摘要:

AbstractAn alternative quadrilateral element for Reissner—Mindlin plates, which extends the mixed formulation described in Part 1 using linked interpolations, is presented. Differently from element Q4BL presented in Part I, this element (Q4BLa) employs four internal rotation nodes and a linear approximation for transverse shear forces. It is shown that the element passes various patch tests, it does not possess any zero‐energy mode and its performance is good for both thick and thin pla

ISSN:0029-5981    

DOI:10.1002/nme.1620370902

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe focus of this paper is the accurate and efficient determination of sensitivities of electrostatic potential and charge density in charge transport problems, and the use of these sensitivities to carry out optimal design. Direct differentiations of the boundary integral formulation of Poisson's equation for charge conservation and of the non‐linear partial differential equation for current continuity are carried out to obtain equations satisfied by the sensitivities. Methods for solving the sensitivity equations are discussed. A numerical implementation of the methods is validated through several examples. It is demonstrated that the Design Sensitivity Coefficients (DSCs) of the quantities of interest in charge transport are obtained accurately and that optimal design problems can be solved efficiently using these DSC

ISSN:0029-5981    

DOI:10.1002/nme.1620370903

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractMultigrid method is used to accelerate the convergence of the numerical solution of the set of partial differential equations for generating the Body‐Fitted Co‐ordinate system (BFC) for both simply and doubly connected domain problems. The multigrid method is based on the full approximation scheme with bilinear interpolation as prolongation operator. The other components of the multigrid method such as the relaxation method, restriction operator, number of relaxation sweeps per cycle and direction of relaxation sweeps are varied with a view to obtaining the general principle in implementing an efficient multigrid algorithm for the generation of the B

ISSN:0029-5981    

DOI:10.1002/nme.1620370904

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA procedure for the optimization of stretched triangular grids is described. The method is based on the construction and minimization of a function that represents a generalized version for stretched grids of a non‐linear spring system. The function is minimized using a gradient method based on the steepest descent. Examples are provided to show the applicability of the method to computational fluid dynamics problem

ISSN:0029-5981    

DOI:10.1002/nme.1620370905

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAnalytical predictions of the postbuckling response of curved composite panels are difficult, especially under in‐plane compression, because of the presence of snap‐back with a steep negative slope beyond the bifurcation point. In this study, the pre‐ and postbuckling response of curved laminated panels with cutouts is investigated by developing a new finite element based on the free formulation. This trianguiar, flat, shell element, in conjunction with the updated Lagrangian form of the co‐rotational approach, accounts for the coupling terms arising from general material anisotropy, as well as large displacements and rotations. The analysis predictions correlate well with the corresponding experimental data available in the literature. Review of the studies in this subject area reveal that none of the available methods, including the STAGS‐C1 finite element program, is capable of providing the full description of the postbuckling phenomenon beyond bifurcation for curved composite panels with smal

ISSN:0029-5981    

DOI:10.1002/nme.1620370906

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA Finite Element Graph (FEG) is defined here as a nodal graph (G), a dual graph (G*), or a communication graph (G˙) associated with a generic finite element mesh. The Laplacian matrix (L(G),L(G*) orL(G˙)), used for the study of spectral properties of an FEG, is constructed from usual vertex and edge connectivities of a graph. An automatic algorithm, based on spectral properties of an FEG (G,G* orG˙), is proposed to reorder the nodes and/or elements of the associated finite element mesh. The new algorithm is called Spectral PEG Resequencing (SFR). This algorithm uses global information in the graph, it does not depend on a pseudoperipheral vertex in the resequencing process, and it does not use any kind of level structure of the graph. Moreover, the SFR algorithm is of special advantage in computing environments with vector and parallel processing capabilities.Nodes or elements in the mesh can be reordered depending on the use of an adequate graph representation associated with the mesh. IfGis used, then the nodes in the mesh are properly reordered for achieving profile and wavefront reduction of the finite element stiffness matrix. If eitherG* orG˙ is used, then the elements in the mesh are suitably reordered for a finite element frontai solver, A unified approach involving FEGs and finite element concepts is presented. Conclusions are inferred and possible extensions of this research are pointed out.In Part II of this work,1the computational implementation of the SFR algorithm is described and several numerical examples are presented. The examples emphasize important theoretical, numerical and practical aspects of the new resequencing met

ISSN:0029-5981    

DOI:10.1002/nme.1620370907

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn Part I of this work, Paulinoet al.1have presented an algorithm for profile and wavefront reduction of large sparse matrices of symmetric configuration. This algorithm is based on spectral properties of a Finite Element Graph (FEG), An FEG has been defined as a nodal graphG, a dual graphG* or a communication graphG˙ associated with a generic finite element mesh. The novel algorithm has been called Spectral FEG Resequencing (SFR). This algorithm has specific features that distinguish it from previous algorithms. These features include (1) use of global information in the graph, (2) no need of a pseudoperipheral vertex or the endpoints of a pseudodiameter, and (3) no need of any type of level structure of the FEG. To validate this algorithm in a numerical sense, extensive computational testing on a variety of problems is presented here. This includes algorithmic performance evaluation using a library of benchmark test problems which contains both connected and non‐connected graphs, study of the algebraic connectivity (λ2) of an FEG, eigensolver convergence verification, running time performance evaluation and assessment of the algorithm on a set of practical finite element examples. It is shown that the SFR algorithm is effective in reordering nodes and/or elements of generic finite element meshes. Moreover, it computes orderings which compare favourably with the ones obtained by some previous algorithms that have been published in the technical literat

ISSN:0029-5981    

DOI:10.1002/nme.1620370908

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractTo exploit the benefits of parallel computer architectures for multibody system simulation, an interdisciplinary approach has been pursued, combining knowledge of the three disciplines of dynamics, numerical mathematics and computer science. An analysis of the options available for the formulation and numerical solution of the dynamical system equations yielded a surprising result. A method initially proposed to solve the inverse problem of dynamics is the best choice to generate the system equations required for solving the simulation problem, when relying on implicit integration routines. Such routines have the particular advantage of handling stiff systems, too. The newO(N)‐residual formalism, generating the system equations in a form required for implicit numerical integration, has a high potential to benefit from parallel computer architectures. Two strategies of medium and coarse grain parallelization have been implemented on a Transputer network to obtain a package for parallel multibody simulation. An analysis of the performance of this package demonstrates for typical multibody simulation problems that the new code is five times faster than existing codes when implemented on a serial computer. An additional speed‐up by the same order of magnitude is obtained when the code is implemented on a Transputer netw

ISSN:0029-5981    

DOI:10.1002/nme.1620370909

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAn essentially geometric error measure capable of estimating the accuracy with which a faceted element mesh describes the continjous exact geometry of a deforming sheet is presented in this paper. This error is based on an estimated strain tensor between discrete and approximate geometries. Additionally, the paper describes the enrichment process which, at a reasonable computational cost, ensures that the error targets are met whilst generating as few elements as possible. In particular, the enrichment algorithm is based on a judicious combination of two simple operations, namely, side splitting and diagonal swapping. Finally, several applications relating to superplastic forming components are presented.

ISSN:0029-5981    

DOI:10.1002/nme.1620370910

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA multiharmonic method for analysis of non‐linear dynamic systems submitted to periodic loa conditions is presented. The approach is based on a systematic use of the fast Fourier transform. The e linearization of the resulting equations in the frequency domain allows to obtain full quadratic converg rat

ISSN:0029-5981    

DOI:10.1002/nme.1620370911

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY