摘要:

AbstractA functional has been developed for the finite element solution of diffusion—convection problems. This functional is suitable for the application of the variational principle on discretization schemes in the space—time domain. This algorithm has shown to be computationally efficient over the conventional finite element discretization in the space domain alone. Numerical examples on one‐dimensional energy transport have been included to illustrate the merit of this tech

ISSN:0029-5981    

DOI:10.1002/nme.1620230502

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA method using techniques of computational geometry for triangular mesh generation for regions with complicated polygonal boundaries in the plane is presented. The input to the method includes the desired number of triangles and a mesh smoothness parameter to be specified, as well as the polygonal curves of the region's boundary and, possibly, internal interfaces. The triangulation generated conforms to the length scales of the edges of the boundary curves, but the method can be extended to provide additional control of the triangulation by a mesh distribution function. The region is decomposed into convex subregions in two stages, such that triangles of one length scale can be generated in each subregion. This decomposition uses algorithms which run in times that are linear in the number of vertices of the input polygons. Details of two major computational experiments are provided.

ISSN:0029-5981    

DOI:10.1002/nme.1620230503

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper is concerned with the numerical solution of large deflection structural problems involvingfinite strains, subject tocontactconstraints andunilateralboundary conditions, and exhibitinginelasticconstitutive response. First, a three‐dimensional finite strain beam model is summarized, and its numerical implementation in the two‐dimensional case is discussed. Next, a penalty formulation for the solution of contact problems is presented and the correct expression for consistent tangent matrix is developed. Finally, basic strategies for tracing limit points are reviewed and a modification of the arc‐length method is proposed. The good performance of the procedures discussed is illustrated by means of numerical exa

ISSN:0029-5981    

DOI:10.1002/nme.1620230504

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThis paper presents the implementation of an adaptive philosophy to plane potential problems, using the direct boundary element method. After some considerations about the state of the art and a discussion of the standard approach features, the possibility of separately treating the modelling of variables and their interpolation through hierarchical shape functions is analysed. Then the proposed indicators and estimators are given, followed by a description of a small computer program written for an IBM PC. Finally, some examples show the kind of results to be expected.

ISSN:0029-5981    

DOI:10.1002/nme.1620230505

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractAs an effort to predict effectively the actual collapse load of a structure, a series of numerical studies on the stability of shell structures are made. The difference in formulation between the two types of linear buckling loads, the classical and the fully linearized, is first demonstrated. Their correlations with respect to the actual stability limit of the structure are compared, and finally the two types of critical load approximations are obtained at various stages of a nonlinear analysis to study the pattern of convergence to the actual collapse load. It is found that the fully linearized buckling analysis, when combined with nonlinear analysis, can serve as a useful tool for prediction of the stability limit of a structure. While for most types of structures the approximation is within engineering accuracy, the rate of convergence of the extrapolated critical load also gives some insight to the accuracy of the approximation.

ISSN:0029-5981    

DOI:10.1002/nme.1620230506

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractMany current approaches to finite element modelling of large deformation elastic—plastic forming problems use a rate form of the virtual work (equilibrium) equations, and a finite element representation of the displacement components. Called the incremental method, this approach produces a three‐field formulation in which displacements, stresses and effective strain are dependent variables. Next, the formulation is converted to a one‐field displacement formulation by an algebraic time discretization which uses a low order explicit time‐stepping procedure to integrate the equations. This approach does not produce approximations which satisfy the discrete equilibrium equations at all times and, moreover, the advantage of the single‐field algebraic formulation is realized at the expense of very small time steps needed to produce stability and accuracy in the numerical calculations.This paper describes a variant of the mixed method in which all three field variables (displacements, stresses and effective strain) are given finite element representations. The discrete equilibrium equations then generate a nonlinear system of algebraic equations whose solutions represent a manifold, while the constitutive equations form a system of ordinary differential equations. A commercially available, variable time step/variable order code is then used to integrate this differential/algebraic system. When applied to the problem of hydrostatic bulging of a membrane, the new approach requires far less computer time than the increment

ISSN:0029-5981    

DOI:10.1002/nme.1620230507

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractFor plane stress/plane strain analysis, the 9‐node quadrilateral element performs better than the corresponding 8‐node element, especially for non‐rectangular shapes. For improved element flexibility and lower computer cost, 2 × 2 quadrature is generally preferable to 3 × 3 quadrature. Unfortunately the 9‐node element contains spurious zero‐energy modes when under‐integrated. A method is proposed to restrain these modes without significant loss of accuracy

ISSN:0029-5981    

DOI:10.1002/nme.1620230508

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractRotary inertia and dynamic‐correction rotary inertia matrices for a linearly tapered beam element of any cross‐sectional shape are derived in explicit form. Exact expressions for the required displacement functions are used in the derivation of these matrices. Variation of area and moment of inertia of the cross‐section along the axis of the element are exactly represented by simple functions involving shape factors. Vibration analysis results of a tapered cantilever beam of I‐section, obtained with and without the rotary inertia matrices are compared and effect of rotary inertia on vibration of tapered beams di

ISSN:0029-5981    

DOI:10.1002/nme.1620230509

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620230510

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe thermomechanical response of a uniaxial bar with thermoviscoplastic constitution is predicted herein using the finite element method. After a brief review of the governing field equations, variational principles are constructed for the one‐dimensional conservation of momentum and energy equations. These equations are coupled in that the temperature field affects the displacements and vice versa. Due to the differing physical nature of the temperature and displacements, first‐order and second‐order elements are utilized for these variables, respectively. The resulting semi‐discretized equations are then discretized in time using finite differencing. This is accomplished by Euler's method, which is utilized due to the stiff nature of the constitutive equations. The model is utilized in conjunction with stress‐strain relations developed by Bodner and Partom to predict the axial temperature field in a bar subjected to cyclic mechanical end displacements and temperature boundary conditions. It is found that spacial and time variation of the temperature field is significantly affected by the boundary conditions. The nomenclature used is given in an

ISSN:0029-5981    

DOI:10.1002/nme.1620230511

出版商:John Wiley&Sons, Ltd    

年代:1986

数据来源: WILEY