A. Ramachandra Murthy¹, Nagesh R. Iyer¹, B.K. Raghu Prasad²

CMC-Computers, Materials & Continua, Vol.31, No.3, pp. 229-252, 2012, DOI:10.3970/cmc.2012.031.229

Abstract This paper presents the advanced analytical methodologies such as Double- G and Double - K models for fracture analysis of concrete specimens made up of high strength concrete (HSC, HSC1) and ultra high strength concrete. Brief details about characterization and experimentation of HSC, HSC1 and UHSC have been provided. Double-G model is based on energy concept and couples the Griffith's brittle fracture theory with the bridging softening property of concrete. The double-K fracture model is based on stress intensity factor approach. Various fracture parameters such as cohesive fracture toughness (K_Ic^c), unstable fracture toughness (K_Ic^un) and initiation fracture toughness… More >

Yang Liu^1,*, Yue Qiao², Tiange Li³

CMES-Computer Modeling in Engineering & Sciences, Vol.120, No.1, pp. 177-201, 2019, DOI:10.32604/cmes.2019.06338

Abstract This paper studies the effect of ice resistance on the icebreaking capacity and speed of an icebreaking vessel. We combine an improved Correct Smoothed Particle Method (CSPM) with a material low-speed collision fracture model to numerically simulate the continuous icebreaking and rolling process of crushed. Using this model, we investigate the icebreaking resistance and immersion resistance during the icebreaking process, taking into account the fluid (water) as the elastic boundary support and the fluid-solid coupling interaction. We compare the icebreaking resistance and broken ice fracture shapes obtained by the numerical calculation with the theoretical analytical results, and thus validate the… More >

Davood Afshari^1,*, Soheil Mirzaahamdi¹, Zuheir Barsoum²

CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.2, pp. 275-290, 2019, DOI:10.31614/cmes.2019.03880

Abstract The use of magnesium alloys has been rapidly increased due to their ability to maintain high strengths at light weights. However weldability of steels and aluminum alloys by using resistance spot weld (RSW) process is a major issue, because it cannot be directly utilized for magnesium alloys. In this study, a structural-thermal-electrical finite element (FE) model has been developed to predict the distribution of residual stresses in RSW AZ61 magnesium alloy. Thermophysical and thermomechanical properties of AZ61 magnesium alloy have been experimentally determined, and have been used in FE model to increase the accuracy of the model. X-ray diffraction (XRD)… More >

Wenxin Wang^1,2, Dalin Tang², Boyan Mao¹, Bao Li¹, Xi Zhao³, Jian Liu⁴, Youjun Liu^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.116, No.2, pp. 163-173, 2018, DOI: 10.31614/cmes.2018.04219

Abstract Fractional flow reserve (FFR) is the gold standard to identify individual stenosis causing myocardial ischemia in catheter laboratory. The purpose of this study is to present a fast simulation method to estimate FFR value of a coronary artery, which can evaluate the performance of vascular stenosis, based on resistance boundary conditions. A patient-specific 3-dimensional (3D) model of the left coronary system with intermediate diameter stenosis was reconstructed based on the CTA images. The resistance boundary conditions used to simulate the coronary microcirculation were computed based on anatomical reconstruction of coronary 3D model. This study was performed by coupling the 3D… More >

Wen-Hwa Chen^1,2, Ching-Feng Yu¹, Hsien-Chie Cheng^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.2, pp. 119-131, 2014, DOI:10.3970/cmes.2014.100.119

Abstract The aim of the study is to investigate the interactions between Sn adatoms in a solder bump and three typical Sn-based intermetallic compounds (IMCs) surface, i.e., Cu₃Sn, Cu₆Sn₅, and Ni₃Sn₄, at the atomistic scale. The adsorption energy, average bond length, and bond population of the Sn/Cu₃Sn, Sn/Cu₆Sn₅,and Sn/Ni₃Sn₄ systems are calculated through the first-principles density functional theory (DFT) calculation to investigate how the Sn adatoms influence the IMC surface. The calculated results show that the Sn atoms on the Cu₃Sn (0 0 1) surface hold the largest adsorption energy, average bond length and bond population, implying that the Cu₃Sn (0… More >

Deli Gao^1,2, Lianzhong Sun^1,3, Hongshu Wei⁴, Shunwen Wang⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 143-162, 2012, DOI:10.3970/cmes.2012.089.143

Abstract Due to the complexity of forces acting on the down-hole tubular strings in extended reach drilling (ERD), the factors which influence the process should be taken into account as much as possible, in order to predict the down-hole drag & torque more accurately. This can help us to identify and prevent the problems related to downhole drag & torque in ERD. The effects of such factors, as the tubular buckling, the buoyancy, the mechanical resistance and the friction reducer, on down-hole drag & torque, are taken into account in this paper, in order to improve the accuracy of the prediction… More >

Xuejun Hou^1,2, Deli Gao¹, Zhonghou Shen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 97-110, 2012, DOI:10.3970/cmes.2012.089.097

Abstract Microhole drilling (MHD) is a new frontier drilling technology in which the diameter of wellbore is less than 88.9mm and coiled tubing (CT) is used as drill string. The CT wound around reel for MHD has small bending radius and large length to result in large circulating flow resistance and affect normal MHD circulation. The calculation model for curvature radius and length of CT wound around reel are established by analyzing the relationships among the various geometrical parameters of the reel system. The calculation model is combined with Dean number and power-law fluid state equation to put forward the calculation… More >

Donghuan Liu¹, Xiaoping Zheng^1,2, Yinghua Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.3, pp. 263-300, 2009, DOI:10.3970/cmes.2009.039.263

Abstract A discontinuous Galerkin (DG) finite element method for the heat conduction problems with local high gradient and thermal contact resistance is presented. The DG formulation is constructed by employing the stabilization term and the Bassi-Rebay numerical flux term. The stabilization term is defined by a penalization of the temperature jump at the interface. By eliminating the penalization term of the temperature jump in the region of local high gradient and imperfect contact interfaces, the present DG method is applied to solve problems involving local high gradient and thermal contact resistance where the numerical flux is obtained from the definition of… More >

L.K. Keppas¹, G.I. Giannopoulos¹, N.K. Anifantis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 181-196, 2008, DOI:10.3970/cmes.2008.025.181

Abstract In the present paper a boundary element procedure is formulated to treat two-dimensional time dependent thermo-elastic contact problems incorporating thermal resistance along the contacting surfaces. The existence of pressure-dependent thermal contact leads to coupling of temperature and stress fields. Therefore, the inherent non-linearity of the problem demands simultaneous treating of both thermal and mechanical boundary integral equations while iterative procedures are introduced to ensure equilibrium of mechanical and thermal contact conditions at each step of the process. The transient behavior of interfacial cracks in bimaterial solids when undergo thermal shock in the presence of partial crack closure and thermal contact… More >

L. Wang¹, S. Zhang, W. M. Gao, X. Wang

CMES-Computer Modeling in Engineering & Sciences, Vol.20, No.1, pp. 11-20, 2007, DOI:10.3970/cmes.2007.020.011

Abstract In this paper, the penetration of a knife through a plain woven fabric is simulated with the finite element method to understand the process of stabbing and the mechanism of fiber breakage. The model focuses on the study of the deformation of individual yarns, and the effects of their material properties and fabric structure on the stabbing resistant force. The performance of the fabric is analyzed as a response of stabbing and the stress distributions in yarn transverse and longitudinal directions. An equation derived from energy and momentum conservations of the knife is proposed to predict the depth of the… More >