摘要:

AbstractAn fast and effective error check for the FE stresses, based on the unit load theorem is proposed. The relative stress error is estimated by the relative error between displacements obtained by the unit load theorem and by the FE method. Analytical examples and numerical applications are presented.

ISSN:0029-5981    

DOI:10.1002/nme.1620361902

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWe discuss both linear and geometrically non‐linear finite element analysis of elastic beams, taking into account the shear deformation. In linear analysis, a novel shallow beam element formulaton is consistently derived, and the end result is more suitable for the finite element implementation than earlier attempts. The element is very resourceful for an explanation of membrane and shear locking phenomena and exploration of their possible remedies. In addition, it sheds some light on locking phenomena in non‐linear analysis. In non‐linear analysis, we discuss the finite element implementation of the finite strain beam theory of Rei

ISSN:0029-5981    

DOI:10.1002/nme.1620361903

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSeveral renumbering strategies for unstructured grids are discussed. They lead to a minimization of eache‐misses and an optimal grouping of elements for different computer platforms, from superscalar workstations to multiprocessor register‐to‐register vector machines. Timings for a typical computational fluid dynamics (CFD) code that employs these renumbering strategies indicate that CPU requirements may be halved by applying them. The renumbering strategies discussed are all of linear time complexity, making them ideally suited for applications requiring frequent mesh changes. Furthermore, these renumbering strategies are not only valid for element‐based codes but carry over to edge‐based or face‐based fi

ISSN:0029-5981    

DOI:10.1002/nme.1620361904

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractDynamic optimal design of structural systems with local non‐linearities is proposed and the corresponding mathematical programming is established in this paper. A predictor‐corrector method is presented for state and sensitivity analysis of the systems which is based on partitioning and interface prediction of linear and non‐linear regions. The non‐linear programming problem is linearized and solved by a coarse search SLP approach. A model of an automatic weapon is optimized and some interesting results are given to illustrate the effectiveness of the present

ISSN:0029-5981    

DOI:10.1002/nme.1620361905

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe boundary integral equation method is very often used to solve exterior problems of scattering of waves (elastic waves, acoustic waves, water waves and electromagnetic waves). It is known, however, that this method fails to provide a unique solution at the so‐called irregular frequencies. This difficulty is inherent to the method used rather than the nature of the problem. In the context of elastodynamics. we proposed, in a recent work1, two methods for eliminating these irregular frequencies. Both are based on modifying the fundamental solution. Here we present numerical results pertaining to the solutions of the modified and unmodified integral equation

ISSN:0029-5981    

DOI:10.1002/nme.1620361906

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper presents an efficient way to devise higher‐order hybrid elements by generalizing theadmissible matrix formulationrecently proposed by the author. The assumed stress or strain is first decomposed into the constant, lower‐ and higher‐order modes. In the absence of any higher‐order modes, the resulting hybrid element would be identical to the corresponding sub‐integrated displacement element. By a natural and straightforward method of orthogonalizing the higher‐order modes with respect to the constant and lower‐order modes, the element stiffness can be partitioned into a lower‐ and a higher‐order matrix. With further refinements, the method devised can readily be applied to a number of higher‐order hybrid elements with enhanced finite element consistency and compu

ISSN:0029-5981    

DOI:10.1002/nme.1620361907

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractQuadratic B‐spline finite elements are defined for a graded mesh. Hermite infinite elements are proposed to extend the applicability of these finite elements to unbounded regions. Test problems used to compare this technique with published procedures show that the quadratic B‐spline finite element solution has, as expected, lower error bounds than a linear element solution. These experiments also demonstrate that the Hermite infinite elements used to close the B‐spline finite element arrays lead to error norms comparable in size with other infinite element formulations.The generation of solitary waves in a semi‐infinite shallow channel by boundary forcing is modelled by the Korteweg‐de Vries equation using an array of graded elements closed by a zero pole infinite element. The resulting simulation of solitary wave motion across a non‐uniform mesh confirms existing work and illustrates the effectiveness of the present

ISSN:0029-5981    

DOI:10.1002/nme.1620361908

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper we examine the dramatic influence that a severe stretching of finite difference grids can have on the convergence behaviour of iterative methods. For the most important classes of iterative methods this phenomenon is considered for a simple model problem with various boundary conditions and an exponential grid. It is shown that grid compression near 2 Neumann boundary or in the centre can make the convergence of some methods extremely slow, whereas grid compression near a Dirichlet boundary can be very advantageous. More theoretical insight is obtained by analysing the spectrum of the Jacob: matrix for one‐ and two‐dimensional problems. Several bounds on dominant eigenvalues of this matrix are given. The final conclusions are also applicable to problems with a variable diffusion coefficient and convection‐diffusion equations solved by central difference sc

ISSN:0029-5981    

DOI:10.1002/nme.1620361909

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractMany resequencing algorithms for reducing the bandwidth, profile and wavefront of sparse symmetric matrices have been published. In finite element applications, the sparsity of a matrix is related to the nodal ordering of the finite element mesh. Some of the most successful algorithms, which are based on graph theory, require a pair of starting pseudoperipheral nodes. These nodes, located at nearly maximal distance apart, are determined using heuristic schemes. This paper presents an alternative pseadoperipheral node finder, which is based on the algorithm developed by Gibbs, Poole and Stockmeyer. This modified scheme is suitable for nodal reordering of finite meshes and provides more consistency in the effective selection of the starting nodes in problems where the selection becomes arbitrary due to the number of candidates for these starting nodes. This case arises, in particular, for square meshes. The modified scheme was implemented in Gibbs‐Poole‐Stockmeyer, Gibbs‐King and Sloan algorithms. Test problems of these modified algorithms include: (1) Everstine's 30 benchmark problems; (2) sets of square, rectangular and annular (cylindrical) finite element meshes with quadrilateral and triangular elements; and (3) additional examples originating from mesh refinement schemes. The results demonstrate that the modifications to the original algorithms contribute to the improvement of the reliability of all the resequencing algorithms tested herein for the nodal reordering of finite element m

ISSN:0029-5981    

DOI:10.1002/nme.1620361910

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA three‐dimensional infinite boundary element method for the modelling of half space contact problems is presented. The infinite surface of the half space is discretized into a finite number of elements with the elements extending to infinity mapped onto finite elements. A special mapping scheme that handles the singular integrals over those infinite boundary elements is introduced. The infinite boundary element scheme treats the effect of infinity correctly, leading to excellent accuracy which is verified for a half space subjected to uniform pressure in a circular region and a square region on the surface. The utility of the program is then illustrated through the analysis of the stress concentration at the surface of an oblate spheroidal cavity, serving as a model for a naturally occurring void, embedded in the half space subjected to normal and tangential surface traction

ISSN:0029-5981    

DOI:10.1002/nme.1620361911

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY