Substructure computational algorithm for exact analytic method

In[1],the exact analytic method for the solution of differential equation with variablecoefficients was suggested and an analytic expression of solution was given by initialparameter algorithm.But to some problems such as the bending,free vibration andbuckling of nonhomogeneous long cylinders,it is difficult to obtain their solutions by theinitial parameter algorithm on computer.In this paper,the substructure computationalalgorithm for the exact analytic method is presented through the bending of non-homogeneous long cylindrical shell.This substructure algorithm can be applied to solve theproblems which can not be calculated by the initial parameter algorithm on computer.Finally,the problems can be reduced to solving a low order system of algebraic equationslike the initial parameter algorithm.Numerical examples are given and compared with theinitial para-algorithm at the end of the paper,which confirms the correcthess of thesubstructure computational algorithm.     

精确解析法的子结构算法

文[1]提出精确解析法,用以求解任意变系数常微分方程,并利用初参数算法给出一个解的解析表达式.但利用初参数算法,对某一类问题,如长柱壳弯曲和振动等,它们的解将难以在计算机上得到.本文通过非均匀轴对称长圆柱壳弯曲问题,给出精确解析法的子结构算法,它能够计算初参数算法在计算机上不能解决的问题.问题最后和初参数算法一样能归结为求解一个低阶代数方程组.文末给出算例,表明本文算法的正确性,并和初参数算法作了比较.     

An exact element method for bending of nonhomogeneous thin plates

In this paper, based on the step reduction method, a new method, the exact element method for constructing finite element, is presented. Since the new method doesn't need the variational principle, it can be applied to solve non-positive and positive definite partial differential equations with arbitrary variable coefficient. By this method, a triangle noncompatible element with 6 degrees of freedom is derived to solve the bending of nonhomogeneous plate. The convergence of displacements and stress resultants which have satisfactory numerical precision is proved. Numerical examples are given at the end of this paper, which indicate satisfactory results of stress resultants and displacements can be obtained by the present method.     

A high convergent precision exact analytic method for differential equation with variable coefficients

The exact analytic method was given by[1].It can be used for arbitrary variable coefficient differential equations and the solution obtained can have the second order convergent precision.In this paper,a new high precision algorithm is given based on[1],through a bending problem of variable cross-section beams.It can have the fourth convergent precision without increasing computation work.The present computation method is not only simple but also fast.The numerical examples are given at the end of this paper which indicate that the high convergent precision can be obtained using only a few elements.The correctness of the theory in this paper is confirmed.     

非均匀圆柱壳非线性轴对称变形一般解

本文利用阶梯折算法[1],得到了非均匀圆柱壳非线性轴对称变形的一般解.文中导出了在任意轴对称载荷下求解非均匀圆柱壳非线性弯曲的位移和内力的一般公式,并给出一致收敛于精确解的证明.问题最后归结为求解二元一次代数方程组,文末给出算例.算例表明,无论内力和位移都可得到满意的结果,并收敛于精确解.     

AN EXACT ELEMENT METHOD FOR PLANE PROBLEM

In this paper,based on the step reduction method and exact analytic method a newmethod—exact element method for constructing finite element,is presented.Since the newmethod doesn’t need the variational principle,it can be applied to solve non-positive andpositive definite partial differential equations with arbitrary variable coefficient.By thismethod,a quadrilateral noncompatible element with 8 degrees of freedom is derived for thesolution of plane problem.Since Jacobi’s transformation is not applied,the present elementmay degenerate into a triangle element.It is convenient to use the element in engineering.Inthis paper,the convergence is proved.Numerical examples are given at the end of this paper,which indicate satisfactory results of stress and displacements can be obtained and havehigher numerical precision in nodes.     

高精度九节点非协调曲边三角形平面应力单元

本文利用[1]的方法,构造了一个九节点非协调三角形平面单元.与一般有限元相比可以提高一阶收敛精度,应力可直接在单元节点上得到.形成单刚矩阵时,不需要在单元域内进行数值积分,容易构造曲边单元.文末的算例表明,仅用很少的单元,位移和应力即可获得较高的精度.     

Hilbert伴随算子逆定理在有限元法中的应用

固体力学或其它学科的大量问题均归结为求解偏微分方程组。本文把 Hilbert 伴随算子逆定理用于有限元法,求解非正定和正定偏微分方程组。它可以带有任意变系数及复杂的边界条件。文小给出了收敛性证明。并给出统一的计算公式。利用本文的方法,可以给出一个非协调有限元。单元之间的协调连续条件仅需在节点上满足,因此很容易处理。和一般的有限元法相比,有更高的精度。文末给出算例,表明利用本文方法获得的解可以收敛于精确解,并有较高的收敛精度。     

THE GENERAL SOLUTION FOR DYNAMIC RESPONSE OF NONHOMOGENEOUS BEAM WITH VARIABLECROSSSECTION

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FREE VIBRATION OF NONLINEAR DEFORMATION RING-AND STRINGER-STIFFENED NONUNIFORM CYLINDRICAL SHELL

Cylindrical shells sliffened with rings and stringers are used in many structural application, (?)h as pipes conveymg fluids or gases and aerospace, In this paper, the (?)eral solution is obtained for free vibration of nonlinear deformation ring-and stringerstiffened cylindrical shell with arbitrary boundary condition by step reduction method, Finally, it is only necessary to solve a nonlinear algebraic equation. This equation is expressed as an analvtic form. Its convergence is proved. Three mumerical examples are (?)iven at the end of the paper which indicate that satisfactory results can be obtained by step reduction method.