摘要:

AbstractThe one‐dimensional diffusion equation is solved using a recent class of multi‐rate numerical algorithms collectively referred to as waveform relaxation methods. The methods enable different parts or blocks in the system to take widely different time steps by decoupling the blocks in the time domain. Significant speed‐up is obtained over the results using a composite trapezoidal rule/second‐order backward Euler time‐stepping scheme without blocking. Possible implementation strategies for two‐dimensional diffusion are briefl

ISSN:1069-8299    

DOI:10.1002/cnm.1640090103

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe multiple reciprocity method (MRM) is known as a method for elimination of domain integrals appearing in the integral equation in the framework of the direct‐type boundary‐element formulation. The method employs the fundamental solution of a part of the adjoint operator corresponding to the original differential equation. In this paper we discuss the relation between the conventional integral equation formulation of the Helmholtz equation and that derived by means of the MRM formulation. The latter, formulated in terms of real‐valued variables, is proved to be a special case of the general complex‐valued form

ISSN:1069-8299    

DOI:10.1002/cnm.1640090104

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAn isoparametric plate shell element of 16 nodes and 40 degrees of freedom is developed in this paper directly from 3‐D elastic theories. In order to overcome the difficulties caused by straightforward use of a 3‐D formulation, the relative displacement method is introduced. For curved shell elements, the use of the orthogonal curvilinear co‐ordinate system greatly reduces the computer effort. The new element can conveniently solve shell problems with variable thicknesses and also easily link with other finite elements using displacement d.o.f. such as 8‐node to 21‐node 3‐D elements. Numerical examples demonstrate the efficiency of

ISSN:1069-8299    

DOI:10.1002/cnm.1640090105

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAn approximate Riemann solver is presented for the compressible flow equations with a general (convex) equation of state in a duct of variable cross‐section and within a Lagrangian frame of reference. The scheme is applied to a well‐known shock tube prob

ISSN:1069-8299    

DOI:10.1002/cnm.1640090106

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe behaviour of a Hermitian two‐node element based on the Bernoulli beam equation is examined. The assumed constraints generate rotation‐dependent distributed moments. It is shown that for these moments a potential exists, and that a rigid translation is the only rigid body mode of the element. The analysis of the Bernoulli equation demonstrates that very large values of α=e/EIenforce the conditionw,x= 0, resulting in displacements equal to zero. The element is examined for two types of constraints. The first type of constraint, diminishing rotations of a beam (α0), a highly oscillatory nature of the solution i

ISSN:1069-8299    

DOI:10.1002/cnm.1640090107

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractDiagonal mass matrices offer computational advantages in many applications. Their general use is confronted, however, with the fact that usual finite‐element formulations generate consistent mass matrices. Some methods have been suggested to diagonalize these consistent matrices. These methods are largely founded on an intuitive basis. They abandon the classical way of calculating finite‐element matrices. In an attempt to overcome this deficiency, a procedure is presented which enables direct calculation of consistent diagonal mass matrices for the isoparametric 4‐node quadrilateral and 8‐node hexahedron. This procedure is based on an expansion of the interpolation functions and the selection of an appropriate integration order. It is shown that the consistent diagonal mass and the associated stiffness matrices represent the dynamic structural properties with good a

ISSN:1069-8299    

DOI:10.1002/cnm.1640090108

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper, based on the boundary‐element technique, presents a perturbation method which can be applied to reanalysis of the eigenvalues and eigenvectors in an elastic structure. Regarding the shape changes of a structure as the perturbation of its surface nodes within the neighbourhood of the given values, this method uses the perturbation formula to obtain the eigensolutions of the modified system without solving the generalized eigenvalue problem. Finally, the authors give some sample examples to demonstrate the validity of the metho

ISSN:1069-8299    

DOI:10.1002/cnm.1640090109

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBased on the modified principle of potential energy, three triangular thin‐plate elements with nine degrees of freedom (LZ1, LZ2 and LZ3) are derived by using compatibility conditions for nodal deflection at each node and generalized compatibility conditions for average deflection and average normal slope along each side of the element. These generalized conforming elements are low‐order and high‐precision elements which pass the patch test. When overall considerations of accuracy, simplicity and reliability are taken into account, these new elements are the best 9‐DOF triangular thin‐plate elements currently

ISSN:1069-8299    

DOI:10.1002/cnm.1640090110

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractGeneralized conjugate gradient methods are often used to solve large sparse non‐symmetric linear systems. Such systems often arise in the numerical solution of convection–diffusion problems. The Lanczos/Orthodir method proposed by Jea and Young suffers the roundoff error problem. In this paper a modified Lanczos/Orthodir method is considered. The modifications are based on Paige's computational procedure and on the adaptive restarting procedure. Numerical results showed that the modified Lanczos/Orthodir method is more stable than the original version. Furthermore, with the adaptive restarting scheme the method performed much better than the Lanczos/Orthomin met

ISSN:1069-8299    

DOI:10.1002/cnm.1640090111

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1069-8299    

DOI:10.1002/cnm.1640090112

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY