叶康生, 陆天天, 袁 驷. 结构几何非线性分析中分叉失稳的直接求解[J]. 工程力学, 2011, 28(8): 1-008.
引用本文: 叶康生, 陆天天, 袁 驷. 结构几何非线性分析中分叉失稳的直接求解[J]. 工程力学, 2011, 28(8): 1-008.
YE Kang-sheng, LU Tian-tian, YUAN Si. A DIRECT METHOD FOR THE COMPUTATION OF BIFURCATION BUCKLING IN GEOMETRIC NONLINEAR ANALYSIS OF STRUCTURES[J]. Engineering Mechanics, 2011, 28(8): 1-008.
Citation: YE Kang-sheng, LU Tian-tian, YUAN Si. A DIRECT METHOD FOR THE COMPUTATION OF BIFURCATION BUCKLING IN GEOMETRIC NONLINEAR ANALYSIS OF STRUCTURES[J]. Engineering Mechanics, 2011, 28(8): 1-008.

结构几何非线性分析中分叉失稳的直接求解

A DIRECT METHOD FOR THE COMPUTATION OF BIFURCATION BUCKLING IN GEOMETRIC NONLINEAR ANALYSIS OF STRUCTURES

  • 摘要: 在导护型牛顿法求得分叉点和分叉点上失稳模态的基础上,该文提出一个分叉路径的求解算法。将解路径上的解视为解路径弧长的连续光滑函数,由结构平衡方程对解路径弧长的一阶导数建立起分叉方向满足的控制方程。由该控制方程知,分叉点上结构结点位移向量对解路径弧长的导数可分解为分叉点上失稳模态和控制方程特解的线性组合,从而将分叉方向的求解转化为线性组合系数的求解。通过考虑结构平衡方程对解路径弧长的二阶导数与各失稳模态的向量点积,建立起线性组合系数满足的二次方程组,用牛顿法求得组合系数的解答,从而获得各分叉方向。沿各分叉方向作弧长延拓,即可从基本路径转入各分叉路径。通过跟踪各分叉路径,可对结构屈曲后的受力性能获得较全面的了解。数值算例表明该文方法准确、可靠、高效,能很好地处理大型杆系结构的分叉失稳问题。

     

    Abstract: Based on the solution of the bifurcation point and corresponding buckling modes by using the guided and guarded Newton method, this paper develops a reliable algorithm to compute the bifurcated branches. The solutions of the structural equilibrium equations are regarded as continuous functions of the arc-length of the solution path. The governing equations for the bifurcated directions are established from the first derivative of the equilibrium equations to the arc-length. Thus the first derivative of structural nodal displacement vector to the arc length along the bifurcated directions is expressed as the linear combination of the buckling modes and a special solution of these equations, which converses the bifurcated branch problem to the solution of the linear combination coefficients. A set of equations for these coefficients are set up from the dot products of the second derivative of the equilibrium equations to the arc-length with all buckling modes. These equations are solved by Newton-Raphson iteration from which the bifurcated directions are obtained. Extended along the bifurcated directions, the solution path is switched to the bifurcated branches. By tracing the bifurcated branches, the structure’s post-buckling behaviors can be obtained completely. Numerical examples show that this method is accurate, reliable and efficient, and that it can be used to the bifurcation buckling problems of large skeletal structures.

     

/

返回文章
返回