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This paper gives the direct formulas of stiffness matrixes of two kinds of Kirchhoffnonlinear elements under total-Lagrange coordinate.For the first one,it includes not onlythe quadric terms of increments of strain and displacement but also.the influence ofrotations.For the second one,it is simplifies and its nonlinear is considered by taking intoaccount the influence of axial force on the equilibrium epuation in the linear beam.theory.The nonlinear equation obtained from both of the above-said elements is solved bymixed Newton-Raphson method,and by comparing the results obtained from two kinds ofnonlinear beam some important conclusions that we can know how to use them right aregiven in our paper. 相似文献
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带旋转自由度C^0类任意四边形板(壳)单元 总被引:5,自引:0,他引:5
基于Reissner-Mindilin板弯曲理论和Von-Karman大挠度理论,采用单元域内和边界位移插值一致性的概念,将四节点等参弯曲单元与Allman膜变形二次插值模式相结合,对层合板壳的大挠度分析提供了一种实用的带旋转自由度的四节点C^0类板单元。大量算例表明:该单元对板壳结构的线性强度、稳定性和后屈曲分析都表现出良好的收敛性和足够的工程精度。 相似文献
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AN IMPROVED ARC-LENGTH METHOD AND APPLICATION IN THE POST-BUCKLING ANALYSIS FOR COMPOSITE STRUCTURES
Based on the conventional arc- length method, an improved arc- length method with high-efficiency is proposed. The weighted modifications with respect to the variation of structural stiffness and extra-interpolation modification by using the information of known equilibrium points are introduced to improve the incremental arc- length . An approximate expansion method for the accumulated and expected arc-length is used to ensure the convergence at given load levels in large range of applications. Numerical results show that the improved arc-length method has well adaptability and higher efficiency in the post-buckling analysis of plates and sheik structures for tracing whole load-deflection path and obtaining the convergence values at any specified load levels. 相似文献
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基于放松单元间协调条件的大变形变分原理和全局拉格朗日方法,推导了几何非线性精化三角形薄板单元。对几何刚度矩阵,通过引入特殊的单元位移函数,有效地消除了薄板弯曲问题中伴生的膜闭锁现象。数值结果表明该单元在几何非线性分析中既能消除膜闭锁又具有较高精度。 相似文献
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复合材料加筋板壳结构的后屈曲强度及破坏分析程序系统 总被引:2,自引:0,他引:2
本文介绍适用于复合材料(含各向同性材料)层合加筋板壳结构的后屈曲强度及破坏分析的程序系统的功能特点、原理和结构、通过一个受压剪载荷作用的加筋层合矩形板的破坏分析,并与试验结果作了比较,说明该程序系统的正确、可靠性。 相似文献
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吕和祥;王志必;朱菊芬 《力学与实践》1987,9(4):48-51
关于弹性力学平面问题的协调方程几乎所有的弹性力学书都有所讨论,但没有一本书把平面问题的协调方程与空间问题联系起来讨论,因为任何实际问题都是空间问题,所谓平面问题只是空间问题的一种简化。专著[1]似乎想从空间同题的协调方程讨论平面阃题的协调方程。但是我们认为专著[1]关于平面应力问题协调方程的讨论尚有不妥之处,下面提出我们 ... 相似文献
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IntroductionTheproblemofdelaminationbucklingofcompositelaminateshasgeneratedsignificantresearchinterestsandhasbeenthesubjectofmanytheoreticalinvestigationsinthisdecade.Afiniteelementmodel[1]waspresentedtosolvethepost_bucklingproblemofcompositeplateswit… 相似文献
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采用带旋转自由度参数C^0类板(壳)单元,研究复合材料箱型结构的初始屈曲性态,在推导单元几何刚度阵时,同时考虑出平面位移和面内位移对膜应变的影响;着重讨论了不同材料正方形截面梁的长细比与欧拉临界力的关系,复合材料典型盒段的截面形式和铺设角,铺设次序对初始屈曲性态的影响。 相似文献