摘要:

AbstractA new method of performing the shakedown analysis of structures subjected to variable repeated loads and temperature fields is presented. The method employs the standard incremental elastic‐plastic finite element algorithm and is based upon a cyclic repetition of piecewise‐proportional paths that contain all the vertices of the load‐temperature variation domain. A numerical example illustrates the app

ISSN:0029-5981    

DOI:10.1002/nme.1620200902

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe receptance matrix of a system after a modification of rankk

ISSN:0029-5981    

DOI:10.1002/nme.1620200903

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA new family of coupled time integration operators of different orders is developed. It permits different time integration operators to be used simultaneously in various regions of the model. This approach has the advantage of applying a very accurate time integrator, such as Runge Kutta method of order two to four, to the local nonlinear region of interest and a simple time integrator, such as the implicit–explicit or mixed time implicit–explicit method of order one, for the remaining region. The computer implementation aspects, stability analysis as well as the numerical evaluations of these new methods are presented. This is another attractive addition to the repertoire of time integration meth

ISSN:0029-5981    

DOI:10.1002/nme.1620200904

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA local interpolation method for an irregular mesh of nodal points is proposed. The method is based on a Taylor expansion of the unknown function combined with the minimization of errors. Some numerical tests as well as a computer program are presented. Applicability and stability of the method are shown. By the appropirate definition of weighting coefficients, this method may be viewed as an interpolation or approximation in the sense of minimum deviation from given values. Applications in finite element and finite difference methods are shown.

ISSN:0029-5981    

DOI:10.1002/nme.1620200905

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA finite element formulation for elastoviscoplasticity problems in the presence of large strains and deformations is presented in this paper. The formulation is capable of using any of a class of combined creep‐plasticity constitutive models with state variables for the description of material behaviour. The specific problem considered is plane strain extrusion using the constitutive model originally proposed by Hart. Numerical results are presented for sample problems and the important effects of extrusion speed and friction (at the die–workpiece interface) on the residual stresses in an extruded sample are investigated. The computer program developed here is quite general and can be modified to solve problems for other manufacturing processes like rolling, sheet forming,

ISSN:0029-5981    

DOI:10.1002/nme.1620200906

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper attempts to answer two commonly raised questions during the preparation of a finite element mesh, for the linear elastic fracture analysis of cracked structure: how to set up the finite element mesh around the crack tip, and what level of accuracy is to be expected from such a modelling.Two test problems, with known analytical expressions for their stress intensity factors, are analysed by the finite element method using the isoparametric quadratic singular element. The modified parameters were the order of integration, aspect ratio, number of elements surrounding the crack tip, use of transition elements, the singular element length over the total crack length, the symmetry of the mesh around the crack tip. Based on these analyses, a data base is created and various plots produced. The results are interpreted, the accuracy evaluated and recommendations drawn.Contrary to previous reports, it is found that the computed stress intensity factor (SIF) remains within engineering accuracy (10 per cent) throughout a large range ofl/a(singular element length over crack length) for problems with a uniform non‐singular stress distribution ahead of the crack tip (i.e. double edge notch), andl/ashould be less than 0·1 for problems with a non‐singular stress gradient (i.e three‐point bend). Also, it is found that the best results are achieved by using at least four singular elements around the crack tip, with their internal angles around 45 degrees, and a reduced (2 × 2) numerical inte

ISSN:0029-5981    

DOI:10.1002/nme.1620200907

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA new direct search package is presented. Typical test functions solved establish the robustness and efficiency of the package. The most significant features of the package are that it works satisfactorily even in single precision and requires much less memory. It needs only the function values and the unidimensional search is totally dispensed with. Methods such as different descent techniques, the RMS procedure, the co‐ordinate movement technique and the gallop–canter equalization scheme form the sequence of strateg

ISSN:0029-5981    

DOI:10.1002/nme.1620200908

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper presents and analyses methods for design sensitivity analysis of static response for structural systems when general boundary conditions are used during the analysis phase. The design sensitivity analysis methods where the boundary conditions are used to reduce the equilibrium equation have been presented earlier. In such procedures, the reduced stiffness matrix is non‐singular. This fact is used to show differentiability of the displacement vector. When reduction procedures are not used, the global structural stiffness matrix may be singular. In such a case, differentiability of the displacement vector may be questionable. However, it is shown that the displacement vector is still differentiable. Several forms of the structural design sensitivity equations are presented. Although these equations are derived with Lagrange multiplier treatment of general boundary conditions, it is shown that they are applicable with any treatment of general boundary conditions. For example, they can also be used with co‐ordinate reduction schemes. Therefore, design sensitivity analysis can be carried out with any existing finite element analysis computer code. Moreover, the procedures presented can be used to calculate sensitivity of a force of constraint can that is desired. The formulations are kept quite general such that design dependent boundary conditions can be routinely treated. An example is used to illustrate the procedu

ISSN:0029-5981    

DOI:10.1002/nme.1620200909

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractIn this paper, an efficient, exact zooming technique is developed which employs static condensation and exact structural reanalysis methods. For a multiple level of zooming such that the successive level of zooming is contained within the prior levels of zoom, repeated application of static condensation will reduce the system to one that is associated only with the degrees‐of‐freedom (dof) of the original model. Then, application of an exact static reanalysis technique permits the displacements at the dof of the original model that are contained in the final zoomed portion of the structure to be obtained first. Next, the response external to the zoom, as well as the response of additional dof within various levels of zooming, can be computed. With the triangular factor of the stiffness matrix of the original system available, this approach involves only the solution of a system of equations of small order. The proposed method is demonstrated by a numerical exam

ISSN:0029-5981    

DOI:10.1002/nme.1620200910

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA new method for the formulation of hybrid elements by the Hellinger‐Reissner principle is established by expanding the essential terms of the assumed stresses as complete polynomials in the natural coordinates of the element. The equilibrium conditions are imposed in a variational sense through the internal displacements which are also expanded in the natural co‐ordinates. The resulting element possesses all the ideal qualities, i.e. it is invariant, it is less sensitive to geometric distortion, it contains a minimum number of stress parameters and it provides accurate stress calculations. For the formulation of a 4‐node plane stress element, a small perturbation method is used to determine the equilibrium constraint equations. The element has been proved to be always rank suffi

ISSN:0029-5981    

DOI:10.1002/nme.1620200911

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY