Min Ki Kim¹, Seung Jo Kim²

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.4, pp. 297-332, 2012, DOI:10.3970/cmes.2012.084.297

Abstract Hybrid parallelization of multifrontal solution method and its parallel performances in a multicore distributed parallel computing architecture are represented in this paper. To utilize a state-of-the-art multicore computing architecture, parallelization of the multifrontal method for a symmetric multiprocessor machine is required. Multifrontal method is easier to parallelize than other direct solution methods because the solution procedure implies that the elimination of unknowns can be executed simultaneously. This paper focuses on the multithreaded parallelism and mixing distributed algorithm and multithreaded algorithm together in a unified software. To implement the hybrid parallelized algorithm in a distributed shared memory environment, two innovative ideas… More >

Ryuta Imai¹, Masatoshi Nakagawa²

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.3, pp. 253-282, 2012, DOI:10.3970/cmes.2012.084.253

Abstract In order to evaluate seismic response of fast breeder reactors, finite element analysis for core vibration with contact/impact is performed so far. However a full model analysis of whole core vibration requires huge calculation times and memory sizes. In this research, we propose an acceleration method of reducing the number of degrees of freedom to be solved until converged for nonlinear contact problems. Furthermore we show a sufficient condition for the algorithm to work well and discuss its efficiency and a generalization of the algorithm. In particular we carry out the full model analysis to show that our method can… More >

Sharnappa¹, N. Ganesan², Raju Sethuraman³

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.2, pp. 121-144, 2007, DOI:10.3970/cmes.2007.018.121

Abstract This article presents the study on buckling and free vibration behavior of sandwich general shells of revolution under thermal environment using Wilkins theory. The temperature assumes to be uniform over the shell structure. The numerical analysis is based on the semi-analytical finite element method applicable to thick shells. The analysis is carried out for different geometry such as truncated conical and hemispherical shells with various facing and core materials under clamped-clamped boundary condition. The parametric study is carried out for different core to facing (t_c / t_f) thickness ratio by considering the temperature dependent and independent material properties of the… More >

Zhenyu Xue¹, Ashkan Vaziri¹, John W. Hutchinson¹

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.1, pp. 79-96, 2005, DOI:10.3970/cmes.2005.010.079

Abstract A constitutive model for the elastic-plastic behavior of plastically compressible orthotropic materials is proposed based on an ellipsoidal yield surface with evolving ellipticity to accommodate non-uniform hardening or softening associated with stressing in different directions. The model incorporates rate-dependence arising from material rate-dependence and micro-inertial effects. The basic inputs are the stress-strain responses under the six fundamental stress histories in the orthotropic axes. Special limits of the model include classical isotropic hardening theory, the Hill model for incompressible orthotropic solids, and the Deshpande-Fleck model for highly porous isotropic foam metals. A primary motivation is application to metal core structure in… More >

Karin Lin¹, D. C. Chrzan²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.2, pp. 201-212, 2002, DOI:10.3970/cmes.2002.003.201

Abstract The 90° partial dislocation in Si is studied using a combination of Tersoff potentials and isotropic elasticity theory. Both periodic supercells and cylindrical cells are employed and the results compared. The dislocation core radius is extracted by fitting the results of atomic scale calculations to an expression for the elastic energy of the dislocation. The energy differences between two proposed reconstructions of the dislocation core are computed and found to depend systematically on the stress field imposed on the dislocation. It is suggested that hydrostatic stresses may introduce a core transformation. More >

L. Gornet¹, S. Marguet², G. Marckmann³

CMC-Computers, Materials & Continua, Vol.4, No.2, pp. 63-74, 2006, DOI:10.3970/cmc.2006.004.063

Abstract The purpose of the present study is to determine the components of the effective elasticity tensor and the failure properties of Nomex^® honeycomb cores. In order to carry out this study, the NidaCore software, a program dedicated to Nomex®Cores predictions, has been developed using the Finite Element tool Cast3M-CEA. This software is based on periodic homogenization techniques and on the modelling of structural instability phenomena. The homogenization of the periodic microstructure is realized thanks to a strain energy approach. It assumes the mechanical equivalence between the microstructures of a RVE and a similar homogeneous macroscopic volume. The key point of… More >

Kemal Akyol^1,*, Baha Şen²

CMC-Computers, Materials & Continua, Vol.61, No.1, pp. 69-80, 2019, DOI:10.32604/cmc.2019.08143

Abstract The popularity of news, which conveys newsworthy events which occur during day to people, is substantially important for the spectator or audience. People interact with news website and share news links or their opinions. This study uses supervised learning based machine learning techniques in order to predict news popularity in social media sources. These techniques consist of basically two phrases: a) the training data is sent as input to the classifier algorithm, b) the performance of pre-learned algorithm is tested on the testing data. And so, a knowledge discovery from the data is performed. In this context, firstly, twelve datasets… More >

G. Smith¹, E. Schlangen², P.E.J. Flewitt³, A.G. Crocker⁴, A. Hodgkins⁵

CMC-Computers, Materials & Continua, Vol.51, No.3, pp. 163-185, 2016, DOI:10.3970/cmc.2016.051.163

Abstract Two linked models have been developed to explore the relationship between the amount of porosity arising in service from both radiolytic oxidation and fast neutron damage that influences both the strength and the force-displacement (load-displacement) behaviour and crack propagation in pile grade A graphite used as a nuclear reactor moderator material. Firstly models of the microstructure of the porous graphite for both unirradiated and irradiated graphite are created. These form the input for the second stage, simulating fracture in lattice-type finite element models, which predicts force (load)-displacement and crack propagation paths. Microstructures comprising aligned filler particles, typical of needle coke,… More >

Lixin Cong¹, Yuguo Sun^1,2, Xinzhu Wang³

CMC-Computers, Materials & Continua, Vol.47, No.1, pp. 1-14, 2015, DOI:10.3970/cmc.2015.047.001

Abstract In order to solve bending behavior difference of corrugated structure in L andWorientation, bending response for composite sandwich beams with foldcores of three different wall thicknesses were experimentally and numerically investigated. Effect of the cell walls thickness on the strength and failure behavior of the composite sandwich beams with L and W orientations was also examined. The deformation mode was obtained by the numerical method; a constitutive law of laminated material has been incorporated into a finite element (FE) analysis program. Numerical calculations give accurate prediction to the bending response of foldcore composite sandwich beams comparing with experiments. Structural flexural… More >

Y. T. Wu¹, J. Z. Cui², Y. F. Nie³, Y. Zhang³

CMC-Computers, Materials & Continua, Vol.42, No.3, pp. 205-226, 2014, DOI:10.3970/cmc.2014.042.205

Abstract Core–shell particle–filled PA6/EPDM–g–MA/HDPE ternary blend has excellent mechanical properties. In this paper, effective elastic properties and tensile yield strength of the ternary blend are predicted by the second–order two– scale method, to investigate the relationship between morphology and mechanical properties. The method and the limit analysis for predicting mechanical properties of random heterogeneous materials are briefly introduced. Realistic morphology of the ternary blend including both core–shell particles and pure particles is simulated, and finite element mesh is generated. The unified strength theory is embedded in the method for the convenience of selecting a suitable yield criterion. The effective elastic moduli… More >