摘要:

AbstractIn this paper, we apply an asymptotic‐numerical method for computing the postbuckling behaviour of plate and shell structures. The bifurcating branch is sought in the form of polynomial expansions, and it is determined by solving numerically (FEM) several linear problems with a single stiffness matrix. A large number of terms of the series can easily be computed by using recurrent formulas. In comparison with a more classical step‐by‐step procedure, the method is rapid and automatic. However, the polynomial expansions have a radius of convergence which limits the validity of the solution to a neighbourhood of the bifurcation point. In the present form, the method should be viewed as a cheap and automatic way of completing a linear buckling analysis. It is illustrated in two examples: a square plate under in‐plane compression and a cylindrical shell under p

ISSN:0029-5981    

DOI:10.1002/nme.1620360802

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAn error estimate for the finite element method is presented in this paper. The error is identified as the response to a set of residual forces, and a complementary analysis provides an upper bound estimate of the global energy of the error. The inequality proposed by Babuška and Miller1is then employed to bound the error in stress and displacement at a point. The formula is derived for two‐dimensional elasticity, but the procedure is general; and can be applied to three‐dimensional and other problems. Numerical experiments using the procedure are carried out and the results are given for the four‐node bilinear compatible element and plane

ISSN:0029-5981    

DOI:10.1002/nme.1620360803

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe paper considers the elastic buckling of thick skew plates. Up to now, very little work has been done on this subject and the paper aspires to fill this gap. Based on the principle of stationary total potential energy and the recently developed pb‐2 Rayleigh‐Ritz method as a solution procedure, buckling solutions for skew plates of various aspect ratios, skew angles and boundary conditions are determined. The tabulation of these results, not available thus far, should be useful to designers and researchers who may use them as benchmark values to test the validity and convergence of their numerical techniques and softwares for thick plate analy

ISSN:0029-5981    

DOI:10.1002/nme.1620360804

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe enhanced assumed strain (EAS) method, recently proposed by Simo and Rifai13, is used to develop new four‐node membrane, plate and shell elements and eight‐node solid elements. The equivalence of certain EAS‐elements with Hellinger‐Reissner (HR) elements is discussed. For instance, the seven‐parameter element EAS‐7 with 2 × 2 integration is identical to the HR‐element of Pian and Sumihara2. Eight‐node solid elements which are free of volumetric locking and four‐node shell elements which have an improved membrane and bending behaviour, compared to the Bathe‐Dvorkin shell element7, are introduced. Numerical tests for linear elastic problems show an improved performance

ISSN:0029-5981    

DOI:10.1002/nme.1620360805

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe paper presents a displacement incrementation procedure to handle multiple loadings in post‐buckling analysis of structures by Dynamic Relaxation (DR). This procedure is generalized and a ‘variable‐arc‐length’ method is proposed to automate the tracing of load‐deflection path. The resulting algorithm exactly traces limit points and can handle ‘snap‐through’ or ‘snap‐back’ problems. The efficiency of the proposed method is demonstrated by typical examples of truss, be

ISSN:0029-5981    

DOI:10.1002/nme.1620360806

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe viscoplastic constitutive model is formulated based on the existence of the dissipation potential which embodies the notion of the gauge (Minkowski) function of the convex set. A perturbation method is used for a solution of stiff differential equations characterizing the associated problem of evolution. It relies on a discrete formulation of viscoplasticity which results from the regularized version of the principle of maximum plastic dissipation. The operator split methodology and the Newton‐Raphson method are used to obtain the numerical solution of the discretized equations of evolution. The consistent tangent modulus is expressed in a closed form as a result of the exact linearization of the discretized evolution equations. For several variants of the flow potential function, including some representative stiff functional forms, numerical tests of the integration algorithm based on iso‐error maps are provided. Finally, a numerical example is presented to illustrate the robustness and the effectiveness of the proposed appro

ISSN:0029-5981    

DOI:10.1002/nme.1620360807

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper we present an iterative penalty finite element method for viscous non‐Newtonian creeping flows. The basic idea is solving the equations for the difference between the exact solution and the solution obtained in the last iteration by the penalty method. For the case of Newtonian flows, one can show that for sufficiently small penalty parameters the iterates converge to the incompressible solution. The objective of the present work is to show that the iterative penalization can be coupled with the iterative scheme used to deal with the non‐linearity arising from the constitutive law of non‐Newtonian fluids. Some numerical experiments are conducted in order to assess the performance of the approach for fluids whose viscosity obeys the powe

ISSN:0029-5981    

DOI:10.1002/nme.1620360808

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA three‐node triangular shell element having six d.o.f. per node can be economically generated as a flat element that combines well‐known formulations for membrane stiffness and plate bending stiffness. Early elements of this type were inaccurate because the membrane response was poor. Researchers improved the membrane response by adding drilling d.o.f. and by underintegrating the membrane stiffness matrix. More recent research has dealt with the addition of membrane‐bending coupling within individual elements and the suppression of mechanisms. The present work intends to continue the improvement by modifying the membrane stiffness, simplifying the membrane‐bending coupling device and suppressing mechanisms without degrading performance or causing the mesh

ISSN:0029-5981    

DOI:10.1002/nme.1620360809

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620360810

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620360801

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY