H.M. Lee¹, H.S. Park^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.1, pp. 29-44, 2008, DOI:10.3970/cmes.2008.029.029

Abstract This paper presents a computational model to estimate deformed shapes of beam structures using 3D coordinate information from terrestrial laser scanning (TLS). The model is composed of five components: 1) formulation of polynomial shape function, 2) application of boundary condition, 3) inducement of compatibility condition, 4) application of the least square method and 5) evaluation of error vector and determination of reasonable polynomial shape function. In the proposed model, the optimal degree of polynomial function is selected based on the complexity of beam structures, instead of using a specific degree of polynomial function. The chosen More >

V.C. Mariani¹, E.E.M. Alonso², S. Peters³

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.1, pp. 15-28, 2008, DOI:10.3970/cmes.2008.029.015

Abstract An application of Newton's method for linearization of advective terms given by the discretization on unstructured Voronoi meshes for the incompressible Navier-Stokes equations is proposed and evaluated in this article. One of the major advantages of the unstructured approach is its application to very complex geometrical domains and the mesh is adaptable to features of the flow. Moreover, in this work comparisons with the literature results in bi-dimensional lid-driven cavities for different Reynolds numbers allow us to assess the numerical properties of the new proposed finite-volume scheme. Results for the components of the velocity, and More >

H. T. Wang¹, Z. H. Yao²

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.1, pp. 1-14, 2008, DOI:10.3970/cmes.2008.029.001

Abstract Carbon nanotubes (CNTs) may provide ultimate enhancement in stiffness and strength for composite materials. This paper presents a rigid-fiber-based boundary integral equation formulation for the numerical simulation of debonding process and the corresponding strength of CNT reinforced composites. The CNT/matrix interfaces are assumed to fail when the interfacial shear force reaches a prescribed threshold, and the CNTs and matrix are considered to be detached in the failed areas. The matrix with one or several tens of originally well-bonded CNTs is subjected to an incremental tensile load and the effective stress-strain relations are readily obtained by… More >

S.Y. Long^1,2,3, K.Y. Liu^1,2,4, G.Y. Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 203-216, 2008, DOI:10.3970/cmes.2008.028.203

Abstract A meshless local Petrov-Galerkin method (MLPG) for the analysis of the elasto-plastic fracture problem is presented in this paper. The meshless method uses the moving least squares (MLS) to approximate the field functions. The shape function has not Kronecker Delta properties for the trial-function interpolation, and a direct interpolation method is adopted to impose essential boundary conditions. The MLPG method does not involve any domain and singular integrals if body force is ignored. It only involves a regular boundary integral. Two numerical examples show that results obtained by the present method have a good agreement More >

D. Kourounis¹, L.N. Gergidis¹, A. Charalambopoulos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 185-202, 2008, DOI:10.3970/cmes.2008.028.185

Abstract The sensitivity of analytical solutions of the direct acoustic scattering problem in prolate spheroidal geometry on the wavenumber and shape, is extensively investigated in this work. Using the well known Vekua transformation and the complete set of radiating "outwards'' eigensolutions of the Helmholtz equation, introduced in our previous work ([Charalambopoulos and Dassios(2002)], [Gergidis, Kourounis, Mavratzas, and Charalambopoulos (2007)]), the scattered field is expanded in terms of it, detouring so the standard spheroidal wave functions along with their inherent numerical deficiencies. An approach is employed for the determination of the expansion coefficients, which is optimal in… More >

S S Panda¹, C S Manohar^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 161-184, 2008, DOI:10.3970/cmes.2008.028.161

Abstract The problem of reliability analysis of randomly parametered, linear (or) nonlinear, structures subjected to static and (or) dynamic loads is considered. A deterministic finite element model for the structure to analyze sample realization of the structure is assumed to be available. The reliability analysis is carried out within the framework of response surface methods which involves the construction of surrogate models for performance functions to be employed in reliability calculations. This construction, in the present study, has involved combining space filling optimal Latin hypercube sampling, kriging models and methods from data-based asymptotic extreme value modeling More >

N.Kringos¹, A.Scarpas¹, A.P.S. Selvadurai²

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 147-160, 2008, DOI:10.3970/cmes.2008.028.147

Abstract This paper presents a numerical approach for the modeling of water flow induced mastic erosion from a permeable asphalt mix and is part of an ongoing effort to model moisture-induced damage in asphalt mixes. Due to the complex composite structure of asphalt mixtures, moisture can infiltrate in various ways into the components and have an adverse effect on its mechanical performance. Depending on the gradation of the asphalt aggregates and the mixing procedure, asphalt structures with a variable permeability may result. Open-graded asphalt mixes are designed with a high interconnected air void content to serve More >

Atsuya Oishi¹, Shinobu Yoshimura²

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.2, pp. 127-146, 2008, DOI:10.3970/cmes.2008.028.127

Abstract This paper describes new methods based on genetic approaches for finding approximating expressions of local coordinates of a contact point in a local contact search process. A contact search process generally consists of the following two phases: a global search phase for finding the nearest node-segment pair and a local search phase for finding an exact local coordinate of the contact point within the segment. The local contact search can be regarded as the mapping from the coordinates of nodes to the local coordinates of contact points. In this paper, two methods are proposed to… More >

X.Y. Cui^1,2, G. R. Liu^2,3, G. Y. Li¹, X. Zhao², T.T. Nguyen², G.Y. Sun¹

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.2, pp. 109-126, 2008, DOI:10.3970/cmes.2008.028.109

Abstract A smoothed finite element method (SFEM) is presented to analyze linear and geometrically nonlinear problems of plates and shells using bilinear quadrilateral elements. The formulation is based on the first order shear deformation theory. In the present SFEM, the elements are further divided into smoothing cells to perform strain smoothing operation, and the strain energy in each smoothing cell is expressed as an explicit form of the smoothed strain. The effect of the number of divisions of smoothing cells in elements is investigated in detail. It is found that using three smoothing cells for bending More >

Chun Yang¹, Dalin Tang², Chun Yuan³, William Kerwin², Fei Liu³, Gador Canton³, Thomas S. Hatsukami^3,4, Satya Atluri⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.2, pp. 95-108, 2008, DOI:10.3970/cmes.2008.028.095

Abstract Atherosclerotic plaque rupture and progression have been the focus of intensive investigations in recent years. Plaque rupture is closely related to most severe cardiovascular syndromes such as heart attack and stroke. A computational procedure based on meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Participating patients were scanned three times (T₁,T₂, and T₃, at intervals of about 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes were used as the measure for plaque progression.… More >