摘要:

AbstractCost effective high precision hybrid elements are presented in a hierarchical form for vibration analysis of plates. The elements are constructed by introducing computer installed hierarchical element generator algorithms which take advantage of the exact analytical treatment of the energy integrals automatically. Additional benefits accrue from: (i) the careful selection of assumed stresses and displacements satisfying finite element requirements, and maintaining the correct stiffness rank and invariance; (ii) the ability to reduce computational costs associated with various operations and the independence with respect to element geometries, which serve to build up a methodology to handle the generation of finite elements in any general purpose finite element system efficiently. Extensive numerical studies are made to predict the natural frequencies and harmonic response of plates with different boundary conditions. Accuracy of the solutions is assessed by comparison with the well established results. The noteworthy aspects of the applications are that the proposed elements are faster than those cited previously, and show a more favourable comparison to the analytical solutions for a wider range of vibration modes by maintaining rapid convergence characteristics.

ISSN:0029-5981    

DOI:10.1002/nme.1620240902

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper contains the formulation of a space–time Sinc‐Galerkin method for the numerical solution of the parabolic partial differential equation in one space dimension. The space–time adjective means that the Galerkin technique is employed simultaneously in time and space. Salient features of the method include: exponential rate of convergence, ease of assembly of the discrete system, a global approximation and the ability to handle singular problems. Two methods of solution for the discrete system are offered and numerical results for test problems, selected from the literature, are inc

ISSN:0029-5981    

DOI:10.1002/nme.1620240903

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA finite‐element discretization of a layered stratum is considered. The response to a time‐harmonic load at a single node is calculated. For all practical purposes, the result is obtained in closed form in the case of two dimensions (line load) while the Fast Fourier Transform is employed in the three‐dimensional problem (point

ISSN:0029-5981    

DOI:10.1002/nme.1620240904

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe effect of elastic strains in the steady‐state visco‐elastic fluid flow under the rolling process is analysed quantitatively. Spurious oscillations in the stress deviator and pressure fields are precluded and the rate of convergence is improved when the Petrov–Galerkin method, which is based on a least‐square method, is introduced into the finite element equation for the constitut

ISSN:0029-5981    

DOI:10.1002/nme.1620240905

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractPlate‐bending finite elements are developed for thin and moderately thick plates. The element takes into account the influence of the transverse normal strain and the transverse shear effects. For the computation of the stresses, an additional plate element is developed to determine the inplane displacements and forces. The combined effects of the plate‐bending and inplane elements are used for the complete solution of the problem. Several examples are solved and compared with their corresponding exact soluti

ISSN:0029-5981    

DOI:10.1002/nme.1620240906

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA new functional which forms the basis of an improved hybrid element formulation is proposed. The variables for the functional include stresses, strains and displacements, and the displacements and stresses are further decomposed into two parts respectively. The proposed new formulation appears to be particularly suitable for improving conforming models.Based on this formulation, a new four‐node plane hybrid elementQcs6can be developed, and the conforming elementQ4and the non‐conforming Wilson elementQ 64and modified Wilson elementQm6can also be derived directly by this hybrid approach. It should be noted that more accurate stresses can be obtained from this element which utilizes the concept of two stress compo

ISSN:0029-5981    

DOI:10.1002/nme.1620240907

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper presents a new method for the direct computation of strongly singular integrals existing in the Cauchy principal value sense. It can be usefully applied in the solution by the direct boundary element method of many different problems. Initially, some considerations are provided in order to summarize the state‐of‐the‐art on this issue. Then the features of the proposed method are reported. The procedure allows the direct calculation of Cauchy principal value integrals with first‐order singularity and it is applicable even in advanced boundary element methods employing high‐order elements. It requires only the use of standard Gaussian quadrature formulae plus the computation of a logarithmic term. Some examples show the effectiveness and efficiency of the

ISSN:0029-5981    

DOI:10.1002/nme.1620240908

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe method of space–time finite elements enables the simple solution of quite new problems. It is possible to assume the arbitrary partition of the structure area in each moment of integration of the motion equation. Instability is caused by a too large time step and too great changes of joint locations in successive time steps. A changeable spatial partition is useful in contact dynamic problems, in the case of a travelling support, generally in problems with movable edges. In this paper a stability problem is described and some investigations for chosen types of non‐rectangular space–time finite elements are carried out. Linear and surface elements which in time space gain an additional time dimension are presented. Some numerical examples prove the efficiency of the described method under determined limita

ISSN:0029-5981    

DOI:10.1002/nme.1620240909

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe current state of the art of Finite Element Methods in Computational Fluid Dynamics is reviewed. The aim of this review is to point out what appear currently as the main shortcomings of Finite Element Methods, so as to concentrate the efforts to remove them. The analysis of flows using Finite Elements will only be successful if all steps involved in it are optimized. Therefore, I deem it necessary to describe explicit and implicit flow solvers, unstructured multigrid methods, adaptive refinement schemes, grid generation and graphics in 3‐D, the effective use of supercomputer hardware and memory, as well as the combination of structured and unstructured grid

ISSN:0029-5981    

DOI:10.1002/nme.1620240910

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractA simple and straightforward scheme for plotting contours is introduced. For any function the appropriate contours are traced on the paths of constant function values disclosing the information contained in the shape functions. The exactness of the contours matches that of the finite element analysis. Extreme value considerations must be carried out to decide whether contours appear in an element at all. Three co‐ordinate systems are dealt with: the local, the global and the screen co‐ordinate system, and the necessary mutual transformations. A short section deals with the treatment of contour discontinuities across element borders which frequently occur with stresses and heat fluxes. Finally, some examples are sh

ISSN:0029-5981    

DOI:10.1002/nme.1620240911

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY