ISSN:0029-5981    

DOI:10.1002/nme.1620200402

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractFormulation and numerical evaluation of a shear‐flexible triangular laminated composite plate finite element is presented in this paper. The element has three nodes at its vertices, and displacements and rotations along with their first derivatives have been chosen as nodal degrees‐of‐freedom. Computation of element matrices is highly simplified by employing a shape function subroutine, and an optimal numerical integration scheme has been used to improve the performance. The element has satisfactory rate of convergence and acceptable accuracy with mesh refinement for thick as well as thin plates of both homogeneous isotropic and laminated anisotropic materials. The numerical studies also suggest that reliable prediction of the behaviour of laminated composite plates necessitates the use of higher order shear‐flexible finite element models, and the proposed finite element appears to have some advantages over available e

ISSN:0029-5981    

DOI:10.1002/nme.1620200403

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA solution technique, based on Gauss elimination, is described which can solve symmetric or unsymmetric matrices on computers with small core and disk requirement capabilities. The method is related to frontal techniques in that renumbering of the nodes, such as in a finite element mesh, is not required, and the elimination is performed immediately after the equations for a particular node have been fully summed. Only two rows of the matrix need be on core at any step of the solution, but for more efficiency, the program presented here requires all the equations associated with two nodes to be on core. Minimum disk storage is achieved by storing only nonzero entries of the matrix, a single pointing vector for each node, regardless of the number of degrees‐of‐freedom, and the use of a single sequential file. Special care is taken of the boundary nodes where only the diagonal and the right‐hand‐side vector are stored. Assembly and elimination for these nodes are avoided completely. The performance of the program is compared with both symmetric and nonsymmetric frontal routines and is shown to be acceptable. The major merit of the method lies in the fact that it can be implemented on small minicomputers. The reduction of core and disk storage inevitably increases the solution time, but the decrease in the output file size also makes the back‐substitution and resolution processes more efficient. In some cases, the total solution time can be shorter than for the frontal method due to this

ISSN:0029-5981    

DOI:10.1002/nme.1620200404

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractStarting with a mathematical statement of the convergence requirements for an element stiffness matrix, the paper discusses displacement shape functions that may be used in connection with the potential energy principle. In short, these functions must be force orthogonal and energy orthogonal, but they need not be conforming (satisfy interelement compatibility). It is shown that the requirements to the displacement functions may be greatly relaxed through slight modifications of the coupling stiffness between fundamental and higher order displacement modes. Several alternative formulations are examined. In particular, a new ‘free formulation’ is suggested. Using this form, which is very simple, the only requirement to the displacement patterns used is that they should contain the fundamental deformation modes and be linearly independent. Applications of the theory to triangular and rectangular plate bending elements are shown; the simple stiffness matrix for the latter is given explicitly. The numerical results compare favourably with other types of finite eleme

ISSN:0029-5981    

DOI:10.1002/nme.1620200405

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractAn algorithm, for use on a digital computer, is explained for cutting multiply connected regions in three‐dimensional space. The algorithm is suitable for complex electromagnetic field problems where a magnetic scalar potential, affected by current loops, is to be calculated in a multiply connected region. Problems in fluid dynamics with vorticity affecting a scalar potential, could also be attacked with this algorithm. Since finite element methods are ubiquitous in field calculations, the cuts of the space constructed by the algorithm should ideally correspond to the given discretization; this can be arranged by an application of the Lebesgue Covering Theorem, for which a second algorithm is provide

ISSN:0029-5981    

DOI:10.1002/nme.1620200406

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper deals with the application of the finite element method to the solution of propagation problems in elliptical and parabolic waveguides. Mode classification in empty waveguides is discussed, followed by extensions of the method to problems where metallic ridges lie along either major or minor axes.

ISSN:0029-5981    

DOI:10.1002/nme.1620200407

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper investigates the use of shape‐preserving interpolants based on Bernstein polynomials for the numerical solution of differential equations. A simple and accurate algorithm is presented for the integration of the initial value ordinary differential equation, as well as for the partial differential equation of the Burger typ

ISSN:0029-5981    

DOI:10.1002/nme.1620200408

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThis work presents an optimality criteria method which accurately and efficiently solves the structural optimization problem of trusses subject to deflection and stress constraints. The method is based upon the Newton–Raphson method and a first‐order approximation both for deflection and stress constraints using the method of virtual work. It solves the problem rigorously and no serious difficulties have yet been encountered in spite of the drawbacks inherent in the Newton–Raphson method. Worked examples show its superiority to other methods and its ability to cope with trusses with many members and subject to multiple constr

ISSN:0029-5981    

DOI:10.1002/nme.1620200409

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620200410

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA simple element numbering algorithm is described which yields near‐minimal frontwidths for two‐ and three‐dimensional finite element assemblies. Renumbering ofEelements requires an immediate‐access computer memory size which is proportional to the square root ofEin two‐dimensional problems, and to the two‐thirds power ofEin three dimensions. This very small memory requirement allows processing of large problems in minicomputers. When used in large computers, page‐swapping operations

ISSN:0029-5981    

DOI:10.1002/nme.1620200411

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY