共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper presents a double layer potential approach of elastodynamic BIE crack analysis. Our method regularizes the conventional strongly singular expressions for the traction of double layer potential into forms including integrable kernels and 0th, 1st and 2nd order derivatives of the double layer density. The manipulation is systematized by the use of the stress function representation of the differentiated double layer kernel functions. This regularization, together with the use of B-spline functions, is shown to provide accurate numerical methods of crack analysis in 3D time harmonic elastodynamics. 相似文献
2.
E. Becache 《International journal for numerical methods in engineering》1993,36(6):969-984
This paper investigates the transient wave scattering by a crack by means of the Boundary Integral Equation Method (BIEM). The author has developed a new formulation to solve the BIE for the Crack Opening Displacement (COD). The resolution is done directly in the time domain. The solution is represented by means of a retarded double layer potential, and the resulting BIE, with the COD as unknown, has a hypersingular kernel. The corresponding difficulty is overcome by using a variational method. We present the application of this method to an antiplane crack, describe the approximate problem and finally give some numerical results. 相似文献
3.
F. J. Rizzo D. J. Shippy 《International journal for numerical methods in engineering》1977,11(11):1753-1768
The features of an advanced numerical solution capability for boundary value problems of linear, homogeneous, isotropic, steady-state thermoelasticity theory are outlined. The influence on the stress field of thermal gradient, or comparable mechanical body force, is shown to depend on surface integrals only. Hence discretization for numerical purposes is confined to body surfaces. Several problems are solved, and verification of numerical procedures is obtained by comparison with accepted results from the literature. 相似文献
4.
Kuang‐Chong Wu 《中国工程学刊》2013,36(6):937-941
Abstract A novel integral equation method is developed in this paper for the analysis of two‐dimensional general anisotropic elastic bodies with cracks. In contrast to the conventional boundary integral methods based on reciprocal work theorem, the present method is derived from Stroh's formalism for anisotropic elasticity in conjunction with Cauchy's integral formula. The proposed boundary integral equations contain boundary displacement gradients and tractions on the non‐crack boundary and the dislocations on the crack lines. In cases where only the crack faces are subjected to tractions, the integrals on the non‐crack boundary are non‐singular. The boundary integral equations can be solved using Gaussian‐type integration formulas directly without dividing the boundary into discrete elements. Numerical examples of stress intensity factors are given to illustrate the effectiveness and accuracy of the present method. 相似文献
5.
《Engineering Analysis with Boundary Elements》2001,25(4-5):239-247
Fast multipole method (FMM) has been developed as a technique to reduce the computational cost and memory requirements in solving large scale problems. This paper discusses an application of the new version of FMM to three-dimensional boundary integral equation method (BIEM) for crack problems for the Laplace equation. The boundary integral equation is discretised with collocation method. The resulting algebraic equation is solved with generalised minimum residual method (GMRES). The numerical results show that the new version of FMM is more efficient than the original FMM. 相似文献
6.
N. Nishimura S. Kobayashi 《International journal for numerical methods in engineering》1991,32(7):1371-1387
This paper discusses an application of a boundary integral equation method (BIEM) to an inverse problem of determining the shape and the location of cracks by boundary measurements. Suppose that a given body contains an interior crack, the shape and the location of which are unknown. On the exterior boundary of this body one carries out measurements which are interpreted mathematically as prescribing Dirichlet data and measuring the corresponding Neumann data, or vice versa, for a field governed by Laplace's equation. The inverse problem considered here attempts to determine the geometry of the crack from these experimental data. We propose to solve this problem by minimizing the error of a certain boundary integral equation (BIE). The process of this minimization, however, is shown to require solutions of certain are proposed. Several 2D and 3D numerical examples are given in order to test the performance of the present method. 相似文献
7.
《Engineering Analysis with Boundary Elements》1999,23(1):97-105
This paper discusses a three-dimensional fast multipole boundary integral equation method for crack problems for Laplace's equation. The proposed implementation uses collocation and piecewise constant shape functions to discretise the hypersingular boundary integral equation for crack problems. The resulting numerical equation is solved with GMRES (generalised minimum residual method) in connection with FMM (fast multipole method). It is found that the obtained code is faster than a conventional one when the number of unknowns is greater than about 1300. 相似文献
8.
Yin-Bang Wang 《Engineering Fracture Mechanics》2005,72(13):2128-2143
By using integration by parts to the traditional boundary integral formulation, a traction boundary integral equation for cracked 2-D anisotropic bodies is derived. The new traction integral equation involves only singularity of order 1/r and no hypersingular term appears. The dislocation densities on the crack surface are introduced and the relations between stress intensity factors and dislocation densities near the crack tip are induced to calculate the stress intensity factors. The boundary element method based on the new equation is established and the singular interpolation functions are introduced to model the singularity of the dislocation density (in the order of ) for crack tip elements. The proposed method can be directly used for the 2-D anisotropic body containing cracks of arbitrary geometric shapes. Several numerical examples demonstrate the validity and accuracy of BEM based on the new boundary integral equation. 相似文献
9.
Guizhong Xie Jianming Zhang Cheng Huang Chenjun Lu Guangyao Li 《Computational Mechanics》2014,53(4):575-586
This paper presents a direct traction boundary integral equation method (TBIEM) for three-dimensional crack problems. The TBIEM is based on the traction boundary integral equation (TBIE). The TBIE is collocated on both the external boundary and one of the crack surfaces. The displacements and tractions are used as unknowns on the external boundary and the relative crack opening displacements (CODs) are introduced as unknowns on the crack surface. In our implementation, all the surfaces of the considered structure are discretized into discontinuous elements to satisfy the continuity requirement for the existence of finite-part integrals, and special crack-front elements are constructed to capture the crack-tip behavior. To calculate the finite-part integrals, an adaptive singular integral technique is proposed. The stress intensity factors (SIFs) are computed through a modified COD extrapolation method. Numerical examples of SIFs computation are presented to demonstrate the accuracy and efficiency of our method. 相似文献
10.
A multi-domain boundary integral equation method, employing an isoparametric quadratic representation of geometries and functions, is developed for the analysis of two-dimensional linear elastic fracture mechanics problems. The multi-domain approach allows the two faces of a crack to be modelled in independent sub-regions of the body, avoiding singularity difficulties and making it possible to analyse crack closure problems with contact stresses over part of the cracked faces. Problems solved include slanted cracked plate mixed mode and crack closure examples, also crack closure situations involving fully reversed bending of an edge cracked strip, both with and without a superimposed tensile loading.
Résumé Pour analyser les problèmes de mécanique de rupture linéaire et élastique en deux dimensions, on a développé une formulation sur plusieurs domaines de la méthode d'équation intégrale aux limites, en recourant à une représentation quadratique isoparamétrique des géométries et des fonctions.L'approche multidomaine permet de modéliser les deux faces d'une fissure dans des sous-régions indépendantes, ce qui évite des difficultés de singularité, et rend possible l'analyse des problèmes de fermeture d'une fissure avec des contraintes de contact agissant sur une partie des faces de la fissure.Les problèmes auxquels on trouve solution sont notamment la plaque fissurée sur un bord et sollicitée suivant un mode mixte, avec aussi fermeture de la fissure, ou des situations de fermeture de fissure où se trouve une bande fissurée sur un de ses bords et soumise à flexion complète réversible, avec ou sans sollicitations de traction相似文献
11.
The paper describes a hybrid experimental-numerical technique for elastoplastic crack analysis. It consists of the experimental surface spectrum measurement of plastic strains ahead the crack tip and the boundary element method (BEM). The light scattering method is used to measure the power density spectrum from which the values of plastic strains are obtained by comparison with a calibration experiment on the same material. Plastic strains obtained experimentally are conveniently used for the calculation of unknown boundary displacement or traction vectors by the boundary element method. Instead of an iterative solution of the boundary integral equations in pure numerical solution, the boundary unknowns are computed once for a required loading level. Also asymptotic distribution of strains or stresses is not needed in the evaluation of the domain integral for the BEM formulation in the vicinity of the crack tip. Significant CPU time saving is achieved in comparison with the pure BEM solution. The method presented is illustrated by the example for a three point bending specimen with an edge crack. 相似文献
12.
R. T. Fenner J. O. Watson 《International journal for numerical methods in engineering》1988,26(11):2517-2529
Boundary integral equation (boundary element) methods have the advantage over other commonly used numerical methods that they do not require values of the unknowns at points within the solution domain to be computed. Further benefits would be obtained if attention could be confined to information at one small part of the boundary, the particular region of interest in a given problem. A local boundary integral equation method based on a Taylor series expansion of the unknown function is developed to do this for two-dimensional potential problems governed by Laplace's equation. Very accurate local values of the function and its derivatives can be obtained. The method should find particular application in the efficient refinement of approximate solutions obtained by other numerical techniques. 相似文献
13.
A new boundary integral method for plane elasticity problems with internal piece-wise smooth cracks is presented. The method can be applied to both infinite and finite geometries. A numerical technique which combines a collocation method for the cracks and the standard BEM technique for the outer boundary is used to solve the integral equations. Numerical examples are presented and compared either to existing solutions or to FEM calculations. All of the results provided by the present method are shown to be very accurate for both smooth and kinked cracks in both finite and infinite geometries.
