Yoshihiro Ochiai¹, Vladimir Sladek²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.6, pp. 525-536, 2004, DOI:10.3970/cmes.2004.006.525

Abstract The conventional boundary element method (BEM) uses internal cells for the domain integralsCwhen solving nonlinear problems or problems with domain effects. This paper is concerned with conversion of the domain integral into boundary ones and some non-integral terms in a three-dimensional BIEM, which does not require the use of internal cells. This method uses arbitrary internal points instead of internal cells. The method is based on a three-dimensional interpolation method in this paper by using a polyharmonic function with volume distribution. In view of this interpolation method, the three-dimensional numerical integration is replaced by boundary More >

S. N. Atluri¹, Z. D. Han¹, A. M. Rajendran²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.6, pp. 491-514, 2004, DOI:10.3970/cmes.2004.006.491

Abstract The Meshless Finite Volume Method (MFVM) is developed for solving elasto-static problems, through a new Meshless Local Petrov-Galerkin (MLPG) ``Mixed'' approach. In this MLPG mixed approach, both the strains as well as displacements are interpolated, at randomly distributed points in the domain, through local meshless interpolation schemes such as the moving least squares(MLS) or radial basis functions(RBF). The nodal values of strains are expressed in terms of the independently interpolated nodal values of displacements, by simply enforcing the strain-displacement relationships directly by collocation at the nodal points. The MLPG local weak form is then written… More >

Z. D. Han¹, S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.2, pp. 169-188, 2004, DOI:10.3970/cmes.2004.006.169

Abstract Three different truly Meshless Local Petrov-Galerkin (MLPG) methods are developed for solving 3D elasto-static problems. Using the general MLPG concept, these methods are derived through the local weak forms of the equilibrium equations, by using different test functions, namely, the Heaviside function, the Dirac delta function, and the fundamental solutions. The one with the use of the fundamental solutions is based on the local unsymmetric weak form (LUSWF), which is equivalent to the local boundary integral equations (LBIE) of the elasto-statics. Simple formulations are derived for the LBIEs in which only weakly-singular integrals are included More >

P. Raghavan¹, S. Ghosh²

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 151-170, 2004, DOI:10.3970/cmes.2004.005.151

Abstract This paper presents an adaptive multi-level computational model that combines a conventional displacement based finite element model with a microstructural Voronoi cell finite element model for multi-scale analysis of composite structures with non-uniform microstructural heterogeneities as obtained from optical or scanning electron micrographs. Three levels of hierarchy, with different resolutions, are introduced in this model to overcome shortcomings posed by modeling and discretization errors. Among the three levels are: (a) level-0 of pure macroscopic analysis; (b) level-1 of macro-micro coupled modeling, used for signaling the switch over from macroscopic analyses to pure microscopic analyses; and More >

Hiroshi Okada¹, Yasuyoshi Fukui¹, Noriyoshi Kumazawa¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 135-150, 2004, DOI:10.3970/cmes.2004.005.135

Abstract A method to obtain the effective mechanical properties of particulate composite materials is presented in this paper. The methodology is based on the boundary element method (BEM) coupled with analytical solutions for ellipsoidal inclusions such as Eshelby's tensor. There is no numerical integration for the surfaces or the domains of distributed particles, and, therefore, proposed technique is very efficient. Homogenization analysis based on representative volume element (RVE) is carried out considering a unit cell containing many particles (up to 1000). By using a conventional BEM approach (i.e., multi-region BEM), it would be extremely difficult to More >

Spandan Maiti¹, Philippe H. Geubelle¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 91-102, 2004, DOI:10.3970/cmes.2004.005.091

Abstract The dynamic propagation and branching of a mode I crack in polycrystalline brittle materials like ceramics are investigated numerically using a 2-D explicit grain-based cohesive/volumetric finite element scheme. The granular microstructure of the ceramics is taken into account and the crack is restricted to propagate along the grain boundaries. Special emphasis is placed on studying the effect of grain size and cohesive parameters on the crack branching instability. More >

N. Chandra¹ and C. Shet

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 21-34, 2004, DOI:10.3970/cmes.2004.005.021

Abstract Cohesive Zone Models (CZMs)\ are increasingly being used to simulate fracture and fragmentation processes in metallic, polymeric, ceramic materials and composites thereof. Instead of an infinitely sharp crack envisaged in linear elastic fracture mechanics, CZM assumes the presence of a fracture process zone where the energy is transferred from external work both in the forward and the wake regions of the propagating crack. In this paper, some of the mechanistic and computational issues in the application of CZM \ to model failure and fracture in real materials are discussed. In specific we address the issue More >

H.J. Bohm¨ ¹, W. Han^1,2, A. Eckschlager^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 5-20, 2004, DOI:10.3970/cmes.2004.005.005

Abstract Three-dimensional periodic micromechanical models are used for studying the mechanical behavior of discontinuously reinforced ductile matrix composites. The models are based on unit cells that contain a number of randomly positioned and, where applicable, randomly oriented spherical, spheroidal or cylindrical reinforcements. The Finite Element method is used to resolve the microscale stress and strain fields and to predict the homogenized responses under overall uniaxial tensile loading in the elastic and elastoplastic regimes. Periodicity boundary conditions are employed in the analyses.\\ The main emphasis of the contribution is put on studying the microscale stresses in the More >

Chih-Ping Wu¹, Yen-Wei Chi¹

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 337-352, 2004, DOI:10.3970/cmc.2004.001.337

Abstract Within the framework of the three-dimensional (3D) nonlinear elasticity, a refined asymptotic theory is developed for the nonlinear analysis of laminated circular cylindrical shells. In the present formulation, the basic equations including the nonlinear relations between the finite strains (Green strains) and displacements, the nonlinear equilibrium equations in terms of the Kirchhoff stress components and the generalized Hooke's law for a monoclinic elastic material are considered. After using proper nondimensionalization, asymptotic expansion, successive integration and then bringing the effects of transverse shear deformation into the leading-order level, we obtain recursive sets of the governing equations… More >

A. Rama Chandra Murthy¹, G.S. Palani¹, Nagesh R. Iyer¹

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 289-300, 2004, DOI:10.3970/cmc.2004.001.289

Abstract In this paper an improved Wheeler residual stress model has been proposed for remaining life assessment of cracked plate panels under variable amplitude loading (VAL). The improvement to the Wheeler residual stress model is in terms of the expressions for the shaping exponent, which is generally obtained through experiments. Simple expressions for the computation of shaping exponent have been proposed for compact tension (CT) specimen and plate panels with a center crack or an edge crack. The remaining life assessment has been carried out by employing linear elastic fracture mechanics (LEFM) principles. In the present… More >