Lower Bound Limit Analysis of Three-Dimensional Elastoplastic Structures by Boundary Element Method
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摘要: 基于极限分析的下限定理,建立了用常规边界元方法进行三维理想弹塑性结构极限分析的求解算法.下限分析所需的弹性应力场可直接由边界元方法求得.所需的自平衡应力场由一组带有待定系数的自平衡应力场基矢量的线性组合进行模拟,这些自平衡应力场基矢量由边界元弹塑性迭代计算得到.下限分析问题最终被归结为一系列未知变量较少的非线性数学规划子问题并通过复合形法进行求解.给出的计算结果表明该算法有较高的精度和计算效率.Abstract: Based on the lower bound theorem of limit analysis, a solution procedure for limit analysis of three-dimensional elastoplastic structures was established using conventional boundary element method(BEM). The elastic stress field for lower bound limit analysis was computed directly by three-dimensional boundary element method(3-D BEM). The self-equilibrium stress field was constructed by the linear combination of several self-equilibrium "basis vectors" which can be computed by elastic-plastic incremental iteration of 3-D BEM analysis. The lower bound limit analysis problem was finally reduced to a series of nonlinear programming sub-problems with relatively few optimal variables. The complex method was used to solve the nonlinear programming sub-problems. The numerical results show that the present solution procedure has good accuracy and high efficiency.
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