共查询到18条相似文献,搜索用时 46 毫秒
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本文基于结构极限分析和安定分析的温度参数法,研究了线性规划的并行算法,温度参数法求解的关键是线性规划的求解效率,在分布式布储的多处理机系统上,采用了线性规划的分块单纯形法。对相当于大量工况的结构,子结构是一个很好的并行结构分析方法。 相似文献
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极限下限分析的正交基无单元Galerkin法 总被引:1,自引:0,他引:1
基于极限分析的下限定理,建立了用正交基无单元Galerkin法进行理想弹塑性结构极
限分析的整套求解算法.下限分析所需的虚拟弹性应力场可由正交基无单元Galerkin法直接
得到,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可由弹塑性增量分析中的平衡迭代得到.通过对自平衡应力场
子空间的不断修正,整个问题的求解将化为一系列非线性数学规划子问题,并通过复合形法
进行求解.算例表明该方法有效地克服了维数障碍问题,使计算效率得到了充分的提高,是
切实可行的. 相似文献
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本文应用ADINA程序对支管轴向受拉和轴向受压的T型管节点模型实例进行了非线性有限元计算.在轴向受压的工况计算中,除考虑材料的物理非线性外,还考虑了几何非线性问题.根据对计算结果的分析,确定了两种工况的极限载荷,以及支管和主管在不同载荷步下的塑性变形区的扩展情况. 相似文献
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孔洞受压的统一极限分析 总被引:1,自引:0,他引:1
采用俞茂宏统一强度理论分别就平面应变和平面应力总是对受压孔洞进行了极限分析,得到了各自的统一解形式。以往的基于Tresca、Mises、双剪屈服准则以及Mohr-Coulomb强度理论的极限解均为本文统一解的特例。此解可以适应于广泛的不同性质的各灯材料,合理也得出不同材料的相应解。 相似文献
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极限分析和安全分析的近代发展方向是寻找通用性强,计算效率高的数值方法。本文介绍将有限单元法和数学规划法相结合的、同时适用于极限分析和安全分析的统一数值方法,包括下限格式和上限格式。 相似文献
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摩擦接触弹塑性分析的数学规划法 总被引:4,自引:0,他引:4
本文提出摩擦接触弹塑性分析的数学规划法,是弹性接触问题解法的推广,使之能处理比例加载时的塑性效应。利用所导出接触问题总刚度阵的逆,结合参变量线性互补公式,仍可消去由接触单元而引入的惩罚因子。于是,可以获得一个弹塑性问题、弹性接触和弹塑性接触问题的有限元参数二次规划法模型。所选的几个实例说明了方法的实用性。 相似文献
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在极限分析理论框架体系的基础上,提出了平面滑动型岩质边坡极限分析上限法。该方法按照外力所做的功率等于内力所消耗的功率,即滑体处于极限状态时两功率相等的条件——虚功率方程,综合考虑作用在岩质边坡上的后缘裂缝静水压力、沿滑面扬压力、重力、水平地震作用力、锚固力等外力,按照强度折减法,推导得出了岩质边坡稳定性评价的极限分析上限解。锦屏一级水电站右岸泄洪洞引渠内侧工程边坡属于典型的多级台阶状岩质高边坡,该边坡岩体结构为层状结构,变形破坏模式为平面滑动。对引渠内侧岩质边坡稳定性分析结果表明,极限分析上限法对平面滑动型岩质边坡有较好的适用性。 相似文献
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《Wave Motion》2018
We present a systematic investigation of several discretization approaches for transient elastodynamic wave propagation problems. This comparison includes a Finite Difference, a Finite Volume, a Finite Element, a Spectral Element and the Scaled Boundary Finite Element Method. Numerical examples are given for simple geometries with normalized parameters, for heterogeneous materials as well as for structures with arbitrarily shaped material interfaces. General conclusions regarding the accuracy of the methods are presented. Based on the essential numerical examples an expansion of the results to a wide range of problems and thus to numerous fields of application is possible. 相似文献
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This paper presents an advanced method for a 2-dimensional analysis of transient natural convection by finite element method. The present method, based on stream function—vorticity formulation, could get rid of numerical errors and constraint of perpendicular mesh subdivision, since we excluded a finite difference approximation of vorticity on no-slip boundaries. A considerable effect of upwind weighting function was examined. The method was successfully applied to a problem of natural convection around a horizontal hot cylinder. 相似文献
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A new scheme is applied for increasing the accuracy of the penalty finite element method for incompressible flow by systematically varying from element to element the sign and magnitude of the penalty parameter λ, which enters through ?.v + p/λ = 0, an approximation to the incompressibility constraint. Not only is the error in this approximation reduced beyond that achievable with a constant λ, but also digital truncation error is lowered when it is aggravated by large variations in element size, a critical problem when the discretization must resolve thin boundary layers. The magnitude of the penalty parameter can be chosen smaller than when λ is constant, which also reduces digital truncation error; hence a shorter word-length computer is more likely to succeed. Error estimates of the method are reviewed. Boundary conditions which circumvent the hazards of aphysical pressure modes are catalogued for the finite element basis set chosen here. In order to compare performance, the variable penalty method is pitted against the conventional penalty method with constant λ in several Stokes flow case studies. 相似文献
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The paper is concerned with stability and accuracy of an nth order Lagrangian family of finite element steady-state solutions of the diffusion-convection equation, and furthermore is concerned with the stability and the accuracy of on mth kind Hermitian family of finite element solutions. We discuss the stability of the numerical solution based on the fact that the characteristic finite element solution can be expressed approximately as a rational function of cell Peclet number Pec ( = uh/k). Moreover, it is shown that by eliminating derivatives and by using the interpolation method over elements a stable solution is obtained over the domain independent of Pec for P1,3, and for P2,5 the stable solution is obtained for Pec less than 44.4. 相似文献
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Upwind collocation on Hermite cubics is compared to orthogonal collocation with respect to effective diffusion. The one-dimensional constant coefficient advection-diffusion equation is employed to this end. The effective diffusion coefficient is determined exactly and is found to be dependent on the nodal solution values. The effective diffusion coefficients of three other upwinding schemes are also presented. Upwind collocation is found to have an effective diffusion coefficient like other upwinding schemes plus an extra term which may enhance or reduce the non-advective flux, depending on the problem solution and point location within the domain. 相似文献