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把应力函数引入平面问题的Mises屈状条件后那个二阶非线性偏微分方程分解为两个二阶线性偏微分方程,用柯西积分公式求出这两个方程右端的已知函数,然后解这个方程,由此定出弹塑性区域的分界线和求出塑性区内的各应力分量,给出一个例题说明本文方法的应用. 相似文献
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本文利用守恒积分,对HRR奇性场的角分布函数作了进一步的探讨.证明了角分布函数满足两个函数方程.并由此导出几种新的定解方程.对于平面应变及平面应力的情况分别给出函数方程与定解方程的具体公式.最后针对若干典型情况,给出了不同定解方程的精确的数值计算结果,验证了在一般情况下不同定解方程的等价性. 相似文献
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利用复变函数理论进行地下任意开挖断面隧洞围岩应力分析的前提,是根据围岩应力边界条件方程推导出两个解析函数.从Harnack定理出发,将隧洞围岩应力边界条件方程转化成积分方程;把Laurent级数有限项表示的映射函数引入积分方程中,将以任意开挖断面为边界条件的解析函数求解转化成以单位圆周线为边界条件的求解问题.对积分方程中各被积函数在讨论域内的解析性进行了分析,在此基础上利用留数理论求解了方程中各项积分值,并获得了用来表示任意开挖断面隧道围岩应力的两个解析函数通式.给出了圆形和椭圆形隧道的两个解析函数求解算例,所获得的结果与文献中的结果一致.利用留数理论推导出的两个解析函数通式,适用于任意开挖断面隧洞的围岩应力解析解的计算,且计算过程更为简单,计算结果更为精确. 相似文献
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双周期平面弹性基本问题 总被引:4,自引:0,他引:4
郑可 《数学物理学报(A辑)》1988,(1)
周期平面弹性基本问题,路见可教授早已解决。至于双周期平面弹性问题,W.T.Koiter在基本周期胞腔仅含一个洞的情况下,对第一基本问题曾作过讨论,但是求解复应力函数时理论上有明显的漏洞,问题并没有解决。本文首先建立复应力函数的一般表达式,然后用类似于的方法,把寻求复应力函数的问题归结为求解一唯一可解的第二类Fredholm积分方程,从而完全解决了基本周期胞腔含任意个任意形状的洞的一般情况下的第一、第二基本问题。 相似文献
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在裂纹尖端的理想塑性应力分量都只是θ的函数的条件下.利用平衡方程.应力应变率关系、相容方程和屈服条件,本文导出了平面应变和反平面应变复合型裂纹尖端的理想塑性应力场的一般解析表达式.将这些一般解析表达式用于复合型裂纹.我们就可以得到Ⅰ-Ⅲ、Ⅱ-Ⅲ及Ⅰ-Ⅱ-Ⅲ复合型裂纹尖端的理想塑性应力场的解析表达式. 相似文献
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In this paper, the variational iteration method and the Adomian decomposition method are implemented to give approximate solutions for linear and nonlinear systems of differential equations of fractional order. The two methods in applied mathematics can be used as alternative methods for obtaining analytic and approximate solutions for different types of differential equations. In these schemes, the solution takes the form of a convergent series with easily computable components. This paper presents a numerical comparison between the two methods for solving systems of fractional differential equations. Numerical results show that the two approaches are easy to implement and accurate when applied to differential equations of fractional order. 相似文献
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Hermitian and skew-Hermitian splitting(HSS) method has been proved quite successfully in solving large sparse non-Hermitian positive definite systems of linear equations. Recently, by making use of HSS method as inner iteration, Newton-HSS method for solving the systems of nonlinear equations with non-Hermitian positive definite Jacobian matrices has been proposed by Bai and Guo. It has shown that the Newton-HSS method outperforms the Newton-USOR and the Newton-GMRES iteration methods. In this paper, a class of modified Newton-HSS methods for solving large systems of nonlinear equations is discussed. In our method, the modified Newton method with R-order of convergence three at least is used to solve the nonlinear equations, and the HSS method is applied to approximately solve the Newton equations. For this class of inexact Newton methods, local and semilocal convergence theorems are proved under suitable conditions. Moreover, a globally convergent modified Newton-HSS method is introduced and a basic global convergence theorem is proved. Numerical results are given to confirm the effectiveness of our method. 相似文献
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Conjugate-gradient acceleration provides a powerful tool for speeding up the convergence of a symmetrizable basic iterative method for solving a large system of linear algebraic equations with a sparse matrix. The object of this paper is to describe three generalizations of conjugate-gradient acceleration which are designed to speed up the convergence of basic iterative methods which are not necessarily symmetrizable. The application of the procedures to some commonly used basic iterative methods is described. 相似文献
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The symplectic geometry approach is introduced for accurate bending analysis of rectangular thin plates with two adjacent edges free and the others clamped or simply supported. The basic equations for rectangular plates are first transferred into Hamilton canonical equations. Using the symplectic approach, the analytic solution of rectangular thin plate with two adjacent edges simply supported and the others slidingly supported is derived. Accurate bending solutions of title problems are then obtained using the superposition method. The approach used in this paper eliminates the need to pre-determine the deformation function and is hence more reasonable than conventional methods. Numerical results are presented to demonstrate the validity and efficiency of the approach as compared with those reported in other literatures. 相似文献
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Using results of Part I of this paper, we shall now develop two methods of constructing linear partial differential equations which admit Bergman operators with polynomial kernels; these equations will be obtained explicitly. Those methods will also yield general representations of solutions of such an equation which are holomorphic in some domain of complex two-space. For generating all those solutions, one needs a pair of Bergman operators. Whereas in Part I of this paper we required at least one of the two operators to have a polynomial kernel, we now impose the condition that both operators be of that kind. This entails further basic results about the existence, construction, and uniqueness of solutions. 相似文献
