摘要:

AbstractA computationally efficient and accurate solution technique for large‐order eigenvalue problems with small to medium bandwidth is presented. The algorithm—called the Sub‐Polynomial Iteration (SPI) method—solves for the eigenvalues and corresponding eigenvectors. directly without any transformation to the standard form. The method is an efficient combination of several separate techniques including Sturm sequence, Lagrangian polynomial interpolation, inverse iteration with shift and Gram‐Schmidt orthogonalization. Computer run times for a set of sample solution indicate the efficiency of the S

ISSN:0029-5981    

DOI:10.1002/nme.1620171002

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA solution strategy for the analysis of nonlinear structures is described. The strategy is a simple extension of existing Newton‐type procedures, and can easily be incorporated into existing computer programs.Earlier work which contributed to the development of the strategy is reviewed and the theory of the procedure is presented. Six examples, covering several different types of structural behaviour are described. These examples suggest that the strategy is remarkably stable and efficien

ISSN:0029-5981    

DOI:10.1002/nme.1620171003

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractFormulation and applications of the hybrid‐stress finite element model to plane elasticity problems are examined. Conditions for invariance of the element stiffness are established for two‐dimensional problems, the results of which are easily extended to three‐dimensional cases. Next, the hybrid‐stress functional for a 3‐D continuum is manipulated into a more convenient form in which the location of optimal stress/strain sampling points can be identified. To illustrate these concepts, 4‐ and 8‐node plane isoparametric hybrid‐stress elements which are invariant and of correct rank are developed and compared with existing hybrid‐stress elements. For a 4‐node element, lack of invariance is shown to lead to spurious zero energy modes under appropriate element rotation. Alternative 8‐node elements are considered, and the best invariant element is shown to be one in which the stress compatibility equations are invoked. Results are also presented which demonstrate the validity of the optimal sampling points, the effects of reduced orders of numerical integration, and the behaviour of the elements for nearly inc

ISSN:0029-5981    

DOI:10.1002/nme.1620171004

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA finite element formulation to deal with the flow of metals coupled with thermal effects in presented. The deformation process of the metal is treated using the visco‐plastic flow approach and the solution technique for the coupled problem implies a simultaneous solution for velocities and temperatures. Some aspects of the numerical solution of the problem are given and in the last part of the paper some examples of steady‐state extrusion and rolling problems showing the applicability of the method are sh

ISSN:0029-5981    

DOI:10.1002/nme.1620171005

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620171006

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA numerical scheme is developed to study the stability of the linearized vorticity equations. The linear growth rates of Kelvin‐Helmholtz instabilities resulting from a velocity shear are calculated numerically. The theory of neutrally stable waves, in two dimensions, is extended to include the cases where the stream function is zero or periodic at the boundary, and is verified numerically for the case of a velocity profile having the shape of a cosine function. The instability growth rates of the oscillations in the neighbourhood of the neutrally stable waves are calculated numerically and are shown to be in very good agreement with the theory. The results are also of interest in relation to studies on the instabilities of a two‐dimensional guiding‐centre plasma, and also in the study of the diocotron instability in electr

ISSN:0029-5981    

DOI:10.1002/nme.1620171007

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThis paper presents an algorithm for obtaining a small frontwidth. This feature is of interest when employing the frontal technique for solution of systems of linear equations in the finite element method. The performance of the algorithm is assessed by several examples at the end of the paper.

ISSN:0029-5981    

DOI:10.1002/nme.1620171008

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractFor computing the collapse state of a perfect plastic continuum we suggest a mixed finite element approximation to the infinite dimensional mathematical programming problem of limit analysis. The convergence of the limit load to the exact solution is discussed, as well as solution methods for the discrete problem. Finally the method is applied to a classical problem in plane strain.

ISSN:0029-5981    

DOI:10.1002/nme.1620171009

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractTwo‐dimensional distributions and three‐dimensional element meshes are usually plotted in axonometric projection. Stereo decomposition can make the plots of complicated functions and structures more synoptical; the object appears in three dimensions. The method can be useful for the display of displacements and model shapes of three‐dimensional structures as

ISSN:0029-5981    

DOI:10.1002/nme.1620171010

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe accuracy and computational efficiency of the boundary element and the finite element methods are compared in this paper for problems of time‐dependent inelastic torsion of prismatic shafts. Several cross‐sections and two types of twisting history are considered in the numerical examples. The shaft material is assumed to obey an elastic‐time hardening creep constitutive

ISSN:0029-5981    

DOI:10.1002/nme.1620171011

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY