摘要:

AbstractThis paper introduces an efficient boundary element approach for the analysis of thin plates, with arbitrary shapes and boundary conditions, resting on an elastic Winkler foundation. Boundary integral equations with three degrees‐of‐freedom per node are derived without unknown corner terms. A fundamental solution based upon newly defined modified Kelvin functions is formulated and it leads to a simple solution to the problem of divergent integrals. Reduction of domain loading terms for cases of distributed and concentrated loading is also provided. Case studies, including plates with free‐edge conditions, are demonstrated, and the boundary element results are compared with corresponding analytical solutions. The presented formulations provide a very accurate boundary element solution for plates with different shapes and boundary condi

ISSN:0029-5981    

DOI:10.1002/nme.1620380602

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAn algorithm for the parallel generation of 3‐D unstructured grids is presented. The technique is an extension of the algorithm presented in Reference 21 for the 2‐D case. The method uses a background grid as the means to separate spatially different regions, enabling the concurrent, parallel generation of elements in different domains and interdomain regions. The parallel 3‐D grid generator was implemented and tested on the INTEL hypercube and Touchstone Delta parallel computers. The results obtained demonstrate the effectiveness of the algorithm developed. The methodology is applicable to the parallel implementation of a wide range of problems that are, in principle, scalar by nature, and do not lend themselves to SIMD paralleliz

ISSN:0029-5981    

DOI:10.1002/nme.1620380603

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIn this paper, a geometrically non‐linear quasi‐conforming nine‐node quadrilateral degenerated solid shell element has been constructed from generalization of a linear quasi‐conforming nine‐node quadrilateral degenerated solid shell element,10based upon the non‐linear quasi‐conforming finite element method. First, the geometrical description and displacement model of the nine‐node quadrilateral degenerated solid shell element is given. Then, the non‐linear quasi‐conforming finite element method is discussed and assumed strains and weighed functions are given. Last, analysis of numerical examples for a clamped square plate, a circular arch, a spherical shell, two cylindrical shells, the patch test and a simply supported square plate is carried out. The results are compared with exact and other finite element solutions. The results indicate that the shell element in the paper is acc

ISSN:0029-5981    

DOI:10.1002/nme.1620380604

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA fully automatic general scheme is proposed to determine and analyse the intersections between two groups of surfaces composed of triangular facets. By carefully maintaining the spatial position of the lines of intersection in regenerating mesh locally around surface intersections, pieces of surfaces can be arbitrarily combined and merged. A great variety of objects can be easily created by selectively putting together different surface parts derived from surface intersections. The new algorithm is best applied in conjunction with an existing surface mesh generator to enhance its general capability in dealing with objects built from intersecting surfaces. In fact, it is a powerful surface mesh manipulator, and through the repeated use of the process, complex structures can be rapidly and accurately constructed.

ISSN:0029-5981    

DOI:10.1002/nme.1620380605

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe finite strip displacement functions for post‐local buckling are augmented with so‐called bubble functions, which are extra modes associated with internal or nodeless degrees of freedom. A non‐linear finite strip method of analysis including bubble functions is described for the post‐local buckling of geometrically imperfect plate assemblies. It is shown that the use of bubble functions improves significantly the convergence of the method. The non‐linear finite strip method is then used to study channel and I‐section members in compression

ISSN:0029-5981    

DOI:10.1002/nme.1620380606

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis work addresses finite element (FE) modelling of creep cracks under reversed and cyclic loads in steels. A constitutive model based on the creep hardening surface developed by Murakami and Ohno has been selected for this purpose. This model is particularly accurate for describing creep under reversed and cyclic loads and requires no additional material constants. An FE algorithm for this model has been derived and implemented into a research code FVP. The algorithm is verified by comparing the numerical predictions with closed form solutions for simple geometries and loading configurations. FE predictions are compared with experimental data for a stationary crack in a compact tension specimen. The stress and strain fields in the vicinity of a crack under a sustained load are compared with those for the intermediate unloading case. Several integral fracture parameters are investigated as to their appropriateness for describing creep cracks under reversed and cyclic loads.

ISSN:0029-5981    

DOI:10.1002/nme.1620380607

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractOptimal domain decomposition methods have emerged as powerful iterative algorithms for parallel implicit computations. Their key preprocessing step is mesh partitioning, where research has focused so far on the automatic generation of load‐balanced subdomains with minimum interface nodes. In this paper, we emphasize the importance of the subdomain aspect ratio as a mesh partitioning factor, and highlight its impact on the convergence rate of an optimal domain decomposition based iterative method. We also present a fast optimization algorithm for improving the aspect ratio of existing mesh partitions, and illustrate it with several examples from fluid dynamics and structural mechanics applications. For a stiffened shell problem decomposed by the optimal Recursive Spectral Bisection scheme and solved by the FETI method, this optimization algorithm is shown to improve the solution time by a factor equal to 1·54 and to restore numerical scalabili

ISSN:0029-5981    

DOI:10.1002/nme.1620380608

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe generalized integral transform technique is employed to provide hybrid numerical–analytical solutions to the non‐linear Luikov equations, that govern drying within capillary porous media. The coupled equations for moisture and temperature distributions are integral transformed to eliminate the spatial co‐ordinates, yielding an ordinary differential system for the time variation of the transformed potentials, which is readily solved through scientific subroutine libraries with automatic error control schemes. The analytical inversion formula is then recalled to provide explicit expressions for the original potentials at any desired position. The convergence behaviour of the proposed eigenfunction expansions is illustrated, and a parametric study is performed, for the drying of a slab subjected to non‐linear radiative boundary con

ISSN:0029-5981    

DOI:10.1002/nme.1620380609

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIn this paper, we present an improvement of the optimization technique of the moving asymptotes applied to a class of magnetostatic design problem. Our approach includes, among other aspects, an active set strategy which turns possible to find feasible points during the iterative process. We present some numerical results obtained on real‐life case studies where the functions are computed by a complex finite‐element rout

ISSN:0029-5981    

DOI:10.1002/nme.1620380610

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe statical behaviour of a spatial bar of an elastic and isotropic material under arbitrary distributed loads having a non‐circular helicoidal axis and cross‐section supported elastically by single and/or continuous supports is studied by the stiffness matrix method based on the complementary functions approach. By considering the geometrical compatibility conditions together with the constitutive equations and equations of equilibrium, a set of 12 first‐order differential equations having variable coefficients is obtained for spatial elements of helicoidal axes. The stiffness matrix and the element load vector of a helicoidal bar with a non‐circular axis and arbitrary cross‐section are obtained taking into consideration both the presence of an elastic support and the effects of the axial and shear deformations. For helicoidal staircases, the significance of both axial and shear deformations and eccentricities existing in wide and shallow sections are also investigated. The developed model has been coded in Fortran‐77, which has been applied to various example problems available in the relevant literature, and the results have be

ISSN:0029-5981    

DOI:10.1002/nme.1620380611

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY