Xiaoping Zhang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.2, pp. 35-36, 2011, DOI:10.3970/icces.2011.018.035

Abstract In this paper, we first discuss the midpoint rule for evaluating hypersingular integrals with the kernel \qopname \relax osin-2(x-s)/2 defined on a circle, and the key point is placed on its pointwise superconvergence phenomenon. We show that this phenomenon occurs when the singular point s is located at the midpoint of each subinterval and obtain the corresponding supercovergence analysis. Then we apply the rule to construct a collocation scheme for solving the relevant hypersingular integral equation, by choosing the midpoints as the collocation points. It's interesting that the inverse of coefficient matrix for the resulting More >

Dan Ma^1,2, Xianbiao Mao¹, Xiexing Miao¹, Shaojie Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.3&4, pp. 233-246, 2011, DOI:10.3970/cmes.2011.074.233

Abstract Rock surrounding the circular roadway with uniform and local support is one of the most common phenomenons in roadway support engineering, which needs to be studied thoroughly at the theoretical level. The existing literatures on stress field function of rock surrounding the roadway is largely restricted to analytical solutions of stress for roadways with a uniform support or no support at all, the corresponding stress solution under conditions of local support has not been provided. Based on the mechanical models of uniform support and local support, the methods of the complex variable function and the… More >

Linjun Wang¹, Xu Han², Youxiang Xie³

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.3&4, pp. 179-194, 2011, DOI:10.32604/cmes.2011.082.179

Abstract In this paper, a new homotopy perturbation method (IHPM) is presented and suggested to solve an ill-posed problem of multi-source dynamic loads reconstruction. We propose a stable and reliable modification, and obtain a new regularization method, then employ it to find the exact solution for the multi-source dynamic load identification problem. Also, this present method only needs easy computations rather than successive integrations. Finally, the performances of two numerical examples are given. Comparisons are performed between the original homotopy perturbation method (HPM) and IHPM. The results verify that the present method is very simple and More >

Y.C. Shiah¹, C. L. Tan²

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.2, pp. 95-108, 2011, DOI:10.3970/cmes.2011.078.095

Abstract By differentiating the Green function of Ting and Lee (1997) for 3D general anisotropic elastotatics in a spherical coordinate system as an intermediate step, and then using the chain rule, derivatives of up to the second order of this fundamental solution are obtained in exact, explicit, algebraic forms. No tensors of order higher than two are present in these derivatives, thereby allowing these quantities to be numerically evaluated quite expeditiously. These derivatives are required for the computation of the internal point displacements and stresses via Somigliana's identity in BEM analysis. Some examples are presented to More >

P. Maghoul¹, B. Gatmiri^1,2, D. Duhamel¹

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.1, pp. 51-76, 2011, DOI:10.3970/cmes.2011.078.051

Abstract This paper aims at obtaining boundary integral formulations as well as three dimensional(3D) fundamental solutions for unsaturated soils under dynamic loadings for the first time. The boundary integral equations are derived via the use of the weighted residuals method in a way that permits an easy discretization and implementation in a Boundary Element code. Also, the associated 3D fundamental solutions for such deformable porous medium are derived in Laplace transform domain using the method of Hérmander. The derived results are verified analytically by comparison with the previously introduced corresponding fundamental solutions in elastodynamic limiting case. More >

L. Hedhili, A. Sellier, L. Elasmi, F. Feuillebois

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.2, pp. 137-170, 2011, DOI:10.3970/cmes.2011.073.137

Abstract The motion of a solid particle embedded in a viscous fluid in a closed container requires a precise account of wall effects when in creeping flow. The boundary integral method, which amounts to solving a Fredholm integral equation for the stress on the particle and walls, is used here. The accuracy of the method is improved by using curvilinear six-node triangular boundary elements, the size of which is specially adapted to the particle shape and position with respect to walls. The method is applied to resolve the case of a moving particle in a parallelepiped More >

Chih-Wen Chang¹

CMC-Computers, Materials & Continua, Vol.24, No.3, pp. 209-238, 2011, DOI:10.3970/cmc.2011.024.209

Abstract In this study, we employ a semi-analytical scheme to resolve the three-dimensional backward heat conduction problem (BHCP) by utilizing a quasi-bound -ary concept. First, the Fourier series expansion method is used to estimate the temperature field u(x, y, z, t) at any time t < T. Second, we ponder a direct regularization by adding an extra term a(x, y, z, 0) to transform a second-kind Fredholm integral equation for u(x, y, z, 0). The termwise separable property of the kernel function allows us to acquire a closed-form regularized solution. In addition, a tactic to determine More >

J. Sladek¹, V. Sladek¹, P. Stanak¹, E. Pan²

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.3, pp. 267-298, 2010, DOI:10.3970/cmes.2010.064.267

Abstract The plate equations are obtained by means of an appropriate expansion of the mechanical displacement and electric potential in powers of the thickness coordinate in the variational equation of electroelasticity and integration through the thickness. The appropriate assumptions are made to derive the uncoupled equations for the extensional and flexural motion. The present approach reduces the original 3-D plate problem to a 2-D problem, with all the unknown quantities being localized in the mid-plane of the plate. A meshless local Petrov-Galerkin (MLPG) method is then applied to solve the problem. Nodal points are randomly spread… More >

A. Aimi¹, M. Diligenti¹, S. Panizzi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.58, No.2, pp. 185-220, 2010, DOI:10.3970/cmes.2010.058.185

Abstract In this paper we consider 2D wave propagation Neumann exterior problems reformulated in terms of a hypersingular boundary integral equation with retarded potential. Starting from a natural energy identity satisfied by the solution of the differential problem, the related integral equation is set in a suitable space-time weak form. Then, a theoretical analysis of the introduced formulation is proposed, pointing out the novelties with respect to existing literature results. At last, various numerical simulations will be presented and discussed, showing accuracy and stability of the space-time Galerkin boundary element method applied to the energetic weak More >

V.V. Zozulya¹

CMES-Computer Modeling in Engineering & Sciences, Vol.70, No.3, pp. 253-350, 2010, DOI:10.3970/cmes.2010.070.253

Abstract In this article the divergent integrals, which arise when the boundary integral equation (BIE) methods are used for solution of the 3-D elastostatic problems is considered. The same approach for weakly singular, singular and hypersingular integral regularization is developed. The approach is based on theory of distribution and Green's theorems. This approach is applied for regularization of the divergent integrals over convex polygonal boundary elements (BE) in the case of piecewise constant approximation and over rectangular and triangular BE for piecewise linear approximation. The divergent integrals are transformed into the regular contour integrals that can More >