Résumé On présente une nouvelle méthode par intégrale de contour pour solutionner des problèmes d'élasticité plane de géométries comportant des fissures lisses similaires à des pièces. Cette méthode est applicable à des géométries infinies ou finies. Pour solutionner les équations intégrales, on utilise une technique numérique combinant une méthode de collocation pour les fissures, et la technique standard BEM pour les limites extérieures. On compare les exemples numériques et on les compare aux solutions existantes ou aux résultats de calculs par éléments finis. On montre que les résultats présentés par la présente méthode sont très précis pour des fissures lisses ou tourmentées, dans des géométries finies ou infinies.相似文献
14.
《Engineering Analysis with Boundary Elements》2003,27(4):291-304
Time-domain analysis of electromagnetic wave fields is popularly performed by the Finite Difference Time-Domain method. Then the Boundary Integral Equation Method (BEM) still has advantage comparing with FDM or FEM type scheme in open boundary problems, moving boundary problems and coupled problems of charge particle and electromagnetic fields. However, the time-domain boundary integral equation method still do not well developed, numerical instability in long time range calculations frequently appear except for special cases. In this paper, a stable scheme of the time-domain boundary integral equation method is presented and numerical example of particle accelerator wake fields is shown. 相似文献
15.
《Engineering Analysis with Boundary Elements》2005,29(4):334-342
This paper presents a meshless local boundary integral equation method (LBIEM) for dynamic analysis of an anti-plane crack in functionally graded materials (FGMs). Local boundary integral equations (LBIEs) are formulated in the Laplace-transform domain. The static fundamental solution for homogeneous elastic solids is used to derive the local boundary–domain integral equations, which are applied to small sub-domains covering the analyzed domain. For the sub-domains a circular shape is chosen, and their centers, the nodal points, correspond to the collocation points. The local boundary–domain integral equations are solved numerically in the Laplace-transform domain by a meshless method based on the moving least–squares (MLS) scheme. Time-domain solutions are obtained by using the Stehfest's inversion algorithm. Numerical examples are given to show the accuracy of the proposed meshless LBIEM. 相似文献
16.
The authors present a new method to compute the current distribution at the surface of a conducting piece in a high frequency varying field. This method uses boundary integral equation techniques and allows at a very low computing cost to define in three dimensions the hot and cold parts of such a piece before case hardening. The integral equations have to be solved only on the boundary, so the number of dimensions of the mathematical problem is reduced from three to two. Results of current distribution on the surface of a complicated shape piece as a toothed gear are given as an example. 相似文献
17.
R. Kress 《Journal of Engineering Mathematics》1981,15(1):29-48
Summary A Neumann boundary value problem for the equation rot –=0 is considered in 29-1 and 29-2. The approach is by transforming the boundary value problem into an equivalent boundary integral equation deduced from a representation formula for solutions of rot –=0 based on the fundamental solution of the Helmholtz equation. In particular, for the two-dimensional case a detailed discussion of the integral equation is carried out including the approximate solution by numerical integration. 相似文献
18.
In this paper the notch problem of antiplane elasticity is discussed and a new boundary integral equation is formulated. In the problem, the distributed dislocation density is taken to be the unknown function. Unlike the usual choice, the resultant force function is taken as the right hand term of the integral equation; therefore, a new boundary integral equation for the notch problem of antiplane elasticity with a weaker singular kernel (logarithmic) is obtained. After introducing a particular fundamental solution of antiplane elasticity, the notch problem for the half-plane is discussed and the relevant boundary integral equation is formulated. The integral equations derived are compact in form and convenient for computation. Numerical examples demonstrated that high accuracy can be achieved by using the new boundary equation. 相似文献
19.
A new boundary integral equation for the notch problem of plane elasticity is formulated in this paper. In the formulation, the distributed dislocation density is taken to be the unknown function and the resultant force function to be the right-hand term in the resulting integral equation. As a result the integral equation derived contains a logarithmic kernel. The equation is compact in form and convenient for computation. The accuracy of the method is demonstrated through a number of numerical examples. 相似文献
20.
Ken‐ichi Yoshida Naoshi Nishimura Shoichi Kobayashi 《International journal for numerical methods in engineering》2001,50(3):525-547
Fast multipole method (FMM) has been developed as a technique to reduce the computational cost and memory requirements in solving large‐scale problems. This paper discusses an application of FMM to three‐dimensional boundary integral equation method for elastostatic crack problems. The boundary integral equation for many crack problems is discretized with FMM and Galerkin's method. The resulting algebraic equation is solved with generalized minimum residual method (GMRES). The numerical results show that FMM is more efficient than conventional methods when the number of unknowns is more than about 1200 and, therefore, can be useful in large‐scale analyses of fracture mechanics. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献