B. Mochnacki¹, E. Majchrzak²

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 431-438, 2003, DOI:10.3970/cmes.2003.004.431

Abstract In the paper the analysis of transient temperature field in the domain of biological tissue subjected to an external heat source is presented. Because of the geometrical features of the skin the heat exchange in domain considered is assumed to be one-dimensional. The thermophysical parameters of successive skin layers (dermis, epidermis and sub-cutaneous region) are different, at the same time in sub-domains of dermis and sub-cutaneous region the internal heat sources resulting from blood perfusion are taken into account. The degree of the skin burn results from the value of the so-called Henriques integrals. The first and the second order… More >

P. Fedelinski¹, R. Gorski¹

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 31-40, 2006, DOI:10.3970/cmes.2006.015.031

Abstract The aim of the present work is to analyze and optimize plates in plane strain or stress with stiffeners subjected to dynamic loads. The reinforced structures are analyzed using the coupled boundary and finite element method. The plates are modeled using the dual reciprocity boundary element method (DR-BEM) and the stiffeners using the finite element method (FEM). The matrix equations of motion are formulated for the plate and stiffeners. The equations are coupled using conditions of compatibility of displacements and equilibrium of tractions along the interfaces between the plate and stiffeners. The final set of equations of motion is solved… More >

A. Milazzo¹, I. Benedetti², C. Orlando³

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 17-30, 2006, DOI:10.3970/cmes.2006.015.017

Abstract A boundary integral formulation and its numerical implementation are presented for the analysis of magneto electro elastic media. The problem is formulated by using a suitable set of generalized variables, namely the generalized displacements, which are comprised of mechanical displacements and electric and magnetic scalar potentials, and generalized tractions, that is mechanical tractions, electric displacement and magnetic induction. The governing boundary integral equation is obtained by generalizing the reciprocity theorem to the magneto electro elasticity. The fundamental solutions are calculated through a modified Lekhnitskii's approach, reformulated in terms of generalized magneto-electro-elastic displacements. To assess the reliability and effectiveness of the… More >

R. Springhetti¹, G. Novati¹, M. Margonari²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 67-80, 2006, DOI:10.3970/cmes.2006.013.067

Abstract With reference to potential and elastostatic problems, a BEM-FEM coupling procedure, based on the symmetric Galerkin version of the BEM, is developed; the continuity conditions at the interface of the BE and FE subdomains are enforced in weak form; the global linear system is characterized by a symmetric coefficient matrix. The procedure is numerically tested with reference first to 2D potential problems and successively to 3D elastoplastic problems (with plastic strains confined to the FE subdomain). More >

P.M. Baiz¹, M.H. Aliabadi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 19-34, 2006, DOI:10.3970/cmes.2006.013.019

Abstract In this paper the linear buckling problem of elastic shallow shells by a shear deformable shell theory is presented. The boundary domain integral equations are obtained by coupling two dimensional plane stress elasticity with boundary element formulation of Reissner plate bending. The buckling problem is formulated as a standard eigenvalue problem, in order to obtain directly critical loads and buckling modes as part of the solution. The boundary is discretised into quadratic isoparametric elements while in the domain quadratic quadrilateral cells are used. Several examples of cylindrical shallow shells (curved plates) with different dimensions and boundary conditions are analysed. The… More >

G.D. Hatzigeorgiou¹, D.E. Beskos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 791-802, 2002, DOI:10.3970/cmes.2002.003.791

Abstract This paper presents a general boundary element methodology for the dynamic analysis of three-dimensional inelastic solids and structures. Inelasticity is simulated with the aid of the continuum damage theory. The elastostatic fundamental solution is employed in the integral formulation of the problem and this creates in addition to the surface integrals, volume integrals due to inertia and inelasticity. Thus an interior discretization in addition to the usual surface discretization is necessary. Isoparametric linear quadrilateral elements are used for the surface discretization and isoparametric linear hexahedra for the interior discretization. Advanced numerical integration techniques for singular and nearly singular integrals are… 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 problem. More >

C. J. ZHENG, H. B. CHEN, T. MATSUMOTO, T. TAKAHASHI

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 121-122, 2011, DOI:10.3970/icces.2011.019.121

Abstract A fast multipole boundary element method is presented for three dimensional acoustic shape sensitivity analysis in this study. The Burton-Miller formula which is a linear combination of the conventional boundary integral equation and the normal derivative boundary integral equation is adopted to conquer the fictitious eigenfrequency problem associated with the conventional boundary integral equation method in solving exterior acoustic problems. The continuous adjoint variable method is implemented in the sensitivity analysis and the concept of material derivative is used in the derivation. Constant elements are employed to discretize the boundary so that the hypersingular boundary integrals contained in the formulae… More >

Zai You YAN

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.3, pp. 77-78, 2011, DOI:10.3970/icces.2011.017.077

Abstract In the boundary element method, treatment of all the possible singular integrals is very important for the correctness and accuracy of the solutions. Generally, the directional derivative of a weakly singular integral is computed by an integral in the sense of Cauchy principle value if the directional derivative of the weakly singular integral kernel is strongly singular or in the sense of Hadamard finite part integral if the the directional derivative of the weakly singular integral kernel is hypersingular. We will try to discover how the strongly singular and hypersingular integrals are generated and propose a method to avoid the… More >

Zai You Yan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.46, No.1, pp. 1-20, 2009, DOI:10.3970/cmes.2009.046.001

Abstract It is well-known that the velocity potential and its first normal derivative on the structure surface can be easily found in the boundary element method for problems of potential flow. Based on an investigation in progress, the gradient of the normal derivative of the velocity potential will be very helpful in the treatment of the so-called hypersingular integral. Through a coordinate transformation, such gradient can be expressed by the combination of the first and the second normal derivatives of the velocity potential. Then one interesting problem is how to find the second normal derivative of the velocity potential through the… More >