Weijie Li¹, Haiming Huang^1,2, Bangcheng Ai³, Ye Tian¹

CMC-Computers, Materials & Continua, Vol.43, No.3, pp. 175-196, 2014, DOI:10.3970/cmc.2014.043.175

Abstract Physical and mathematical models are the key to analyze thermal behavior of charring materials in the thermal protection system of reentry vehicles subjected to aerodynamic heating. To explore the thermal behavior of charring ablator, we developed and compared two models (pyrolysis interface model and pyrolysis layer model) with pyrolysis and surface recession. Taking AVCOAT composites as an example, its nonlinear thermal behavior, which are caused by temperature dependent thermal properties, moving interfaces and moving boundary, were simulated using the calculation codes written respectively on the basis of the pyrolysis layer model and the pyrolysis interface model. Numerical results indicate that… More >

E. Ferretti¹

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 293-322, 2013, DOI:10.3970/cmc.2013.036.293

Abstract The Cell Method is applied in order to model the debonding mechanism in ceramic floor tiles subjected to positive thermal variation. The causes of thermal debonding, very usual in radiant heat floors, have not been fully clarified at the moment. There exist only a few simplified analytical approaches that assimilate this problem to an eccentric tile compression, but these approaches introduce axial forces that, in reality, do not exist. In our work we have abandoned the simplified closed form solution in favor of a numerical solution, which models the interaction between tiles and sub-base more realistically, when the positive thermal… More >

Sanjeev Saxena¹, Raghvendra Singh², Geeta Agnihotri²

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 257-270, 2013, DOI:10.3970/cmc.2013.036.257

Abstract The present numerical study is an attempt to understand the dependency of characteristic distance on the fracture specimen thickness and temperature. The presented work will be useful to establish the characteristic distance prediction methodology using three dimensional FEM model. Based on the methods proposed for the numerical prediction of characteristic distance, it comes out that it depends on fracture specimen thickness and finally it converges after a specified thickness of fracture specimen. In Armco iron material, characteristic distance varies in temperature ranges where dynamic strain ageing phenomenon is observed, initially decrease and then increases again. More >

Ching-Feng Yu¹, Wen-Hwa Chen^1,2, Kun-Ling Chen¹, Hsien-Chie Cheng^2,3

CMC-Computers, Materials & Continua, Vol.36, No.2, pp. 203-229, 2013, DOI:10.3970/cmc.2013.036.203

Abstract The investigation assesses the thermal-mechanical and thermodynamic properties of various graphene sheets using a modified Nosé-Hoover (NH) thermostat method incorporated with molecular dynamics (MD) simulation. The investigation begins with an exploration of their thermal-mechanical properties at atmospheric pressure, including Young’s modulus, shear modulus, Poisson’s ratio, specific heats and linear and volumetric coefficients of thermal expansion (CTE). Two definitions of the line change ratio (ΔL/L) are utilized to determine the linear CTE of graphene sheets, and the calculations are compared with each other and data in the literature. To estimate the volumetric CTE values, the Connolly surface method is applied to… More >

Qunfeng Liu¹, gping Shen²

CMC-Computers, Materials & Continua, Vol.17, No.1, pp. 59-76, 2010, DOI:10.3970/cmc.2010.017.059

Abstract Molecular Dynamics (MD) simulations have been performed using the EAM potential to investigate the deformation behaviors and mechanical properties of <100>/{100} gold nanowires with square cross-section at a certain strain rate under different temperatures ranging from 10 K to 700 K. It is found that <100>/{100} gold nanowires at high temperatures tend to form the extended stable nanobridges-Helical Multi-shell Structure (HMS), which is similar to the deformation behavior of <110> gold nanowires at room temperature reported in the previous experimental observations and simulations. The effect of temperature on the mechanical properties and deformation behaviors of gold nanowires was analyzed. The… More >

Shu-Feng Lee¹, Che-Wun Hong^1,2

CMC-Computers, Materials & Continua, Vol.12, No.3, pp. 223-236, 2009, DOI:10.3970/cmc.2009.012.223

Abstract Solid oxides, such as ceria (CeO₂) doped with cations of lower valance, are potential electrolytes for future solid oxide fuel cells. This is due to the theoretically high ionic conductivity at low operation temperature. This paper investigates the feasibility of two potential electrolytes which are samarium-doped ceria (SDC) and gadolinium-doped ceria (GDC) to replace the traditional yttria-stablized zirconia (YSZ). Molecular simulation techniques were employed to study the influence of different dopant concentrations at different operation temperatures on the ionic conductivity from the atomistic perspective. Simulation results show that the optimized ionic conductivity occurs at 11.11mol% concentration using both dopants of… More >

D. S. Liu¹, C. Y. Tsai¹, S. R. Lyu²

CMC-Computers, Materials & Continua, Vol.11, No.2, pp. 147-164, 2009, DOI:10.3970/cmc.2009.011.147

Abstract This study presents a novel numerical method for extracting the tempe -rature-dependent mechanical properties of the gold and aluminum thin-films. In the proposed approach, molecular dynamics (MD) simulations are performed to establish the load-displacement response of the thin substrate nanoindented at temperatures ranging from 300-900 K. A simple but effective procedure involving genetic algorithm (GA) and finite element method (FEM) is implemented to extract the material constants of the gold and aluminum substrates. The material constants are then used to construct the corresponding stress-strain curve, from which the elastic modulus, yield stress and the tangent modulus of the thin film… More >

Deepak A Apte¹, Ranjan Ganguli^1,2

CMC-Computers, Materials & Continua, Vol.10, No.2, pp. 139-162, 2009, DOI:10.3970/cmc.2009.010.139

Abstract The influence of electric field and temperature on power consumption of piezoelectric actuated integrated structure is studied by using a single degree of freedom mass-spring-damper system model coupled with a piezoactuator. The material lead zirconate titanate, is considered as it is capable of producing relatively high strains (e.g., 3000με). Actuators are often subject to high electric fields to increase the induced strain produced, resulting in field dependant piezoelectric coefficient d₃₁, dielectric coefficient ε₃₃ and dissipation factor δ. Piezostructures are also likely to be used across a wide range of temperatures in aerospace and undersea operations. Again, the piezoelectric properties can… More >

CMC-Computers, Materials & Continua, Vol.10, No.1, pp. 65-96, 2009, DOI:10.3970/cmc.2009.010.065

Abstract This work proposed an alternative formulation for the prediction of martensite start temperature (Ms) of Fe-Mn-Si shape memory alloys (SMAs) depending on the various compositions and heat treatment techniques by using Neural Network (NN) and genetic programming (GP) soft computing techniques. The training and testing patterns of the proposed NN and GP formulations are based on well established experimental results from the literature. The NN and GP based formulation results are compared with experimental results and found to be quite reliable with a very high correlation (R2=0.955 for GEP and 0.999 for NN). More >