摘要:

AbstractA methodology is presented for measuring the effectiveness of a finite element approach when compared with a reference finite element approach with respect to accuracy and computation. The effectiveness measure is applied to the Hughes reduction method for structural eigenvalue problems and three proposed analogous methods for fluid or fluid–structure problems. Comparisons of the three methods with consistent interpolation solutions indicate that improved effectiveness can be obtaine

ISSN:0029-5981    

DOI:10.1002/nme.1620151102

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractGeometric programming is a powerful technique and its application to mechanism synthesis has not been fully explored. In this paper, slider‐crank mechanism is chosen since the objective function consists of a large number of terms while there are only two design variables. Thus the degree of difficulty is more and does not lend itself to easy application of the geometric programming. Here, modification of the objective function is suggested so that the degree of difficulty reduces to zero even when the working space constraint is imposed. This results in a near optimum solution. Application of signomial geometric programming is illustrated through a numerical exampl

ISSN:0029-5981    

DOI:10.1002/nme.1620151103

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the optimal shape design of plane or axisymmetric structures in order to minimize the stress concentration factor along the boundary. This boundary is described by straight lines and circles. The structure is analysed using the finite element method, and the optimization procedure is based on an extended interior penalty function. Three example problems are reported.

ISSN:0029-5981    

DOI:10.1002/nme.1620151104

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThe method of infinite elements is briefly reviewed. New more logical and general formulations of infinite elements are presented. The simplicity of the programming is emphasized. Results are given for elasticity and potential problems. Future extensions are discussed.

ISSN:0029-5981    

DOI:10.1002/nme.1620151105

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper is devoted to a comparison of the relative accuracy of two‐dimensional vs. three‐dimensional finite element representations of contaminant dispersion in shallow lakes. Formulations of both types are developed, followed by numerical calculations of a hypothetical lake. The results indicate that for typical lakes a two‐dimensional dispersion analysis can be employed in the absence of a significant advective contribution. With significant advection the two‐dimensional approach is not sufficiently accurate. A two‐dimensional dispersion analysis requires approximately the same computational resources as a three‐dimensional circulati

ISSN:0029-5981    

DOI:10.1002/nme.1620151106

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractTwo numerical methods for solving the problem of unsteady flow in unconfined aquifers are studied. They are an explicit finite difference method (FDM), and the finite element method (FEM). The FEM is further subdivided into three schemes: vertical displacement approach, explicit scheme (FEM1), normal velocity approach, explicit scheme (FEM2), and vertical displacement approach, implicit scheme (FEM3). Results from the above methods are compared with experimental results from a sand box model. Various factors affecting the accuracy and numerical stability are investigated. Results indicate that, for a similar degree of accuracy, the FEM requires less computational effort than the explicit FDM. Amongst the three FEM schemes, FEM3 appears to be most attractive as it is the most stable and economical of the three schemes compared.

ISSN:0029-5981    

DOI:10.1002/nme.1620151107

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractA finite element formulation for the adhesive of a lap joint is presented. The element is based on the assumptions common to the theories of Goland and Reissner and Ojalvo and Eidinoff. Deficiencies of the lap joint theories of those workers and of a previous finite element formulation of the adhesive are pointed out and the covergence of the new formulation to their results is discussed. Experimentally determined extreme fibre strains in the adherends are compared with those determined numerically using the new finite element formulation.

ISSN:0029-5981    

DOI:10.1002/nme.1620151108

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractConvection–diffusion equations are difficult to solve when the convection term dominates because most solution methods give solutions which oscillate in space. Previous criteria based on the one‐dimensional convection–diffusion equation have shown that finite difference and Galerkin (linear or quadratic basis functions) will not give oscillatory solutions provided the Peclet number times the mesh size (Pe Δx) is below a critical value. These criteria are based on the solution at the nodes, and ensure that the nodal values are monotone. Similar criteria are developed here for other methods: quadratic Galerkin with upwind weighting, cubic Galerkin, orthogonal collocation on finite elements with quadratic, cubic or quartic polynomials using Lagrangian interpolation, cubic or quartic polynominals using Hermite interpolation, and the method of moments. The nodal values do not oscillate for collocation or moments methods with Hermite cubic polynomials regardless of the value of Pe Δx.A new criterion is developed for all methods based on the monotonicity of the solutions throughout the domain. This criterion is more restrictive than one based only on the nodal values. All methods that are second order (Δx2) or better in truncation error give oscillatory solutions (based on the entire domain) unless Pe Δxis below a critical value. This value ranges from 2 for finite difference methods to 4·6 for Hermite, quartic, collocati

ISSN:0029-5981    

DOI:10.1002/nme.1620151109

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractMethods for solving the following data‐fitting problems are discussed: given the data (xi,yi,fi),i= 1,…,Nconstruct a smooth bivariate functionSwith the property thatS(xi,yi) =fii= 1,…,N. Because the desire to fit this type of data is encountered frequently in many areas of scientific applications, an investigation of the available methods for solving this problem was undertaken. Several aspects, such as computational efficiency, fitting characteristics and ease of implementation, were analysed and compared. Within the context of a general‐purpose method for large sets of data, two of these methods emerged as being generally superior to the others. It is the purpose of this paper to describe these two methods and present examples illustrating their use and appl

ISSN:0029-5981    

DOI:10.1002/nme.1620151110

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractIn one dimension, Petrov—Galerkin nonsymmetric weighting for the convective diffusion equation can be interpreted as an added dissipation. The addition of an appropriate amount of dissipation can therefore give the same oscillation‐free solutions as the ‘unwinding’, Petrov—Galerkin, finite element methods. The ‘balancing dissipation’ is optimally chosen so that excessive dissipation does not occur. A scheme is presented for extending this approach to two‐dimensional problems, and numerical examples show that the new method can be used with improved computati

ISSN:0029-5981    

DOI:10.1002/nme.1620151111

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY