环形板的非轴对称屈曲分析

本文利用打靶法研究了内外边界固支且在外边界受均匀径向压力作用下的极正交各向异性环形板的非轴对称屈曲和过屈曲,计算了临界载荷,讨论了分支解的存在性,得到了分支解的渐近表达式,分析了环形板的屈曲性态。     

复合结构剪切板的屈曲与后屈曲研究

基于Ｒｅｉｓｓｎｅｒ剪切板理论，本文将现有理论模型推进了一步，导出了控制复合材料和构造矩形板平衡的广义Ｋａｒｍａｎ大挠度方程。此外，运用摄动技术，构造了一个单向压缩简支剪切矩形板的后屈曲渐近解，适用于面板和夹心材料都具正交各向异性的夹层板以及计及横向剪切变形对称铺设的层合板。文中给出了典型算例，并将当前结果与其它理论或数值解作了比较，显示出相当好的一致性。     

水平圆管中受压扭作用管桩屈曲后的解析解

首先建立了考虑自重、受水平圆管约束的管柱在压担组合作用下的屈曲方程：此方程为四阶强非线性常微分方程，难以直接精确求解；通过管柱的正弦屈由分析，找到了方程中的小参数；利用小参数摄动法求解了强非线性屈曲方程，得到了管柱螺旋屈曲后的实际屈曲构形解析解，由此可进一步得到管柱发生螺旋屈曲的临界载荷；所得解析结果与数值计算结果及本文结果退化后与文献中的相关结果比较都有良好的一致性．     

POST-BUCKLING AND IMPERFECTION SENSITIVITY OF A COLUMN WITH AN EQUILATERAL TRIANGULAR CROSS-SECTION IN THE PLASTIC RANGE

The asymmetric initial post-buckling corresponding to the lowest bifurcation load andthe imperfection sensitivity are analysed in detail for a compressed simply supported column with anequilateral triangular cross-section in the plastic range.The effect of elastic unloading is taken into ac-count in the analysis.The asymptotic relations,including high order terms,among the load,the am-plitude of imperfection and the amplitude of the bifurcation mode are realized.The results show thatthe maximum supported load is very sensitive to imperfection.     

The effect of shear deformation on the post-buckling behavior of imperfect nonlinear viscoelastic columns

Summary The post-buckling behavior of imperfect columns made of nonlinear viscoelastic materials is investigated, taking into account the effect of shear deformation. The material is modeled according to the Leaderman representation of nonlinear viscoelasticity. Solutions are developed, within the elastica and the shear deformation theories, in order to calculate the growth in time of the total deflection. The numerical results establish the importance of the shear and the nonlinear viscoelasticity effects, and of the h/ℓ ratio in the column post-buckling behavior. Accepted for publication 11 November 1996     

Post-buckling of a clamped-simply supported elastica

The complete post-buckling and large deformations of an elastica rod, one end fixed and one end pinned, is studied through perturbations near bifurcation, asymptotic analysis for large loads and a numerical integration scheme. The bifurcation curve is not monotonic. The post-buckling behavior exhibits non-linear phenomena such as limit load, non-uniqueness, hysteresis, and violent jumps.     

Thermal post-buckling analysis of square plates resting on elastic foundation: A simple closed-form solutions

Thermal post-buckling paths of homogeneous, isotropic, square plate configurations resting on elastic foundation (Winkler type) subjected to biaxial compressive thermal loads are expressed as simple closed-form solutions by using the Rayleigh–Ritz method based on coupled displacement fields. Geometric non-linearity of von-Karman type is considered. The in-plane displacement field variations used in the formulation of Rayleigh–Ritz method are derived by using the governing in-plane static differential equations of the plate which in turn simplifies the difficulty of assuming an in-plane displacement field variations of the square plate. Accuracy and robustness of the proposed closed-form solutions are demonstrated by using the non-linear finite element formulation results which are obtained from an equilibrium path approach.     

考虑弯扭形变的薄壁箱形梁的非线性后屈曲

在大位移和扭转的前提下,通过一中等弯曲扭转的位移场描述了薄壁箱形梁在偏心载荷作用下的静稳定性问题.该非线性公式可用于分析简支薄壁箱形梁在不同载荷作用下的屈曲和后屈曲行为.采用伽辽金方法将非线性微分系统离散,并通过牛顿-拉普森增量迭代法求解得代数方程组.数值计算结果表明,当前屈曲位移不可忽略时,经典的横向屈曲预测是保守的...     

周期结构后屈曲新算法及其应用

提出了周期结构后屈曲分析的一种新算法。在屈曲点附近,通过加载模型和诱导后屈曲边值问题之间的相互切换,避开屈曲点附近刚度矩阵的奇异性,并诱导结构产生预期的后屈曲变形,避免了以往后屈曲算法中引入几何初始缺陷后对系统带来的可能影响。通过对三种由超弹性材料所构成的周期孔隙结构的后屈曲分析,验证了本文所提出的后屈曲算法的有效性和灵活性。分析了周期孔隙材料多向加载对屈曲模式转换的影响,以及后屈曲变形对弹性波传播带隙的影响,为周期结构中弹性波传播的调控提供良好的基础。     

锥柱形膜片后屈曲的材料特性预示研究

使用正交表设计数值试验, 分析弹性模量、屈服强度、延伸率等材料特性参数对锥柱形膜片结构后屈曲状态的影响, 预示材料特性对膜片翻转的影响. 正交数值试验在不影响结果科学性的基础上, 极大地降低了试验次数. 数值试验结果表明: 在一定结构情况下, 弹性模量与屈服强度对膜片正向翻转影响非常显著, 而延伸率的影响与前两个因素比较而言, 几乎可以忽略. 并且, 结构顶点位移随材料的弹性模量增大而增大; 随材料的屈服强度减小而增大.因此, 在结构固定的情况下, 为了提高材料的翻转性能, 可以选择弹性模量较大而屈服强度较小的材料, 且延伸率为20%左右最好.