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直杆碰撞刚性壁弹塑性动力后屈曲有限元分析 总被引:1,自引:0,他引:1
利用显式动力学有限元方法对直杆弹塑性动力后屈曲进行了分析,模拟了直杆轴向碰撞动力屈曲的变形及发展过程。分析中在直杆碰撞端局部临界屈曲长度范围内引入半正弦波形式的初始缺陷,计算结果与文献中的实验数据获得了很好的一致。分析结果表明,随着碰撞过程中所产生的应力波逐渐向前传播,后屈曲变形过程中所呈现的多个半波形式的高阶屈曲模态由初始具有单个半波形式的简单屈曲模态迅速演变而成。分析结果同时也揭示了直杆动力屈曲变形发展的机理,以及轴向应力波和屈曲变形的相互作用规律。 相似文献
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本文考虑轴向应力波效应,利用分叉理论研究各种支承半无限长弹塑性梁的动态屈曲问题。在轴向阶梯载荷和脉冲载荷冲击下得到了梁的临界屈曲载荷及初始屈曲模态。其结果与实验现象相一致。同时也为研究结构动态屈曲问题提供了有效途径。 相似文献
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轴向应力波作用下圆柱壳塑性轴对称动力屈曲 总被引:2,自引:0,他引:2
运用有限元特征值分析方法对应力波作用下圆柱壳塑性轴对称动力失稳问题进行了研究。基于应力波理论和相邻平衡准则导出了圆柱壳轴对称动力失稳时的特征方程,在分析中同时考虑了应力波效应及横向惯性效应,把圆柱壳塑性动力失稳问题归结为特征值问题。通过引入圆柱壳动力失稳时的波前约束条件实现了此类问题的有限元特征值解法。计算结果揭示了圆柱壳塑性轴对称动力屈曲变形发展的机理,以及轴向应力波和屈曲变形的相互作用规律。 相似文献
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轴向冲击下直杆动态弹塑性屈曲模态的研究 总被引:2,自引:1,他引:1
1.引言杆的动态屈曲研究开始于三十年代1966年,J. N. Goodier等人研究了飞杆对固定靶的撞击问题。由放大函数的概念求出屈曲模态。1987年H. E. Lindberg概括了国外这方面的研究工作。近年来国内也有一些工作,文[4]计及轴向应力波的影响,给出一个屈曲判据。 相似文献
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直杆动力屈曲问题研究进展 总被引:3,自引:0,他引:3
杆做为最基本的结构单元,其屈曲问题一直受到人们的极大关注,本文就这一研究领域的若干基本问题、处理方法、目前取得的成果以及人们共同关心的一些问题做一个简要的总结和评述 相似文献
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本文对结构动力屈曲的特征、分类、屈曲准则等作了一般性讨论,对流固冲击屈曲,动力屈曲的缺陷模型等作了专题讨论。最后对圆柱壳的塑性动力屈曲作了全面回顾。 相似文献
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圆柱壳撞水时的弹塑性动力屈曲研究 总被引:3,自引:0,他引:3
本文研究圆柱壳在流固中冲击载荷下的弹塑性动力曲问题。建立了液体-气体-固体三相的数学模型。其中结构部分控制方程由弹塑性力学中关于加速度的最小原理获得,本构关系采用增量理论,液体假设为不可压缩,空气层认为最等熵压缩。分别讨论了不同冲击高度时压力变化规律,屈曲对载荷的影响。屈曲沿壳长的分布及发展规律等。 相似文献
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THE DYNAMIC BUCKLING OF ELASTIC-PLASTIC COLUMN SUBJECTED TO AXIAL IMPACT BY A RIGID BODY 总被引:1,自引:0,他引:1
Han Zhijun Wang Jingchao Cheng Guoqiang Ma Hongwei Zhang Shanyuan 《Acta Mechanica Solida Sinica》2005,18(3):256-264
I. INTRODUCTIONSince the 1960s the investigation on the dynamic buckling of elastic-plastic structures under impactload has been a very active subject of study in solid mechanics. In this respect the research advanceswere summarized and reviewed from di?erent aspects by some famous scholars[1??4]. The column is themost important structural element in practical engineering. So the dynamic buckling of the column hasattracted much more attention of many researchers. Lindberg H.E. carried ou… 相似文献
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一定初缺陷杆在轴向冲击下弹塑性动态屈曲有限元计算 总被引:2,自引:0,他引:2
本文用有限元方法分析了一定初缺陷杆受轴向冲击的弹塑性动态屈曲。由变形功相关的屈曲判据求出屈曲时间,计算了初缺陷及冲击载荷形状和大小对屈曲时间的影响。 相似文献
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This paper studies the dynamic buckling behavior of multi-walled carbon nanotubes (MWNTs) subjected to step axial loading.A buckling condition is derived,and numerical results are presented for MWNTs u... 相似文献
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结构流—固冲击屈曲研究进展 总被引:8,自引:0,他引:8
本文回顾和综述结构在流-固冲击载荷作用下的动力屈曲问题的研究工作,重点分析、评述流-固冲击屈曲的特征、实验资料及已取得的成果,并展望了该领域今后的研究 相似文献
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矩形薄板流-固冲击屈曲与塑性失效的实验研究 总被引:3,自引:0,他引:3
本文对面内流-固冲击载荷作用下的四边夹支矩形薄板进行了实验研究。通过引入三种临界等效膜应变,对屈曲、塑性和塑性失效三种临界动力状态进行了定义,根据定义获得了每个试件的临界值。同时分析与观察了试件的弯曲振动模态和动力塑性失效模式。最后,探讨了弹塑性冲击历史对塑性失效状态的影响。 相似文献
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Xi Feng Liu Feng 《Acta Mechanica Solida Sinica》2005,18(4):316-325
