摘要:

AbstractThis paper illustrates the use of the theorems of geometric variation for the reanalysis of finite element structures. The formulations presented here form the basis for an efficient computer implementation.

ISSN:0029-5981    

DOI:10.1002/nme.1620261202

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA ‘family’ of tree data structures for adaptive mesh refinement is described and details concerning the associated logic are provided. The data structures encompass triangular elements and quadrilateral elements in two dimensions and quadrilateral bricks in three dimensions. Furthermore, both linear (bilinear) and quadratic (biquadratic) element types, respectively, are developed. Representative refinement results are given for the bilinear, trilinear and biquadratic types and associated performance studies made for the refinement proced

ISSN:0029-5981    

DOI:10.1002/nme.1620261203

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620261204

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe performance of the constant strain triangle with added ‘drilling’ rotations is evaluated by solving a variety of plane test problems. Numerical results confirm that the new element is always superior to the standard constant strain triangle and that it is of similar accuracy to the best available alternative triangular elements of other authors. It is, however, less accurate than some rectangular elements which include drilling rotati

ISSN:0029-5981    

DOI:10.1002/nme.1620261205

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA geometric and material non‐linear analysis procedure for framed structures is presented, using a solution algorithm of minimizing the residual displacements. This new non‐linear solution technique is believed to be the optimum in the Newton–Raphson scheme since it follows the shortest path to achieve convergence. The concept of the effective tangent stiffness matrix is introduced and is found to be efficient, simple and logical in handling the non‐linear analysis of frames with braced members and in separating multiple bifurcation

ISSN:0029-5981    

DOI:10.1002/nme.1620261206

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA steepest edge active set algorithm is described which is suitable for solving linear programming problems where the constraint matrix is sparse and has more rows than columns. The algorithm uses a steepest edge criterion for selecting the search direction at each iteration and recurrence relations are derived which enable it to execute efficiently. The canonical form for the active set method is convenient for many applications and may be exploited to devise a simple crash procedure which is employed prior to phase one. A complete two‐phase algorithm which incorporates the crash procedure is outlined. Only one artificial variable is needed to determine if the linear programming problem has a feasible solution in phase one. Some computational results are given to illustrate the effectiveness of the algorithm for a range of sparse linear programming problems. Comparisons between the steepest edge criterion and the traditional Dantzig criterion suggest that the former usually requires fewer iterations and often leads to substantial savings for large problem

ISSN:0029-5981    

DOI:10.1002/nme.1620261207

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA direct integration algorithm to solve the spatially discretized equations of motion of a structure is proposed. This algorithm formulates the equations of motion in state space and uses their analytical solution to derive a recursive discrete‐time equation. The proposed structural state procedure (SSP) can be considered as a generalization for multi‐degree‐of‐freedom systems of the Duhamel's integral used for single‐degree‐of‐freedom systems. It can be noted that the proposed SSP algorithm does not need a previous modal uncoupling of the equations of motion and consequently it does not require any hypothesis about damping. SSP is shown to be stable and to give accurate results with a reasonable computation time. Stability and accuracy essentially depend on the computation of the system matrix. The SSP algorithm is combined with an iterative scheme to obtain the response of structures with non‐linear behaviour. Two examples of application of SSP are included: seismic response of a building structure with linear behaviour and free vibration of a non‐linear system with imposed i

ISSN:0029-5981    

DOI:10.1002/nme.1620261208

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractOften industrial codes for the numerical integration of the 2D shallow water equations are based on an Alternating Direction Implicit method. However, for large time steps these codes suffer from inaccuracies when dealing with a complex geometry or bathymetry. This reduces the performance considerably. In this paper a new method is presented in which these inaccuracies are absent, even for large time steps. The method is a fully implicit time integration method. In order to obtain linear systems that can be solved efficiently, we introduce a time splitting method. The resulting linear systems are solved iteratively by using the preconditioned Conjugate Gradients Squared method.

ISSN:0029-5981    

DOI:10.1002/nme.1620261209

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this paper, the stiffness matrix of a contact element is introduced by means of a penalty function expression of the contact pressure and frictional force. The contact condition and the flow rule are expressed by the same form as in a non‐associated plastic flow problem. A unified PQP (Parametric Quadratic Programming) model related to contact problems as well as to elasto‐plastic structures is constructed. A series of PQP formulae for contact problems and elastic‐plastic structures is derived in the text, and some numerical examples are illustrated as

ISSN:0029-5981    

DOI:10.1002/nme.1620261210

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractGeneral two‐dimensional linear elastic fracture problems are investigated using the boundary element method. The √rdisplacement and 1/√rtraction behaviour near a crack tip are incorporated in special crack elements. Stress intensity factors of both modes I and II are obtained directly from crack‐tip nodal values for a variety of crack problems, including straight and curved cracks in finite and infinite bodies. A multidomain approach is adopted to treat cracks in an infinite body. The body is subdivided into two regions: an infinite part with a finite hole and a finite inclusion. Numerical results, compared with exact solution whenever possible, are accurate even with a coarse discret

ISSN:0029-5981    

DOI:10.1002/nme.1620261211

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY