Wen-Hwa Chen^1,2, Chun-Hung Wu¹, Hsien-Chie Cheng^3,4,5

CMC-Computers, Materials & Continua, Vol.25, No.3, pp. 195-214, 2011, DOI:10.3970/cmc.2011.025.195

Abstract The study aims at investigating the linear and volumetric thermal expansion coefficients (CTEs) at temperature below the Debye temperature and phase transformation behaviors at atmospheric pressure of carbon fullerenes, i.e., C₆₀, C₇₀ and C₈₀, through a modified Nosé-Hoover (NH) thermostat method incorporated with molecular dynamics (MD) simulation. The calculated results are compared with those obtained from the standard NH and "massive" NHC (MNHC) thermostats and also with the literature experimental and theoretical data. Results show that at temperature below the Debye temperature, the CTEs of the fullerene molecules would significantly decrease with a decreasing temperature and tend to become negative… More >

Hsin-Yu Chen¹, Nien-Ti Tsou^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.120, No.2, pp. 319-332, 2019, DOI:10.32604/cmes.2019.06447

Abstract Shape memory alloys has been widely applied on actuators and medical devices. The transformation temperature and microstructural evolution play two crucial factors and dominate the behavior of shape memory alloys. In order to understand the influence of the composition of the Ni-Ti alloys on the two factors, molecular dynamics was adopted to simulate the temperature-induced phase transformation. The results were post-processed by the martensite variant identification method. The method allows to reveal the detailed microstructural evolution of variants/phases in each case of the composition of Ni-Ti. Many features were found and having good agreement with those reported in the literature,… More >

M. Nagaraj^1,*, A. John Presin Kumar², C. Ezilarasan³, Rishab Betala⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.3, pp. 679-692, 2019, DOI:10.31614/cmes.2019.04924

Abstract The paper proposes a simulated 3D Finite Element Model (FEM) for drilling of Nickel based super alloy known as Nimonic C-263. The Lagrangian finite element model-based simulations were performed to determine the thrust force, temperature generation, effective stress, and effective strain. The simulations were performed according to the L27 orthogonal array. A perfect plastic work piece was assumed, and the shape is considered to be cylindrical. The spindle speed, feed rate, and point angle were considered as the input parameters. The work piece was modeled by Johnson–Cook (JC) material model and tungsten carbide (WC) was chosen as the drill bit… More >

Li Ding¹, Jiasheng Zhang,^1,2, Hongchang Sun^3,*

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.2, pp. 213-229, 2018, DOI:10.31614/cmes.2018.03981

Abstract In order to ensure the safety of fluid flow in deep-water submarine pipelines, a safe and energy-saving built-in skin effect electric heat tracing technology was adopted as the thermal management strategy. The magnetic field distribution of built-in skin effect heating system is analyzed based on the mechanism of built-in skin effect heating system, so as to obtain the equivalent circuit model of built-in skin effect electric heating system. Meanwhile, heating power is introduced as an intermediate variable to establish the relationship between power supply frequency and built-in skin effect heating temperature. Aiming at the skin effect electric heating system, an… More >

Yi Xue^1,2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.4, pp. 429-441, 2017, DOI:10.3970/cmes.2017.113.429

Abstract The lack of research on the effect of diffusion on methane extraction leads to low methane concentration and low utilization. The Comsol Multiphysics software is used to solve the numerical gas and solid coupled model which considers the diffusion of coal matrix, fracture seepage, permeability evolution and coal deformation. The simulation results reveal the effect of diffusion process on methane migration. The gas diffusion rate is relatively high in the initial stage. With the increase in time, the difference between coal fractures and coal matrix blocks becomes lower and the gas diffusion rate decreases gradually. The gas seepage rate decreases… More >

Chein-Shan Liu ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.99, No.5, pp. 371-391, 2014, DOI:10.3970/cmes.2014.099.371

Abstract We recover an unknown initial temperature for a nonlinear heat conduction equation u_t(x,t) = u_xx(x,t) + H(x,t,u,u_x), under the Cauchy boundary conditions specified on the left-boundary. The method in the present paper transforms the Cauchy problem into an inverse heat source problem to find F(x) in T_t(x,t) = T_xx(x,t) + H + F(x). By using the GL(N,R) Lie-group differential algebraic equations (LGDAE) algorithm to integrate the numerical method of lines discretized equations from sideways heat equation, we can fast recover the initial temperature and two boundary conditions on the right-boundary. The accuracy and efficiency are confirmed by comparing the exact… More >

Bingfei Liu¹, Guansuo Dui^2,3, Lijun Xue², Benming Xie¹

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.3, pp. 239-260, 2013, DOI:10.32604/cmes.2013.094.239

Abstract Analytical solutions are derived for the macroscopic behaviors of a Shape Memory Alloy (SMA) thick-walled cylinder subjected to internal pressure and radial temperature gradient. The Tresca transformation criterion and linear hardening are used. Equations are given for the radial and circumferential stresses, transformation strains and martensite volume fractions at both the elastic step and the transformation step. Numerical results are presented and in good agreement with the finite element simulations. More >

Cao Guohua¹, Zhu Zhencai¹, Peng Weihong², Wang Jinjie¹, Liu Zhi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.2, pp. 119-138, 2013, DOI:10.3970/cmes.2013.094.119

Abstract The single helical structure is twisted by surrounding helical units with clearance or not between two layers. In order to master the thermal expansion behavior, the theory has been developed for the analysis of these helical structures. The previously deduced linear expressions of thermal expansion coefficients for the gapless structure model (GM) is used and the analytical method is applied to the clearance structure model (CM) and clearance-gapless structure model(CGM) under two boundary conditions. For further evaluating the analytical expressions of two models, the finite element models of the single helical structure surrounding by helical units with lang lay and… More >

Kuo-Ning Chiang¹, Chan-Yen Chou², Chung-Jung Wu²,Chao-Jen Huang², Ming-Chih Yew²

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.1, pp. 85-96, 2008, DOI:10.3970/cmes.2008.037.085

Abstract An atomic-level analytical solution, together with a modified Morse potential, has been developed to estimate temperature-dependent thermal expansion coefficients (CTE) and elastic characteristics of bulk metals. In this study, inter-atomic forces are considered as a set of anharmonic oscillator networks which can be described by Morse potential, while the material properties can be defined by these inter-atomic forces; when temperature increases, the vibration of the anharmonic oscillator causes the phenomenon of temperature-dependent material properties. The results of analysis showed that the original Morse potential can give a reasonable prediction of the thermal expansion coefficients and elastic constants of metals at… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.14, No.2, pp. 77-90, 2006, DOI:10.3970/cmes.2006.014.077

Abstract In this paper we derive the first-order and second-order one-step GPS applied to the estimation of thermophysical properties. Solving the resultant algebraic equations, which usually converges within ten iterations, it is not difficult to estimate the unknown temperature-dependent thermal conductivity and heat capacity simultaneously, if some supplemented data of measured temperature at a time T is provided. When the measured temperature in the conducting slab is contaminated by noise, our estimated results are also good. The new method does not require any prior information on the functional forms of thermal conductivity and heat capacity. Numerical examples are examined to show… More >