摘要:

AbstractA mixed finite element technique is used to study the influence of yielding on buckled plates. Orthogonal anisotropic hardening is determined solely by a yield condition, which is introduced into a mixed functional for the elastic plate by Lagrange Multipliers. The Euler equations of the constrained functional include Prager's normality rule.Numerical results are given for rectangular plates of different size calculated for various material properties.

ISSN:0029-5981    

DOI:10.1002/nme.1620120501

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractBased on direct‐access programming, algorithms have been developed for the generation, and solution by Gaussian elimination of the structural stiffness matrix equation resulted from application of the finite element method in engineering analyses. A large disk storage is used to store the rows of the stiffness matrix as directly accessible records. The developed algorithm BAND2R requires only 2Nbin‐core words in implementing the Gaussian elimination whereNbis the semi‐band width of the stiffness matrix. Algorithms BANDSQ and BDSQMX are presented which requireN2bin‐core words but minimize the number of retrieving and restoring the direct‐access records during the Gaussian elimination. BANDSQ has the direct‐access feature in both the elimination and backward‐substitution steps whereas BDSQMX has the direct‐access feature only in the backward‐substitution step of the Gaussian elimination. Illustrative applications of the developed algorithms are given and the computer core and time requirements for BAND2R, BANDSQ and BDSQMX are compared to those for the conventional Gaussian elimination of using sequential, in‐core storages. Methods for reducing the semi‐band widthNbof the structural stiffness matr

ISSN:0029-5981    

DOI:10.1002/nme.1620120502

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620120503

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe difficulties associated with the solution of the skew plate buckling problem are described, and the work of other writers is summarized.By solving a numerical example, the relative advantages of two proposed refinements to the finite element displacement method are demonstrated: A technique of boundary condition relaxation appears justified and gives favourable results compared with conventional boundary condition specification. A mesh grading technique, which is simple to apply, results in a marked improvement in convergence to a solution.

ISSN:0029-5981    

DOI:10.1002/nme.1620120504

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThis paper describes two finite elements ofC1‐class defined on a tetrahedron. In order to define these elements we give the corresponding function spaces in explicit for

ISSN:0029-5981    

DOI:10.1002/nme.1620120505

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe method of modal analysis is a method widely used in structural analysis of linear systems. After a short introduction two step by step formulations for modal calculations are discussed. One of them is of more theoretical interest, the other is recommended for practical calculations for multi‐degree‐of‐freedom systems because it is efficient in computing time. The first is formulated for the whole system the latter for each mode. Likewise a combination of the method of modal analysis and the LAPLACE transformation is established. The numerical calculation of the LAPLACE transformation is done by using the algorithm of the Fast FOURIER transformation. The advantages of the different formulations for numerical calculations are disc

ISSN:0029-5981    

DOI:10.1002/nme.1620120506

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe paper presents an accelerated version of an automatic root searching technique developed by the authors for application to residual function iterative methods in vibration analysis.The power and generality of the accelerated method is demonstrated by application to (i) an 8 rotor torsional vibration system, and (ii) a 15 rotor torsional vibration system specially synthesized so as to have an uneven root distribution including clusters of close frequencies.

ISSN:0029-5981    

DOI:10.1002/nme.1620120507

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe standard implementation of the penalty function approach for the treatment of general constraint conditions in discrete systems of equations often leads to computational difficulties as the penalty weights are increased to meet constraint satisfaction tolerances. A family of iterative procedures that converges to the constrained solution for fixed weights is presented. For a discrete mechanical system, these procedures can be physically interpreted as an equilibrium iteration resulting from the appearance of corrective force patterns at the nodes of ‘constraint members’ of constant stiffness. Three forms of the iteration algorithm are studied in detail. Convergence conditions are established and the computational error propagation behaviour of the three forms is analysed. The conclusions are verified by numerical experiments on a model problem. Finally, practical guidelines concerning the implementation of the corrective process in large‐scale finite element codes are of

ISSN:0029-5981    

DOI:10.1002/nme.1620120508

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractVaried problems in the fields of operation, scheduling, allocation and design in power systems analysis can be formulated as fixed cost trans‐shipment problems. This paper indicates possible areas of application of such formulations, and by exploiting specific characteristics of certain power systems problems presents an efficient branch and bound method for solving the

ISSN:0029-5981    

DOI:10.1002/nme.1620120509

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA spectral method for modelling of tides is proposed and applied to the calculation of theM2component of the tide in the English Channel. The classical non‐linear hyperbolic problem of long wave propagation in shallow waters is transformed into a sequence of elliptic problems by looking at a multiperiodic solution the frequencies of which are previously known. The method is based upon a perturbation technique, but the principal difficulties arise from the non‐analytical form of the quadratic friction term: the main conclusions of the corresponding study only are given here, because the purpose of this paper is to present a practical application of the method to the calculation of a tidal component by the finite element method. The variational formulation of the problem is presented, and the finite element package used is described. Some results are given for theM2tide in the English Channel: cotidal maps and current fie

ISSN:0029-5981    

DOI:10.1002/nme.1620120510

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY