R. Ghelichi¹, S. Bagherifard¹, I. Fernandez Parienete², M.Guagliano^1,3, Simone Vezzù⁴

Structural Durability & Health Monitoring, Vol.6, No.1, pp. 17-30, 2010, DOI:10.3970/sdhm.2010.006.017

Abstract Coating deposition processes such as cold spraying are commonly employed to increase wear and fatigue resistance and consequently to enhance longevity of engineering components. Such processes typically introduce residual stresses into the coated surface, which in turn affect efficiency of coatings and play an important role in coating durability. In fact residual stresses are the key parameter to obtain compact and well-adherent coatings. They can modify several coating properties such as adhesion, structure, toughness, hardness reflecting on the macroscopic chemical and mechanical behavior of the coating.
Present study describes alteration of residual stress state of two More >

M . Annoni¹, F. Arleo¹, M. Guagliano^1,2

Structural Durability & Health Monitoring, Vol.6, No.1, pp. 1-16, 2010, DOI:10.3970/sdhm.2010.006.001

Abstract This work investigates the possibility to perform Water Jet Peening (WJP) by means of a standard Water Jet (WJ) cutting plant. The experimentation is carried out on 39NiCrMo3 specimens with the aim to find out the best working conditions of two different methods: the "in air WJP" and the "submerged WJP". Comparisons between the two methods and to previous experimentations in the reference literature are also presented. More >

C. A. Bronkhorst^1,2, A. R. Ross³, B. L. Hansen¹, E. K. Cerreta², J. F. Bingert²

CMC-Computers, Materials & Continua, Vol.17, No.2, pp. 149-174, 2010, DOI:10.3970/cmc.2010.017.149

Abstract A common sample geometry used to study shear localization is the "tophat": an axi-symmetric sample with an upper "hat" portion and a lower "brim" portion. The gage section lies between the hat and brim. The gage section length is on the order of 0.9 mm with deformation imposed through a Split-Hopkinson Pressure Bar system at maximum top-to-bottom velocity in the range of 10-25 m/sec. Detailed metallographic analysis has been performed on sections of the samples to quantify the topology and deformation state of the material after large deformation shear. These experiments performed with polycrystalline tantalum… More >

T.M. Hatem¹, M.A. Zikry¹

CMC-Computers, Materials & Continua, Vol.17, No.2, pp. 127-148, 2010, DOI:10.3970/cmc.2010.017.127

Abstract A three-dimensional multiple-slip dislocation-density-based crystalline formulation, and specialized finite-element formulations were used to investigate dislocation-density evolution and crack behavior in single-packet lath martensite in high strength martensitic steels. The formulation is based on accounting for variant morphologies and orientations, and initial dislocations-densities that are uniquely inherent to martensitic microstructures. The effects of loading plane with respect to the orientation o the habit plane are investigated. Furthermore, the formulation was used to investigate single-packet microstructure mapped directly from SEM/EBSD images of maraging and ausformed martensitic steel alloys. This analysis underscores that shear pipe effects in martensitic More >

I-L. Chang¹, W.-C. Ding

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.3, pp. 297-312, 2010, DOI:10.3970/cmes.2010.068.297

Abstract Molecular dynamics method incorporating with parallel computing technique was employed to study the mechanical properties of textured polycrystalline nanofilms with fixed out-of-plane normal direction. The grain size and film thickness effects on both the elastic and plastic properties of the copper nanofilm were examined. It is shown from the simulation that the elastic and plastic properties (i.e., Young’s modulus, Poisson’s ratio, biaxial yield stress, etc) of textured polycrystalline nanofilms depend on the grain size and the film thickness. As the grain size of the nanofilm become larger, the Young’s modulus and biaxial yield stress increase More >

Jai Hak Park¹, Maan Won Kim², Gennadiy P. Nikishkov³

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.3, pp. 269-296, 2010, DOI:10.3970/cmes.2010.068.269

Abstract A SGBEM-FEM alternating method had been proposed by Nikishkov, Park and Atluri for the analysis of three-dimensional planar and non-planar cracks and their growth. In the method, the symmetric Galerkin boundary element method is used for the crack solution in an infinite body and the finite element method is used to perform stress analysis for the uncracked body only. In this paper the method is extended further to analyze through-thickness cracks. Adequate shape of boundary element mesh is examined and it is found that the fictitious portion of the boundary element mesh, which is located More >

A. A. Abdulrazeg¹, J. Noorzaei^1,2, P. Khanehzaei¹, M. S. Jaafar¹, T. A. Mohammed¹

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.3, pp. 239-268, 2010, DOI:10.3970/cmes.2010.068.239

Abstract Development of temperature rise in massive concrete structure such as a roller compacted concrete dam is attributed to hydration of concrete and environmental boundary conditions. These thermal changes in the material affect the elastic, creep properties of the material, and in turn, the stress fields within the structure. Therefore, the effects of temperature on the properties of RCC materials( elastic, creep) has to be taken into account in order to determine the risk of the thermally induced cracking in these dams. In the present work an attempt has been made to consider the effect of More >

Chikit Au¹, Yiyu Cai², Jianmin Zheng³, Tony Woo⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.3, pp. 221-238, 2010, DOI:10.3970/cmes.2010.068.221

Abstract A protein model (such as a ribbon model) can be created from the atomic coordinates in the protein data base files. These coordinates are obtained by X-ray crystallography or NMR spectroscopy with the protein arbitrarily oriented. As such, identifying or comparing a novel structure with a known item using protein model in the protein data base can be a timely process since a large number of transformations may be involved. The identification efficiency will be improved if the protein models are uniformly oriented. This paper presents an approach to orient a protein model to generate More >

Chein-Shan Liu¹, Satya N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.3, pp. 299-326, 2010, DOI:10.3970/cmes.2010.064.299

Abstract We solve the Calderón inverse conductivity problem [Calderón (1980, 2006)], for an elliptic type equation in a rectangular plane domain, to recover an unknown conductivity function inside the domain, from the over-specified Cauchy data on the bottom of the rectangle. The Calderón inverse problem exhibitsthree-fold simultaneous difficulties: ill-posedness of the inverse Cauchy problem, ill-posedness of the parameter identification, and no information inside the domain being available on the impedance function. In order to solve this problem, we discretize the whole domain into many sub-domains of finite strips, each with a small height. Thus the Calderón… More >

J. Sladek¹, V. Sladek¹, P. Stanak¹, E. Pan²

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.3, pp. 267-298, 2010, DOI:10.3970/cmes.2010.064.267

Abstract The plate equations are obtained by means of an appropriate expansion of the mechanical displacement and electric potential in powers of the thickness coordinate in the variational equation of electroelasticity and integration through the thickness. The appropriate assumptions are made to derive the uncoupled equations for the extensional and flexural motion. The present approach reduces the original 3-D plate problem to a 2-D problem, with all the unknown quantities being localized in the mid-plane of the plate. A meshless local Petrov-Galerkin (MLPG) method is then applied to solve the problem. Nodal points are randomly spread… More >