自由梁受集中质量横向撞击的刚-塑性动力响应

研究自由边界的矩形截面梁在自由端和对称中面分别受到质量块横向撞击后的刚－塑性动力响应，通过完全解分析、结合数值方法给出梁的瞬态变形，并讨论输入能量、质量比等参数对梁的最终变形、移行铰消失位置及能量耗散的影响。     

刚塑性自由梁中部在横向冲击下的初始变形模式

研究了均匀矩形截面刚塑性自由梁中部在小尺寸、平头、圆柱形刚性弹体撞击下的三种变形模式,即梁的刚体平动、单铰变形模式和三铰变形模式。考虑了刚性子弹冲击后在梁上形成的剪切冲塞,分析了子弹通过冲塞作用在梁中部的剪切力可能引起的梁的弯曲变形,找出了梁的初始变形模式对子弹大小、梁的尺寸和材料性能的依赖关系。     

局部冲击作用下刚塑性平板的动力响应和失效模式

基于理想刚塑性的材料模型假定,同时考虑靶板弯曲塑性变形和剪切滑动,完整地分析了平板受刚性体撞击或受局部压力脉冲冲击的动力响应和失效模式。得到了撞击物侵彻深度、靶板穿透条件、塑性变形范围等特征变形破坏参数的解析表达式。讨论了撞击物速度、压力脉冲的冲量和形状等参量对响应和破坏模式的影响。比较了刚塑性理论分析结果与相关的实验和弹塑性数值计算结果。     

基于最小加速度原理的刚塑性动力问题

应用有限变形的最小加速度原理，推导出了小变形或有限变形构件受到刚性飞射物撞击时的刚塑性运动方程，指出该方法具有直接、简捷和可靠的特点。     

载荷作用区域对刚塑性简支梁动力响应的影响

本文研究了载荷作用区域大小对刚塑性简(固)支梁塑性动力响应的影响,得到了中、高载界限值的表达式,并对它进行了详细的讨论。文中还给出了中载和高载情况时各相的具体解答。     

刚塑性圆板受水下爆炸载荷时的动力响应

分析了简支刚塑性圆板受水下爆炸载荷时的塑性动力响应。考虑到流固耦合作用,应用Taylor平板理论求水下爆炸压力,用刚塑性法分析了圆板的永久变形场,引入膜力因子考虑了圆板大变形时的膜力效应。计算结果同用ABAQUS程序的计算结果进行了比较,表明不考虑空泡时所得结果较精确。最后考察了流固耦合作用及空泡对结构响应的影响。     

粘性介质中的长壳在冲击载荷作用下的刚塑性动力响应

本文研究了粘性介质中的固支长圆柱壳受均布冲击侧压时的塑性动力响应,得到了解析解,并对此解进行了讨论。当介质阻尼参数β趋于零时,本文结果与无阻尼解一致。文中还画出了阻尼参数及壳体的长度参数对长壳运动时间的影响曲线。     

双层扁平绕带式压力容器的刚塑性动力响应分析

采用刚塑性模型对双层长扁平绕带式压力容器受径向矩形脉冲内压作用的动力响应进行了分析,给出了结构在中载和高载作用下的变形模态、极限压力、响应时间和残余位移的表达式。计算结果表明,该种容器的静态极限压力值低于整体式压力容器的相应值;绕带层残余位移远大于其内壳和整体式压力容器的残余位移;当所受高载小于24.5 MPa时比整体式压力容器具有更强的抗冲击能力。     

金属圆柱壳受大质量低速冲击的屈曲变形

对钢质和铜质金属圆柱壳的轴向冲击动力响应进行了实验研究,记录了两种不同材料圆柱壳在大质量低速冲击下的冲击力时程曲线,得到其屈曲模态。采用高速摄像及模拟技术给出了钢质圆柱壳渐进屈曲的全过程,为理解钢质圆柱壳的屈曲机理提供了直观的结果。黄铜质圆柱壳在大质量低速冲击下, 出现整个壳面滿布屈曲波纹的塑性动力屈曲现象,说明高速冲击不是产生塑性动力屈曲的充要条件。像铜这样具有高密度的韧性材料,在大质量低速冲击下,会在轴向产生持续的压缩塑性流作用而出现塑性动力屈曲现象。     

撞击载荷下泡沫铝夹芯梁的塑性动力响应

应用泡沫金属子弹撞击加载的方式研究了固支泡沫铝夹芯梁和等质量实体梁的塑性动力响应。 采用激光测速装置和位移传感器测量了泡沫子弹的撞击速度和后面板中心点的位移-时间曲线,研究了加载 冲量、面板厚度和芯层厚度对夹芯梁抗冲击性能的影响。给出了泡沫铝夹芯梁的变形与失效模式,实验结果 表明结构响应对夹芯结构配置比较敏感,后面板中心点的残余变形与加载冲量、面板厚度呈线性关系。与等 质量实体梁的比较表明,泡沫铝夹芯梁具有更好的抗冲击能力。实验结果对多孔金属夹芯结构的优化设计具 有一定的参考价值。     

DYNAMIC RESPONSE OF A RIGID,PERFECTLY PLASTIC FREE-FREE BEAM STRUCK BY A PROJECTILE ATANY CROSS-SECTION ALONG ITS SPAN

I. INTRODUCTION The dynamic plastic response of free-free beams subjected to intense dynamic loading is a subject ofinterest for aerospace engineering applications. For example, when a rocket is attacked by a missile, itslarge plastic deformation behav…     

钝圆头质量块对简支梁的多次弹塑性撞击

考虑多次局部弹塑性接触变形行为、多次撞击和多次分离过程,提出了1种采用有限差分方法研究柔性结构多次弹塑性撞击问题的MCIS方法,研究了钝圆柱头刚性质量块水平撞击简支梁的过程。研究结果表明,该撞击过程实际上是1个复杂的多次弹塑性撞击过程,一般存在2个以上的明显撞击区,每个撞击区包含了形式多样的复杂的次生撞击过程。其他撞击区的冲量值与第1个撞击区的冲量值相当,其他撞击过程中损失的撞击动能的总和与首次撞击过程中损失的撞击动能相当,因此,多个撞击区和多次撞击过程将对梁的撞击物理行为产生重要影响。研究还发现,小质量块刚性体撞击时,首次撞击过程的撞击动能损失明显。在大质量刚性体撞击时,后续的多次撞击过程的撞击动能损失明显。 更多还原     

Dynamic large deformation response of rigid plastic arches under impact

This paper presents a theoretical analysis of the dynamic large deformation response of highly circular arches under impact. By the Instantaneous Configuration Method (ICM), the solutions of the entire large deformation response process of the problem are obtained. The influences of the mass ratio, the energy ratio and the supported condition on the final deformation, the response time and the occurrence of plastic deformation are discussed in detail. The necessary condition for occurrence of the local reverse bending phenomenon has been found. An approximate method is provided to describe the phenomenon. The numerical results are in good agreement with experimental data.     

弹性杆在刚性块轴向撞击下的动力屈曲

基于能量关系,应用功率原理对弹性杆在刚性块轴向撞击下的动力屈曲问题进行了讨论。用幂级数解法,理论上给出了该问题的级数解,同时考虑了应力波传播及反射对屈曲的影响。通过理论分析和数值计算,得到了临界速度与冲击质量以及临界时间的关系,给出了发生屈曲时的临界条件。     

ANALYSIS OF DYNAMIC RESPONSE OF AN IMPACTED ELASTIC PLATE

ＡＮＡＬＹＳＩＳＯＦＤＹＮＡＭＩＣＲＥＳＰＯＮＳＥＯＦＡＮＩＭＰＡＣＴＥＤＥＬＡＳＴＩＣＰＬＡＴＥ￥(尹邦信)ＹｉｎＢａｎｇｘｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＥｎｇｉｎｅｅｒｉｎｇ，ＳｏｕｔｈｗｅｓｔｉｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，...     

45钢动态塑性本构参量与验证

运用静态实验机和SHPB装置,对45钢在常温～750C、应变率为10-4～103 s-1下的力学行为进行了研究,拟合得到了Johnson-Cook本构模型参量。开展了Taylor圆柱撞击的火炮实验,运用LS-DYNA进行了相应的数值模拟,通过二者的比较对本构模型参量进行了验证,表明所得模型参量可以较好地描述材料在高速变形下的大应变力学行为。     

Dynamic response of a rigid plastic simply supported imperfect beam subjected to a uniform intense dynamic loading

This paper proposes a theoretical analysis for the dynamic response of a rigid perfectly plastic simply supported beam with an imperfection in the midspan cross-section under uniform step, pulse, and impulsive loading when support is assumed to be free to move inward. The complete solutions for an entire dynamic response process are given and the relationship between the distribution of energy dissipated at plastic hinges and the parameter of imperfection is also discussed.     

Experimental investigation on large deflection response of a frame impacted by a moving body

This paper reports on the experimental investigation of the dynamic large deflection response of a portal frame impacted at its midspan by a body moving at a certain speed. Both the deflection and velocity vs. time curves of the midspan and the dynamic history of a number of desired locations were recorded during the process of response. On the basis of the test data, the momentum and kinetic energy conversion between the frame and the moving body in the impact process are realized, and the occurrence and expansion of plastic regions are described. Investigation results show that the initial collision is approximately ideally inelastic, and that the elastic deformation plays a considerable role in the response though the input energy is much larger than the maximum elastic energy capacity of the beam member; therefore, in a general impact, the energy ratio should not be regarded as a sufficient criterion for a rigid—plastic solution. The ratios of the impulse transferred to and the energy absorbed by the frame in the initial collision to that carried by the moving body before impact is only related to the ratiobetween the equivalent mass of the frame paticipating in the initial collision and the mass of the impacting body, having nothing to do with the impacting velocity to a certain extent.