Sudib K. Mishra¹, J. K. Paik², S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.1, pp. 67-96, 2009, DOI:10.3970/cmes.2009.050.067

Abstract We present a simulation based study, by combining several models involving multiple time scales and physical processes, which govern the interfacial stress corrosion cracking (SCC) in grain boundaries, layered composites or bi-materials, and the mechanisms of inhibition using `smart' agents. The inhibiting agents described herein, automatically sense the initiation of damage, migrate to the sites and delay the corrosion kinetics involved in the process. The phenomenon of SCC is simulated using the lattice spring model (for the mechanical stresses), coupled with a finite difference model of diffusing species, causing the dissolution of the interfacial bonds. The dissolution is expressed through… More >

M.V. Menshykova¹, O.V. Menshykov, I.A. Guz

CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.2, pp. 107-120, 2009, DOI:10.3970/cmes.2009.048.107

Abstract The study is devoted to the problem for a linear crack located between two dissimilar elastic half-spaces under normally incident time-harmonic plane shear wave. The system of boundary integral equations for displacements and tractions is derived from the dynamic Somigliana identity. The distributions of the displacements and tractions at the bonding interface and the surface of the crack are analysed. The dynamic stress intensity factors (the opening and the transverse shear modes) are computed as functions of the frequency of the incident wave for different material properties. More >

J. Sladek¹, V. Sladek¹, P. Solek², C.L. Tan³, Ch. Zhang⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.47, No.1, pp. 61-96, 2009, DOI:10.3970/cmes.2009.047.061

Abstract The meshless local Petrov-Galerkin (MLPG) method for transient linear thermoelastic analysis is presented. Orthotropic material properties are considered here. In uncoupled thermoelasticity, the temperature field is not influenced by displacements. Therefore, in the first step, the heat conduction equation is solved for the temperature distribution in the domain. The equations of motion are then solved with the inertial term considered. A Heaviside step function as the test functions is applied in the weak-form to derive local integral equations for solving two- and three-dimensional problems. Local integral equations are written on small sub-domains with circular or spherical shapes. They surround nodal… More >

Yueting Zhou¹, Xing Li², Dehao Yu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.3, pp. 191-222, 2009, DOI:10.3970/cmes.2009.043.191

Abstract The transient response of an orthotropic functionally graded strip with a partially insulated crack under convective heat transfer supply is considered. It is modeled there exists thermal resistant in the heat conduction through the crack region. The mixed boundary value problems of the temperature field and displacement field are reduced to a system of singular integral equations in Laplace domain. The expressions with high order asymptotic terms for the singular integral kernel are considered to improve the accuracy and efficiency. The numerical results present the effect of the material nonhomogeneous parameters, the orthotropic parameters and dimensionless thermal resistant on the… More >

V.V. Zozulya¹

CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.3, pp. 187-216, 2009, DOI:10.3970/cmes.2009.042.187

Abstract The mathematical statement for contact problem with unilateral restrictions and friction is done in classical and weak forms. Different variational formulation of unilateral contact problems with friction based on principles of virtual displacements and virtual stresses are considered. Especially boundary variational functionals that are used with boundary integral equations have been established. Nonsmooth optimization algorithms of Udzawa type for solution of unilateral contact problem with friction have been developed. Some theoretical results of existence and uniqueness in elastostatic unilateral contact problem with friction are outlined. More >

M. Patrício¹, R. Mattheij¹, G. de With²

CMES-Computer Modeling in Engineering & Sciences, Vol.41, No.1, pp. 69-94, 2009, DOI:10.3970/cmes.2009.041.069

Abstract In this paper the effect of the local structure of a highly heterogeneous composite material on the parameters that characterise crack propagation is analysed. The evaluation of stress intensity factors is discussed. A hybrid approach based on domain decomposition and homogenisation methods is employed to obtain accurate solutions with reduced computational complexity. More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.40, No.1, pp. 1-28, 2009, DOI:10.3970/cmes.2009.040.001

Abstract We consider an inverse problem of Laplace equation by recoverning boundary value on the inner circle of a two-dimensional annulus from the overdetermined data on the outer circle. The numerical results can be used to determine the Robin coefficient or crack's position inside a disk from the measurements of Cauchy data on the outer boundary. The Fourier series is used to formulate the first kind Fredholm integral equation for the unknown data f(θ) on the inner circle. Then we consider a Lavrentiev regularization, by adding an extra term αf(θ) to obtain the second kind Fredholm integral equation. The termwise separable… More >

Raju Sethuraman¹, N.R.Rajesh²

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.1, pp. 67-100, 2009, DOI:10.3970/cmes.2009.039.067

Abstract This paper presents a methodology based on Partition of Unity Finite Element Method (PUFEM) and Pseudo Elastic Analysis for solving material non-linear fracture problems within the scope of total deformation theory of plasticity. Local enrichment base functions are used to represent the asymptotic field near the crack tip and discontinuous field across the crack faces. An iterative linear elastic analysis using PUFEM is carried out for the determination of elastic-plastic crack tip stress fields by treating effective material properties as spatial field variables. The effective material parameters are defined using deformation theory and are updated in an iterative manner based… More >

N. Sageresan, R. Drathi

CMES-Computer Modeling in Engineering & Sciences, Vol.32, No.2, pp. 103-112, 2008, DOI:10.3970/cmes.2008.032.103

Abstract Crack propagation in concrete is computed with a simplified meshless method. The material is elastic of Neo-Hookian type until fracture. Then a discrete cohesive crack method is used. In the cohesive crack method, cohesive segments are introduced at the meshless nodes. No representation of the crack surface is needed. The method is well-suited for concrete since concrete develops many cracks. Mesh independent results are obtained due to the cohesive model that takes into account the correct energy dissipation during crack opening. We show the accuracy of our method by comparison to experimental data. More >

Shishir Sinha¹, Praveen Ch.

CMES-Computer Modeling in Engineering & Sciences, Vol.32, No.2, pp. 85-102, 2008, DOI:10.3970/cmes.2008.032.085

Abstract Fluid catalytic cracking (FCC) unit plays most important role in the economy of a modern refinery that it is use for value addition to the refinery products. Because of the importance of FCC unit in refining, considerable effort has been done on the modeling of this unit for better understanding and improved productivity. The process is characterized by complex interactions among feed quality, catalyst properties, unit hardware parameters and process conditions. \newline The traditional and global approach of cracking kinetics is lumping. In the present paper, five lump kinetic scheme is considered, where gas oil crack to give lighter fractions… More >