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In this paper, we propose two derivative-free iterative methods for solving nonlinear monotone equations, which combines two modified HS methods with the projection method in Solodov and Svaiter (1998) [5]. The proposed methods can be applied to solve nonsmooth equations. They are suitable to large-scale equations due to their lower storage requirement. Under mild conditions, we show that the proposed methods are globally convergent. The reported numerical results show that the methods are efficient. 相似文献
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In this article, we implement relatively new analytical techniques, the variational iteration method and the Adomian decomposition method, for solving linear differential equations of fractional order. The two methods in applied mathematics can be used as alternative methods for obtaining analytic and approximate solutions for different types of fractional differential equations. In these schemes, the solution takes the form of a convergent series with easily computable components. This paper will present a numerical comparison between the two methods and a conventional method such as the fractional difference method for solving linear differential equations of fractional order. The numerical results demonstrates that the new methods are quite accurate and readily implemented. 相似文献
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In this paper square Riccati matrix differential equations are considered. The coefficients can be arbitrary time—dependent matrices and need not satisfy any symmetry conditions. Contributions to the basic problems — existence and asymptotic behaviour of solutions — are presented based on two new methods. The first one is the usage of maximum principles for second order linear differential equations, the second one is a variety of possibilities for the parametric representation of solutions of Riccati differential equations. 相似文献
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Based on homotopy, which is a basic concept in topology, a general analytic method (namely the homotopy analysis method) is proposed to obtain series solutions of nonlinear differential equations. Different from perturbation techniques, this approach is independent of small/large physical parameters. Besides, different from all previous analytic methods, it provides us with a simple way to adjust and control the convergence of solution series. Especially, it provides us with great freedom to replace a nonlinear differential equation of order n into an infinite number of linear differential equations of order k , where the order k is even unnecessary to be equal to the order n . In this paper, a nonlinear oscillation problem is used as example to describe the basic ideas of the homotopy analysis method. We illustrate that the second-order nonlinear oscillation equation can be replaced by an infinite number of (2κ)th-order linear differential equations, where κ≥ 1 can be any a positive integer. Then, the homotopy analysis method is further applied to solve a high-dimensional nonlinear differential equation with strong nonlinearity, i.e., the Gelfand equation. We illustrate that the second-order two or three-dimensional nonlinear Gelfand equation can be replaced by an infinite number of the fourth or sixth-order linear differential equations, respectively. In this way, it might be greatly simplified to solve some nonlinear problems, as illustrated in this paper. All of our series solutions agree well with numerical results. This paper illustrates that we might have much larger freedom and flexibility to solve nonlinear problems than we thought traditionally. It may keep us an open mind when solving nonlinear problems, and might bring forward some new and interesting mathematical problems to study. 相似文献
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Changyang Tang Chengjian Zhang Hai-wei Sun 《Numerical Methods for Partial Differential Equations》2023,39(1):600-621
For solving the initial-boundary value problem of two-dimensional wave equations with discrete and distributed time-variable delays, in the present paper, we first construct a class of basic one-parameter methods. In order to raise the computational efficiency of this class methods, we remold the methods as one-parameter alternating direction implicit (ADI) methods. Under the suitable conditions, the remolded methods are proved to be stable and convergent of second order in both of time and space. With several numerical experiments, the computational effectiveness and theoretical exactness of the methods are confirmed. Moreover, it is illustrated that the proposed one-parameter ADI method has the better advantage in computational efficiency than the basic one-parameter methods. 相似文献