摘要:

AbstractThe dynamic substructure method is extended to lightly or heavily damped systems. Both internal and external dampings are considered. The damped dynamic flexibility associated with the slave co‐ordinates is first expanded in terms of the damped fixed interface natural modes and the condensed dynamic stiffness associated with the master co‐ordinates is formed subsequently. The convergence of the condensed dynamic stiffness with respect to the damped natural modes can be improved by means of the static matrices. Since the dynamic stiffness method is equivalent to the modal synthesis method, the component mode method and Kron's method, the theory presented here is readily applicable to these methods are restricted to symmetric damping matri

ISSN:0029-5981    

DOI:10.1002/nme.1620261102

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA parallel element‐by‐element scheme is developed for finite‐element solution of elliptic boundary‐value problems. It is shown that, for a broad class of computational grids, the solution algorithm is totally parallelizable. Moreover, the conversion of an existing serial EBE code to a parallel code is seen to be quite simple. The method is implemented on the Alliant FX/8 and Sequent Balance parallel computers and ‘speedup’ performance studies are conducted for a representative elliptic PDE in two dimensions. The present procedure can be applied quite generally to other finite‐element applications, and the associated programs can be modified in a straightforward way to impleme

ISSN:0029-5981    

DOI:10.1002/nme.1620261103

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn another paper, the authors proposed an integral equation for arbitrary shaped three‐dimensional cracks. In the present paper, a discretization of this equation using a tensor formalism is formulated. This approach has the advantage of providing the displacement discontinuity vector in the local basis which varies as a function of the point of the crack surface. This also facilitates the computation of the stress intensity factors along the crack edge. Numerical examples reported for a circular crack and a semi‐elliptical surface crack in a cylindrical bar show that one can obtain good results, using few Gaussian points and no singular eleme

ISSN:0029-5981    

DOI:10.1002/nme.1620261104

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620261105

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this paper a boundary element approach is presented to establish the eigenfrequencies and the mode shapes of the free vibrations of flexible membranes with arbitrary shape. The membranes may be of homogeneous, non‐homogeneous or composite material, while their boundaries may be fixed or elastically supported. The implementation of the method is mainly based on the development of both a boundary element technique to compute numerically the Green function for the Laplace equation and a numerical procedure to solve domain integral equations using two‐dimensional Gauss integration on regions of arbitrary shape. The efficiency of the method presented is demonstrated by applying it to study the free vibrations of membranes consisting of homogeneous, non‐homogeneous and composite material, fixed or elastically supported on the boundary, and having various shapes, such as circular, rectangular, triangular, or elliptical, or being L‐shaped or of arbitrar

ISSN:0029-5981    

DOI:10.1002/nme.1620261106

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA unified numerical method to integrate stiff time‐dependent constitutive equations has been developed. This method is a stable, non‐iterative and self‐correcting solution procedure which works successfully over a wide range in strain rate sensitivity. Time steps are automatically controlled during integration to achieve a user‐specified accuracy. This method is implemented in the program package NONSS whose dual purpose is examination of the behaviour of unified constitutive models by themselves (‘one‐element behaviour’) as well as providing a computationally efficient subroutine for utilizing such models with existing finite element programs for non‐linear structural and metal forming analyses.This paper first reviews the relation between the numerical characteristic of constitutive equations and the choice of integration methods. Then the paper presents the derivation of the governing basic equations in the new method, and also derives a special algorithm which permits large integration steps within the negative strain rate sensitivity (‘serrated yielding’) regime. Examples of the program's performance are given, including plasticity at high and low temperatures, cyclic deformation and m

ISSN:0029-5981    

DOI:10.1002/nme.1620261107

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe boundary element method (BEM) is used to find the effective conductivity of a random dispersion of disks in a second material. Small separations between inclusions give rise to difficulties not usually associated with the use of the BEM. We find that the integration point spacing on a given surface element has to be of the order of the shortest distance between disks. The spacing requirement becomes a limitation at high densities, even when the ratio of the conductivity of the disks to that of the host material is close to one. This limitation is overcome by increasing the order of the integration scheme used rather than by increasing the number of surface elements. A more conventional concern is that the surface mesh itself must be sufficiently fine to represent the temperature and flux profiles. As with all simulations of dense dispersions, periodic boundary conditions have to be used and further, because random dispersions are of interest, averages of calculations over many configurations are needed. Taking account of the above considerations we calculate the first exact results for the effective conductivity of a dispersion of cylinders at a high (0.6) density. The influence of vectorization on the performance of the code is briefly mentioned, as are other possible improvements.

ISSN:0029-5981    

DOI:10.1002/nme.1620261108

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractOne approach to fully automatic mesh generation in two and three dimensions is to generate and triangulate a set of points within and on the boundary of a geometry using the properties of the Delaunay triangulation. Because the point data generate mesh topology of greater dimension, it is necessary to insure topological compatibility and perform classification of the resulting mesh with respect to the original geometry. Necessary and sufficient conditions for classification of mesh topology on three‐dimensional planar geometry are given, as well as a discussion of the more complex case of curved geometry. This paper also presents conditions to insure topological compatibility along with techniques for identifying and resolving cases of incompatibilit

ISSN:0029-5981    

DOI:10.1002/nme.1620261109

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractBoundary integral equation (boundary element) methods have the advantage over other commonly used numerical methods that they do not require values of the unknowns at points within the solution domain to be computed. Further benefits would be obtained if attention could be confined to information at one small part of the boundary, the particular region of interest in a given problem. A local boundary integral equation method based on a Taylor series expansion of the unknown function is developed to do this for two‐dimensional potential problems governed by Laplace's equation. Very accurate local values of the function and its derivatives can be obtained. The method should find particular application in the efficient refinement of approximate solutions obtained by other numerical technique

ISSN:0029-5981    

DOI:10.1002/nme.1620261110

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe paper contains a description of the finite‐element model based on Schapery's non‐linear viscoelastic constitutive equation for the adhesive, a non‐linear generalized Fickean diffusion model and an updated Lagrangian formulation of a two‐dimensional stress state, to analyse adhesively bonded joints. The finite‐element analysis program, called NOVA, is used to analyse a number of adhesive joints, and the results are compared with existing experimental results and analytical

ISSN:0029-5981    

DOI:10.1002/nme.1620261111

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY