摘要:

AbstractThe wave envelope method, due to Astley,1is applied to some simple propagating wave problems governed by the Helmholtz equation and similar equations. It is shown that the method yields solutions which for some of the problems are exact and for the others are approximate and complex. In these cases however, when the number of elements is increased the trial function becomes a better approximation.

ISSN:0029-5981    

DOI:10.1002/nme.1620381502

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA class of plasticity models which utilize Rankine's (principal stress) yield locus is formulated to simulate cracking in concrete and rock under monotonic loading conditions. The formulation encompasses isotropic and kinematic hardening/softening rules, and incremental (flow theory) as well as total (deformation theory) formats are considered. An Euler backward algorithm is used to integrate the stresses and internal variables over a finite loading step and an explicit expression is derived for a consistently linearized tangent stiffness matrix associated with the Euler backward scheme. Particular attention is paid to the corner regime, that is when the two major principal stresses become equal. A detailed comparison has been made of the proposed plasticity‐based crack formulations and the traditional fixed and rotating smeared‐crack models for a homogeneously stressed sample under a non‐proportional loading path. A comparison between the flow‐theory‐based plasticity crack models and experimental data has been made for a Single Edge Notched plain concrete specimen under mixed‐mode loading

ISSN:0029-5981    

DOI:10.1002/nme.1620381503

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe service life of mechanical parts, of which the gears are most important, is influenced to the greatest extent by defects occurring as cracks. In case of cracks the most important stage is the initiation and propagation of short fatigue cracks; further, the propagation of these crack up to their critical and/or permissible length also must be taken into account. As these are quite different areas we have introduced into calculations a completely new factor, i.e. the gear stress intensity factorZ. On the basis of the factorZwe have developed appropriate models, e.g. the programe STATFAG which ensures calculation of the service life of gears with and without cracks.

ISSN:0029-5981    

DOI:10.1002/nme.1620381504

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe hybrid stress method has demonstrated many improvements over conventional displacement‐based formulations. A main detraction from the method, however, has been the higher computatational cost in forming element stiffness coefficients due to matrix inversions and manipulations as required by the technique. By utilizing permissible field transformations of initially assumed stresses, a spanning set of orthonormalized stress modes can be generated which simplify the matrix equations and allow explicit expressions for element stiffness coefficients to be derived. The developed methodology is demonstrated using several selected 2‐D quadrilateral and 3‐D hexahedral ele

ISSN:0029-5981    

DOI:10.1002/nme.1620381505

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThree‐dimensional (3‐D) finite element mesh generation has been the target of automation due to the complexities associated with generating and visualizing the mesh. A fully automatic 3‐D mesh generation method is developed. The method is capable of meshing CSG solid models. It is based on modifying the classical ray‐casting technique to meet the requirements of mesh generation. The modifications include the utilization of the element size in the casting process, the utilization of 3‐D space box enclosures, and the casting of ray segments (rays with finite length). The method begins by casting ray segments into the solid. Based on the intersections between the segments and the solid boundary, the solid is discretized into cells arranged in a structure. The cell structure stores neighbourhood relations between its cells. Each cell is meshed with valid finite elements. Mesh continuity between cells is achieved via the neighbourhood relations. The last step is to process the boundary elements to represent closely the boundary. The method has been tested and applied to a number of solid models. Sample examples are

ISSN:0029-5981    

DOI:10.1002/nme.1620381506

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis article advocates a new methodology for the finite element solution of contact problems involving bodies that may undergo finite motions and deformations. The analysis is based on a decomposition of the two‐body contact problem into two simultaneous sub‐problems, and results naturally in geometrically unbiased discretization of the contacting surfaces. A proposed two‐dimensional contact element is specifically designed to unconditionally allow for exact transmission of constant normal traction through interacting sur

ISSN:0029-5981    

DOI:10.1002/nme.1620381507

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper presents a simple quadrilateral 12 DOF plate bending element based on a modified version of the hybrid‐Trefftz approach. This element makes use of two independent fields of generalized displacements:ia non‐conforming field (11 Trefftz terms for transverse displacementwand the corresponding rotations Θx, Θy) satisfying the governing differential equations of Reissner‐Mindlin theory;iian auxiliary conforming field with displacements w̃ linked to rotations\documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \Theta _x,\tilde \Theta _y$\end{document}, by the requirement of constant boundary distribution of the corresponding tangential component S̃t, of the transverse shear. This allows quadratic w̃ and linear\documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \Theta _x,\tilde \Theta _y $\end{document}, at the element boundary to be obtained with only 3 DOF at the corner nodes.The resulting element, denoted by Q̃21–11, is robust and free of shear locking in the thin limit. The numerical assessment involves comparison with several recently presented 12 DOF thick plate quadrilaterals as well as with the standard 16 DOF hybrid‐Trefftz quadrilateral, Q21‐15S, with 15 Trefftz terms and independently interpolated w̃ and\documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \Theta _x,\tilde \Theta

ISSN:0029-5981    

DOI:10.1002/nme.1620381508

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper presents the application of cubic Hermitian interpolation based finite element schemes for the time integration of the differential‐algebraic system arising in the dual reciprocity boundary element formulation of transient diffusion problems. Weighted residual procedure is used to obtain the desired recurrence relations. Numerical results presented for three representative problems involving different types of boundary conditions amply demonstrate the high accuracy of the cubic Hermitian scheme

ISSN:0029-5981    

DOI:10.1002/nme.1620381509

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620381510

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620381501

出版商:John Wiley&Sons, Ltd    

年代:1995

数据来源: WILEY