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991.
New matrix method for analyzing vibration and damping effect of sandwich circular cylindrical shell with viscoelastic core 总被引:2,自引:0,他引:2
Based on the linear theories of thin cylindrical shells and viscoelastic materials, a governing equation describing vibration of a sandwich circular cylindrical shell with a viscoelastic core under harmonic excitation is derived. The equation can be written as a matrix differential equation of the first order, and is obtained by considering the energy dissipation due to the shear deformation of the viscoelastic core layer and the interaction between all layers. A new matrix method for solving the governing equation is then presented With an extended homogeneous capacity precision integration approach. Having obtained these, vibration characteristics and damping effect of the sandwich cylindrical shell can be studied. The method differs from a recently published work as the state vector in the governing equation is composed of displacements and internal forces of the sandwich shell rather than displacements and their derivatives. So the present method can be applied to solve dynamic problems of the kind of sandwich shells with various boundary conditions and partially constrained layer damping. Numerical examples show that the proposed approach is effective and reliable compared with the existing methods. 相似文献
992.
介绍节块内嵌离散纵标(SN)方法求解三维堆芯中子输运/扩散方程的算法框架.在基于扩散理论的三维粗网节块展开方法(NEM)的算法体系中,用基于输运理论的径向二维细网节块离散纵标方法(NDOM)的内迭代过程,替代节块展开方法(NEM)内迭代的径向求解过程.该算法充分考虑了核电厂反应堆堆芯的三维结构特点,另一方面,也充分利用了已经成熟的三维粗网节块展开方法(NEM)和二维离散纵标方法(SN)的研究成果,同时有效避免了利用离散纵标方法(SN)求解三维中子输运方程所面临的计算内存和计算时间的瓶颈问题.编制开发二维多群节块离散纵标方法(NDOM)模块程序NSNM和三维多群节块展开方法(NEM)模块程序MGNEM,并以此为基础编制开发节块内嵌SN方法的模块程序HANWIND;其中,NSNM为HANWIND求解两维问题的功能模块.针对OECD/NEA-2D C5G7MOX基准问题以及两环路核电厂三维堆芯的数值验算结果表明,节块内嵌SN方法的算法开发及程序编制有效、切实可行. 相似文献
993.
994.
本文首次使用了曲六面体带节点导数等参元,通过变分法,计算了三维机翼亚临界定常位势流中的压力分布,计算结果与试验结果符合较好,文中还例用了有限元法中的局部线性化理论,插值出元素中心点密度去处理迭代过程中元素系数阵的计算,其结果与通常的有限元计算相吻合,但计算时间却明显减少了。文章最后以有限元法的局部线性化理论和局部线性化的有限元法做了阐述。 相似文献
995.
S. Faltinsen 《BIT Numerical Mathematics》2000,40(4):652-670
Backward error analysis has proven to be very useful in stability analysis of numerical methods for ordinary differential equations. However the analysis has so far been undertaken in the Euclidean space or closed subsets thereof. In this paper we study differential equations on manifolds. We prove a backward error analysis result for intrinsic numerical methods. Especially we are interested in Lie-group methods. If the Lie algebra is nilpotent a global stability analysis can be done in the Lie algebra. In the general case we must work on the nonlinear Lie group. In order to show that there is a perturbed differential equation on the Lie group with a solution that is exponentially close to the numerical integrator after several steps, we prove a generalised version of Alekseev-Gr: obner's theorem. A major motivation for this result is that it implies many stability properties of Lie-group methods. 相似文献
996.
The Newton Iteration on Lie Groups 总被引:4,自引:0,他引:4
We define the Newton iteration for solving the equation f(y) = 0, where f is a map from a Lie group to its corresponding Lie algebra. Two versions are presented, which are formulated independently of any metric on the Lie group. Both formulations reduce to the standard method in the Euclidean case, and are related to existing algorithms on certain Riemannian manifolds. In particular, we show that, under classical assumptions on f, the proposed method converges quadratically. We illustrate the techniques by solving a fixed-point problem arising from the numerical integration of a Lie-type initial value problem via implicit Euler. 相似文献
997.
以一个广义协调元为例证明了非常规有限元与其常规对偶有限元刚度矩阵的谱等价性。该结果对非常规有限元的区域分解并行算法研究有重要作用。 相似文献
998.
Characteristic Galerkin method for convection-diffusion equations and implicit algorithm using precise integration 总被引:1,自引:0,他引:1
This paper presents a finite element procedure for solving transient, multidimensional convection-diffusion equations. The
procedure is based on the characteristic Galerkin method with an implicit algorithm using precise integration method. With
the operator splitting procedure, the precise integration method is introduced to determine the material derivative in the
convection-diffusion equation, consequently, the physical quantities of material points. An implicit algorithm with a combination
of both the precise and the traditional numerical integration procedures in time domain in the Lagrange coordinates for the
characteristic Galerkin method is formulated. The stability analysis of the algorithm shows that the unconditional stability
of present implicit algorithm is enhanced as compared with that of the traditional implicit numerical integration procedure.
The numerical results validate the presented method in solving convection-diffusion equations. As compared with SUPG method
and explicit characteristic Galerkin method, the present method gives the results with higher accuracy and better stability.
The project sponsored by the State Scientific and Technological Commission of China through “China State Key Project: the
Theory and Methodology for Scientific and Engineering Computations with Large Scale”, the National Natural Science Foundation
of China and the European Commission Research Project CI1*CT94-0014. 相似文献
999.
In this short note we prove an extension of the Euler-Maclaurin expansion for general rectangular composite quadrature rules in one dimension when the derivative of the integrand has a logarithmic singularity. We show that a correction series has to be added to the formula, but that the asymptotic expansion in powers of the discretization parameter still holds. 相似文献
1000.
In this paper we consider a Chebyshev polynomial method for the calculation of line integrals along curves with Cauchy principal
value or Hadamard finite part singularities. The major point we address is how to reconstruct the value of the integral when
the parametrization of the curve is unknown and only empirical data are available at some discrete set of nodes.
We replace the curve by a near‐minimax parametric polynomial approximation, and express the integrand by means of a sum of
Chebyshev polynomials. We make use of a mapping property of the Hadamard finite part operator to calculate the value of the
integral.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献