摘要:

AbstractA numerical method, based on the multiregion concept in the boundary element method, is presented for modelling crack propagation. The advantage of the method is that the non‐linear iterations only involve interface degrees of freedom and that the propagation of cracks is modelled by disconnecting degrees of freedom and no remeshing is necessar

ISSN:0029-5981    

DOI:10.1002/nme.1620362102

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA finite‐element‐boundary‐element (FE‐BE) coupling method based on a weighted residual variational method is presented for potential problems, governed by either the Laplace or the Poisson equations. In this method, a portion of the domain of interest is modelled by finite elements (FE) and the remainder of the region by boundary elements (BE). Because the BE fundamental solutions are valid for infinite domains, a procedure that limits the effect of the BE fundamental solution to a small region adjacent to the FE region, called the transition region (TR), is developed. This procedure involves a judicious choice of functions called the transition (T) functions that have unit values on the BE‐TR interface and zero values on the FE‐TR interface. The present FE‐BE coupling algorithm is shown to be independent of the extent of the transition region and the choice of the transition functions. Therefore, transition regions that extend to only one layer of elements between FE and BE regions and the use of simple linear transition functi

ISSN:0029-5981    

DOI:10.1002/nme.1620362103

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe computational method for large deformation plasticity called differential equations on a manifold (DEM) has previously been shown to be effective for axisymmetric and plane strain sheet metal forming problems. The method has now been formulated for in‐plane stretching problems, incorporated into a computer code, and applied to several problems. The code's performance is robust and accurate, as evidenced by a comparison with other published results. Incorporation of an automatic mesh generator significantly reduces data preparation tim

ISSN:0029-5981    

DOI:10.1002/nme.1620362104

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA p‐version least‐squares finite element formulation for non‐linear problems is presented and applied to the steady‐state, one‐dimensional Burgers' equation. The second‐order equation is recast as a set of first‐order equations which permit the use of C0elements. The primary and auxiliary variables are approximated using equal‐order p‐version hierarchical approximation functions. The system of non‐linear simultaneous algebraic equations resulting from the least‐squares process is solved using Newton's method with a line search. The use of ‘exact’ and ‘reduced’ quadrature rules is investigated and the results are compared. The formulation is found to produce excellent results when the ‘exact’ integration rule is used. The combination of least‐squares finite element formulation and p‐version works extremely well for Burgers' equation and appears to have great

ISSN:0029-5981    

DOI:10.1002/nme.1620362105

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA three‐dimensional, geometrically non‐linear, two‐node Timoshenko beam element based on the total Lagrangian description is derived. The element behaviour is assumed to be linear elastic, but no restrictions are placed on the magnitude of finite rotations. The resulting element has twelve degrees of freedom: six translational components and six rotational‐vector components. The formulation uses the Green‐Lagrange strains and second Piola‐Kirchhoff stresses as energy‐conjugate variables and accounts for bending‐stretching and bending‐torsional‐coupling effects without special provisions. The core‐congruential formulation (CCF) is used to derive the discrete equations in a staged manner. Core equations involving the internal force vector and tangent stiffness matrix are developed at the particle level. A sequence of matrix transformations carries these equations to beam cross‐sections and finally to the element nodal degrees of freedom. The choice of finite rotation measure is made in the next‐to‐last transformation stage, and the choice of over‐the‐element interpolation in the last one. The tangent stiffness matrix is found to retain symmetry if the rotational vector is chosen to measure finite rotations. An extensive set of numerical examples are presented to test a

ISSN:0029-5981    

DOI:10.1002/nme.1620362106

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA finite element methodology for analysing propagating cracks of arbitrary three‐dimensional geometry is developed. By representing the opening displacements of the crack as a distribution of dislocation loops and minimizing the corresponding potential energy of the solid, the kernels of the governing integral equations have mild singularities of the type 1/R. A simple quadrature scheme then suffices to compute all the element arrays accurately. Because of the variational basis of the method, the resulting system of equations is symmetric. By employing six‐noded triangular elements and displacing midside nodes to quarter‐point positions, the opening profile near the front is endowed with the correct asymptotic behaviour. This enables the direct computation of stress intensity factors from the opening displacements. The special but important cases of periodic and semi‐infinite cracks are addressed in some detail. Finally, the geometry of propagating cracks is updated incrementally by recourse to a pseudodynamic crack‐tip equation of motion. The crack is continuously remeshed to accommodate the ensuing changes in geometry. The performance of the method is assessed by means of selected numerical

ISSN:0029-5981    

DOI:10.1002/nme.1620362107

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo‐dimensional elastoplastic problems are used to assess the performance of a family of mixed finite elements in the non‐linear regime. In particular, four‐node bilinear quadrilateral elements that exhibit high accuracy in coarse meshes are used to simulate plane stress, plane strain, axisymmetric and (shear‐deformable) plate bending problems. The excellent performance of these elements is demonstrated with a number of discriminating examples selected from the literature. In addition, agreement is observed in the limit load predicted by the axisymmetric solid and plate bending e

ISSN:0029-5981    

DOI:10.1002/nme.1620362108

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo mixed‐interpolated general shell finite elements for non‐linear analysis‐a 9‐node element and a 16‐node element‐are presented. The elements are based on the Mixed Interpolation of Tensorial Components (MITC) approach in which the covariant strain component fields for the in‐plane and shear actions are interpolated and tied to the also interpolated displacement field. Both the 9‐node element, referred to as the MITC9 element, and the 16‐node element, referred to as the MITC16 element, are tested numerically and found to have high predic

ISSN:0029-5981    

DOI:10.1002/nme.1620362109

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620362110

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0029-5981    

DOI:10.1002/nme.1620362101

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY