A. P. S. Selvadurai¹, Q. Yu²

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.1, pp. 85-110, 2005, DOI:10.3970/cmes.2005.009.085

Abstract A characteristic feature of a polymeric material such as PVC is its hyperelasticity or the ability to experience large strains prior to failure. The exposure of PVC to chemicals such as acetone and ethanol results in embrittlement or the loss of the hyperelasticity property. In this paper, we examine the mechanical behaviour of a PVC membrane that has been exposed to ethanol. Due to leaching of the plasticizer, the constitutive response of the PVC changes from a hyperelastic material to a hardened material that displays dominant yield behaviour and particularly one that is capable of experiencing post-yield large strains and… More >

X. Liu, A. Scarpas¹

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.1, pp. 57-74, 2005, DOI:10.3970/cmes.2005.009.057

Abstract Numerical investigations of strain localization have been performed on 3D dense fully saturated sand specimens subjected to triaxial loading and simultaneous inflow or outflow conditions. The role of the water suction field on the formation and evolution of strain localization is addressed computationally. It has been shown that, in a porous medium, the fluid (water) phase plays indeed an important role in strain localization. The formation and evolution of strain localization are influenced both by the material behaviour of the solid component and the interaction between components. In this contribution, after a presentation of the incremental formulation of the coupled… More >

W. J. Ferguson¹, B. Palananthakumar²

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 201-216, 2005, DOI:10.3970/cmes.2005.008.201

Abstract Environmental and safety issues associated with landfill gas require the control of off-site migration. Mathematical modelling can assist in the understanding of the processes and mechanisms controlling gas migration from municipal waste disposal sites. This paper presents the development and application of a mathematical model that simulates landfill gas migration within a partially saturated soil. This model accounts for two-phase flow and incorporates multi-component (methane, carbon dioxide, dry air and moisture) transport in the gas and liquid phases together with concomitant heat migration. The governing system of fully coupled non-linear partial differential equations of the model have been derived from… More >

C.W. Chen¹, C.M. Fan¹, D.L. Young^1,2, K. Murugesan¹, C.C Tsai³

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 29-44, 2005, DOI:10.3970/cmes.2005.008.029

Abstract We use a meshless numerical method to analyze the eigenanalysis of thin circular membranes with degenerate boundary conditions, composed by different orientations and structures of stringers. The membrane eigenproblem is studied by solving the two-dimensional Helmholtz equation utilizing the method of fundamental solutions and domain decomposition technique as well. The method of singular value decomposition is adopted to obtain eigenvalues and eigenvectors of the resulting system of global linear equation. The proposed novel numerical scheme was first validated by three circular membranes which are structured with a single edge stringer, two opposite edge stringers and an internal stringer. Present results… More >

Y.C. Shiah¹, T.L. Guao¹, C.L. Tan²

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.3, pp. 321-338, 2005, DOI:10.3970/cmes.2005.007.321

Abstract It is well known in elastic stress analysis using the boundary element method (BEM) that an additional volume integral appears in the basic form of the boundary integral equation if thermal effects are considered. In order to restore this general numerical tool as a truly boundary solution technique, it is perhaps most desirable to transform this volume integral exactly into boundary ones. For general 2D anisotropic thermo-elastostatics without heat sources, this was only achieved very recently. The presence of concentrated heat sources in the domain, however, leads to singularities at these points that pose additional difficulties in the volume-to-surface integral… More >

S. N. Atluri¹, Shengping Shen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.3, pp. 241-268, 2005, DOI:10.3970/cmes.2005.007.241

Abstract Various MLPG methods, with the MLS approximation for the trial function, in the solution of a 4$^{th}$ order ordinary differential equation are illustrated. Both the primal MLPG methods and the mixed MLPG methods are used. All the possible local weak forms for a 4$^{th}$ order ordinary differential equation are presented. In the first kind of mixed MLPG methods, both the displacement and its second derivative are interpolated independently through the MLS interpolation scheme. In the second kind of mixed MLPG methods, the displacement, its first derivative, second derivative and third derivative are interpolated independently through the MLS interpolation scheme. The… More >

C. Shu^1,2, H. Ding², K.S. Yeo²

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.2, pp. 195-206, 2005, DOI:10.3970/cmes.2005.007.195

Abstract Local radial basis function-based differential quadrature (RBF-DQ) method was recently proposed by us. The method is a natural mesh-free approach. It can be regarded as a combination of the conventional differential quadrature (DQ) method with the radial basis functions (RBFs) by means of taking the RBFs as the trial functions in the DQ scheme. With the computed weighting coefficients, the method works in a very similar fashion as conventional finite difference schemes. In this paper, we mainly concentrate on the applications of the method to incompressible flows in the steady and unsteady regions. The multiquadric (MQ) radial basis functions are… More >

Wanlin Guo^1,2, Huajian Gao²

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 19-34, 2005, DOI:10.3970/cmes.2005.007.019

Abstract A systematic investigation is performed on energy dissipation related interaction force associated with interlayer motion of sliding, rotation and telescoping between any two possible neighboring carbon nanotubes. In particular, we analyze the interlayer corrugation energy and sliding, rotation and telescoping resistance force associated with the Lennard-Jones potential as well as a registry-dependent graphitic potential. It is found that the interlayer resistance associated with both of these potentials can vary with the morphology, length and diameter of the two tubes. Energy dissipation related fluctuation of the resistant force can be as low as 10^-18N/atom between the most optimistic tube pairs, but… More >

De Xie¹, Anthony M. Waas^1,2, Khaled W. Shahwan³, Jessica A. Schroeder⁴, Raymond G. Boeman⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.6, pp. 515-524, 2004, DOI:10.3970/cmes.2004.006.515

Abstract A numerical method based on the virtual crack closure technique (VCCT) [Rybicki and Kanninen (1977)] and in conjunction with the finite element (FE) method is presented to compute strain energy release rates for cracks that kink. The method partitions the strain energy release rate and provides an efficient means to compute values of the mode I (G_I) and mode II (G_II) energy release rate at the tip of a kinking crack. The solution procedure is shown to be computationally efficient and operationally simple, involving only the nodal forces and displacements near the crack tip. Example problems with kinking cracks in… More >

Alfredo Nicolás¹, Blanca Bermúdez²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.5, pp. 441-452, 2004, DOI:10.3970/cmes.2004.006.441

Abstract 2D incompressible vicous flows from the unsteady Navier-Stokes equations in stream function-vorticity variables are presented. The results are obtained using a simple numerical procedure based on a fixed point iterative process to solve the nonlinear elliptic system that results once a second order time discretization is performed. Flows on the unregularized unit driven cavity are reported up to Reynolds numbers Re=5000 to compare them with those reported by other authors and supposed to be correct. Various long time computations are presented for Re=10000 to see its evolution as time-dependent flow. Moreover, results are reported for Re=10000, Re=15000 and Re=20000 to… More >