究了结构在不同跌落条件下（跌落高度、跌落角度、筒体壁厚）的冲击响应规律，并分析该结构模型发生跌落冲击时其冲击响应参数（冲击应力、冲击加速度、冲击力）随跌落参数的变化规律，发现可以通过改变跌落姿态和适当增加壁厚来减小跌落冲击对该结构的破坏强度。通过对薄壁筒体结构在空壳和填沙两种工况下仿真结果的对比分析，发现模型的冲击响应规律在两种工况下基本相同，但是填充介质后模型发生跌落冲击时的应力、应变、冲击加速度等冲击响应参数值均有所增大，通过相同位置处加速度的实验值与仿真值的对比分析，验证了仿真模拟的正确性。最后，通过对薄壁筒体结构进行模态分析得到该结构各阶固有频率和不同固有频率下的振型，在实际应用中可以通过避免在其各阶固有频率下进行该类结构的使用，通过避免共振的发生来减轻对该结构的破坏。更多还原

【Abstract】 The bending and bucking strength of the Metal thin walled tube are much higher thansolid roads with the same cross section, so the Metal thin walled tube can effectively absorbthe impact energy. And this kind of structure is widely used in aerospace, nuclear industry,chemical industry, automobile industry and military industry. However, due to the thin wallof these compents, some local concave is easily happened under impact load, which greatlyreduces the overall carrying capacity and buckling strength. Through the research of thethin-walled cylinder under the impact load, we can find the weak unit of the structure andprovide an effective basis for the further structural optimization and design.The experimental system was established on the base of the swing arm type machine,strain gauge, bridge and acoustic control trigger system, to study the droppingcharacteristics. Through passing the strain gauge on the surface of the thin walled tubestructure, we tested the strain rule under different conditions (empty inside and filling sand)and different dropping parameters (drop height).In order to obtain the continuous results in the process of dropping as many as possible,this article does a further study of the strain rule on the surface of the thin walled tube byusing the finite element analusis software ANSYS/LS-DYNA. This article studied the ruleof shocking response under different dropping conditions (drop height, drop angle andthickness of the wall). Furthermore, this article also studied the rule of the shockingparameters (impact stress, accelation and impact force) corresponding to droppingparameters, finding that it is feasible to decrease the dropping impact strength to thestructure by changing the dropping angle or increasing the thickness of the wall. Throughthe comparison of the simulation results of the structure empty inside and filling sand, itfinds that the rule of the shock response is almost coincident. However, when the modalwas filled with medium, the parameter value of the impact stress, strain and the accelationhas dramaticlly increased. In the end, through the comparison of the accelation value of thesimulation and experiment, verifying the correctness of the simulation.Through the study of the modal analysis of thin-walled cylinder, each order naturalfrequency is obtained. We can avoid using this kind of structure under its natural frequenciy,and we can reduce the damage of the structure by avoiding the resonance phenomenon.更多还原