By employing large deformation governing equations expressed in the form of finite difference, the dynamic responses of an elastic, perfectly plastic cantilever subjected to an oblique impact at its tip was numerically studied. Through analyzing the instantaneous distribution of the yield function (φ = |M/Mo| + (N/No)^2), bending moment and axial force during the early stage of the response, the elastic-plastic deformation mechanism and the influence of axial component of an oblique impact on the dynamic response of a cantilever beam were discussed. The present analysis shows that the deformation mechanism of an elastic-plastic cantilever subjected to an oblique impact consists of four phases, i.e. ‘the expanding compressed plastic region' mode; the ‘generalized traveling plastic hinge' and ‘shrinking plastic region' mixed mode; the ‘stationary plastic hinge' mode and ‘elastic vibration' mode. Compared with the two-phase deformation mode obtained by using the rigid, perfectly plastic approach, the mode of shrinking plastic region that occurred instantly after the oblique impact and the mode of stationary hinge were both confirmed. The primary features of the deformation mechanism are captured by both analysis methods. It has also been found that the beam's deformation is mainly controlled by the axial component of the oblique impact in the early phase of the dynamic response, the deformation mechanism is obviously different from the case of a transverse impact. With further development of the response, the axial component attenuates rapidly and gives negligible contribution to the yielding of the beam cross-section. At the same time, the bending moments along the cantilever develop gradually and dominate the beam's deformation. The numerical results indicate that the mass, impact speed and oblique angle are the important factors that influence the elastic-plastic dynamic response of a cantilever beam. 相似文献
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An approximate method is presented in this paper for studying the dynamic buckling of double-walled carbon nanotubes (DWNTs) under step axial load. The analysis is based on the continuum mechanics model, which takes into account the van der Waals interaction between the outer and inner nanotubes. A buckling condition is derived, from which the critical buckling load and associated buckling mode can be determined. As examples, numerical results are worked out for DWNTs under fixed boundary conditions. It is shown that, due to the effect of van der Waals forces, the critical buckling load of a DWNT is enhanced when inserting an inner tube into a single-walled one. The paper indicates that the critical buckling load of DWNTs for dynamic buckling is higher than that for static buckling. The effect of the radii is also examined. In addition, some of the results are compared with the previous ones. 相似文献
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DYNAMIC BUCKLING OF STATICALLY PRELOADED RING-STIFFENED CYLINDRICAL SHELLS UNDER AXIAL FLUID-SOLID IMPACT LOADING 总被引:1,自引:0,他引:1
The Initial Imperfection Amplified Criterion is applied to investigate the geometric nonlinear dynamic buckling of statically
preloaded ring-stiffened cylindrical shells under axial fluid-solid impact. Taking account of the effects of large deformation
and initial geometric imperfection, the governing equations are obtained by the Galerkin method and solved by the Runge-Kutta
method. The effects of static preloading (uniform external radial pressure) on the buckling features and the load-carrying
ability of ring-stiffened cylindrical shells against axial impact are discussed.
The project is supported by the National Natural Sciences Foundation of China (No. 19802017). 相似文献
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受轴向冲击有限长弹性直杆中应力波引起的分叉问题 总被引:6,自引:1,他引:6
研究了有限长理想直杆受阶跃载荷作用的弹性动力屈曲问题。将直杆的屈问题归结为由轴向应力波传播而导致的杆的分叉问题,并考虑了应力波反射的影响。给出了分叉发生的临界条件并对具体实例进行了计算。最后对阶跃载荷及脉冲载荷对杆的动力屈曲的影响进行了讨论。 相似文献