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  • Open Access


    Modeling Intergranular Stress Corrosion Cracking A Voronoi-Markovian-Monte Carlo Approach

    M.A. Arafin, J.A. Szpunar

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.3, pp. 59-60, 2009, DOI:10.3970/icces.2009.013.059

    Abstract This paper introduce a novel approach for face image segmentation base on Voronoi Diagram (VD) technique. We used intensity value and region pixels value for enhance preprocessing step on gray-scale image. The method for locating and extraction face/head boundary are applied feature point of the original image which are useful dual tessellation of the VD is know as Delaunay Triangulation (DT). A target of experiment is reported face image segmentation that uses still face image from BioID database. The result of this method clearly demonstrates the segmentation which performs in comparison with another method in quality of gray value and… More >

  • Open Access


    On the Validity of the Fracture Mechanics Approach to Hydrogen Assisted Cracking

    J. Toribio1, V. Kharin2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.3, pp. 135-140, 2008, DOI:10.3970/icces.2008.007.135

    Abstract This paper deals with the meaning and significance of the fracture mechanics approach to hydrogen assisted cracking, analyzing the question of K-dominance not only over the purely mechanical aspects, but also over the environmental (physicochemical) events. Two key factors able to violate the uniqueness of the crack growth kinetics curve v = v(K) are discussed: the role of far field (the stress-strain field which is not K-dominated) and the effect of the history of hydrogenation and crack growth. The far field is shown to have a minor effect on near-tip hydrogen diffusion, and thus it can only widen the scatter… More >

  • Open Access


    Analysis and Numerical Simulation for Tunnelling Through Coal Seam Assisted by Water Jet

    Dengfeng Su1, Yong Kang1,2,*, Xiaochuan Wang2, andan Zheng1, DongyangLi1, Binyuan Yan1, Fuwen Yan1

    CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.5, pp. 375-393, 2016, DOI:10.3970/cmes.2016.111.375

    Abstract Tunnel though coal seam is one of the most difficult tunnels since its risk of coal and gas outburst and the complex geological conditions. According to the directional cutting of water jet and the characteristic of the coal seam and rock mass, this paper presents a new method of tunnelling though coal seam assisted by water jet slotting, which can be divided into improving permeability of coal seam and directional cracking in the rock mass. The mechanism of improving permeability of coal seam was stated, and the crack criterion of rock during blasting was established based on fracture theory. Then,… More >

  • Open Access


    Computational Modeling of Shock and Impact Response of Alumina

    A. M. Rajendran1, D. J. Grove2

    CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 367-380, 2002, DOI:10.3970/cmes.2002.003.367

    Abstract This paper presents detailed computational analyses investigating the ability of constitutive relationships to describe the response of a 99.5% pure alumina (AD995) subjected to a wide range of stress/strain loading states. Using a shock-wave-propagation-based finite element code, one and two-dimensional simulations were performed for the following shock and impact configurations: plate-on-plate impact; rod-on-rod impact; single-density plate-on-rod impact; graded-density plate-on-rod impact; and rod penetration into a thick plate. The detailed analyses presented in this paper include a model constant sensitivity study through comparisons of computed wave profiles with experimental measurements. More >

  • Open Access


    3D Higher-OrderX-FEM Model for the Simulation of Cohesive Cracks in Cementitious Materials Considering Hygro-Mechanical Couplings

    C. Becker1, S. Jox2, G. Meschke3

    CMES-Computer Modeling in Engineering & Sciences, Vol.57, No.3, pp. 245-278, 2010, DOI:10.3970/cmes.2010.057.245

    Abstract A three-dimensional numerical model based on the Extended Finite Element Method (X-FEM) is presented for the simulation of cohesive cracks in cementitious materials, such as concrete, in a hygro-mechanical framework. Enhancement functions for the small scale resolution of the displacement jump across cracks in the context of the X-FEM is used in conjunction with a higher order family of hierarchical shape functions for the representation of the large scale displacement field of the investigated structure. Besides the theoretical and computational formulation in a multiphase context, aspects of the implementation, such as integration and crack tracking algorithms, are discussed. Representative numerical… More >

  • Open Access


    Modeling of the Inhibition-Mechanism Triggered by `Smartly' Sensed Interfacial Stress Corrosion and Cracking

    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 >

  • Open Access


    Optimization of Industrial Fluid Catalytic Cracking Unit having Five Lump Kinetic Scheme using Genetic Algorithm

    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 >

  • Open Access


    Micromechanics of Hydride Formation and Cracking in Zirconium Alloys

    J. Lufrano1, P. Sofronis1

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 119-132, 2000, DOI:10.3970/cmes.2000.001.279

    Abstract Transient hydrogen diffusion and hydride formation coupled with material deformation are studied in Zr-2.5Nb alloys used in the pressure tubes of CANDU nuclear generating stations. The energetics of the hydride formation is revisited and the terminal solid solubility of hydrogen in solution is defined on the basis of the total elastoplastic work done on the system by the forming hydride and the external loads. Probabilistic precipitation of hydride is modeled in the neighborhood of a crack tip under mode I plane strain loading and a uniform initial hydrogen concentration below the stress free terminal solid solubility. Finite element analysis is… More >

  • Open Access


    Cracking of GSO Single Crystal Induced by Thermal Stress

    N. Miyazaki1, T. Tamura2, K. Yamamoto1

    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 99-106, 2000, DOI:10.3970/cmes.2000.001.099

    Abstract Quantitative estimation of the failure of a gadolinium orthosilicate (Gd2SiO5, hereafter abbreviated as GSO) single crystal induced by thermal stress was investigated. A GSO cylindrical test specimen was heated in a silicone oil bath, then subjected to large thermal stress by room temperature silicone oil. Cracking occurred during cooling. The transient heat conduction analysis was performed to obtain temperature distribution in the test specimen at the time of cracking, using the surface temperatures measured in the test. Then the thermal stress was calculated using the temperature profile of the test specimen obtained from the heat conduction analysis. It is found… More >

  • Open Access


    Prediction of Interfacial Cracking due to Differential Drying Shrinkage of Concrete in Precast Shell Pier Cap

    Kyong Pil Jang1, Je kuk Son2, Seung Hee Kwon1,3

    CMC-Computers, Materials & Continua, Vol.38, No.3, pp. 155-173, 2013, DOI:10.3970/cmc.2013.038.155

    Abstract In a precast shell pier cap, cracking at the interface between the precast shell and the cast-in-place concrete may happen due to differences between the drying shrinkage of the inner and the outer concrete. The objective of this study is to establish a prediction method for interfacial cracking that will consider the real mechanism of differential drying shrinkage and creep. The main parameters used in the analysis were determined from experiments for a concrete mix that is applied to the manufacturing of pier caps. The variation of internal relative humidity over time was first calculated based on the nonlinear moisture… More >

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