Richard K. F. Lee¹, James M. Hill²

CMC-Computers, Materials & Continua, Vol.20, No.1, pp. 85-100, 2010, DOI:10.3970/cmc.2010.020.085

Abstract In this study, we investigate the mechanics of a metallofullerene shuttle memory device, comprising a metallofullerene which is located inside a closed carbon nanotube. The interaction energy for the system is obtained from the 6-12 Lennard-Jones potential using the continuum approximation, which assumes that a discrete atomic structure can be replaced by an average atomic surface density. This approach shows that the system has two equal minimum energy positions, which are symmetrically located close to the tube extremities, and therefore it gives rise to the possibility of being used as a two-state memory device. On one side the encapsulated metallofullerene… More >

Lutz Nasdala¹ , Andreas Kempe¹ and Raimund Rolfes¹

CMC-Computers, Materials & Continua, Vol.19, No.1, pp. 57-104, 2010, DOI:10.3970/cmc.2010.019.057

Abstract In order to understand the underlying mechanisms of inelastic material behavior and nonlinear surface interactions, which can be observed on macroscale as damping, softening, fracture, delamination, frictional contact etc., it is necessary to examine the molecular scale. Force fields can be applied to simulate the rearrangement of chemical and physical bonds. However, a simulation of the atomic interactions is very costly so that classical molecular dynamics (MD) is restricted to structures containing a low number of atoms such as carbon nanotubes. The objective of this paper is to show how MD simulations can be integrated into the finite element method… More >

Veturia Chiroiu¹, Ligia Munteanu² and Antonio S. Gliozzi³

CMC-Computers, Materials & Continua, Vol.19, No.1, pp. 1-16, 2010, DOI:10.3970/cmc.2010.019.001

Abstract This paper develops a mechanical model for multifunctional reinforced carbon nanotube (CNT) beams. The model is obtained by introducing the couple stresses into the constitutive equations of linear viscoelastic theory. The material functions are determined using the homogenization method. More >

Veturia Chiroiu¹, Ligia Munteanu¹, Pier Paolo Delsanto²

CMC-Computers, Materials & Continua, Vol.16, No.1, pp. 75-100, 2010, DOI:10.3970/cmc.2010.016.075

Abstract Conventional continuum theories are unable to capture the observed indentation size effects, due to the lack of intrinsic length scales that represent the measures of nanostructure in the constitutive relations. In order to overcome this deficiency, the Toupin-Mindlin strain gradient theory of nanoindentation is formulated in this paper and the size dependence of the hardness with respect to the depth and the radius of the indenter for multiple walled carbon nanotubes is investigated. Results show a peculiar size influence on the hardness, which is explained via the shear resistance between the neighboring walls during the buckling of the multiwalled nanotubes. More >

Xiaoyi Liang¹, Zhen Yang^1,2, Xingsheng Gu³, Licheng Ling¹

CMC-Computers, Materials & Continua, Vol.13, No.2, pp. 135-152, 2009, DOI:10.3970/cmc.2009.013.135

Abstract Supercapacitors, also called electrical double-layer capacitors (EDLCs), occupy a region between batteries and dielectric capacitors on the Ragone plot describing the relation between energy and power. BET specific surface area and specific capacitance are two important electrochemical property parameters for activated carbon EDLCs, which are usually tested by experimental method. However, it is misspent time to repeat lots of experiments for EDLCs' studies. In this investigation, we developed one theoretical model based on improved particle swarm optimization algorithm back propagation (PSO-BP) neural network (NN) to simulate and optimize BET specific surface area and specific capacitance. Comparative studies between the predicted… More >

Hsien-Chie Cheng¹, Yu-Chen Hsu², Wen-Hwa Chen²

CMC-Computers, Materials & Continua, Vol.11, No.2, pp. 127-146, 2009, DOI:10.3970/cmc.2009.011.127

Abstract Due to the limitation of fabrication technologies nowadays, structural or atomistic defects are often perceived in carbon nanotubes (CNTs) during the manufacturing process. The main goal of the study aims at providing a systematic investigation of the effects of atomistic defects on the nanomechanical properties and fracture behaviors of single-walled CNTs (SWCNTs) using molecular dynamics (MD) simulation. Furthermore, the correlation between local stress distribution and fracture evolution is studied. Key parameters and factors under investigation include the number, type (namely the vacancy and Stone-Wales defects), location and distribution of defects. Results show that the nanomechanical properties of the CNTs, such… More >

Yeau-Ren Jeng¹,Ping-Chi Tsai¹,Guo-Zhe Huang¹, I-Ling Chang¹

CMC-Computers, Materials & Continua, Vol.11, No.2, pp. 109-126, 2009, DOI:10.3970/cmc.2009.011.109

Abstract This study performs a series of Molecular Dynamics (MD) and Molecular Statics (MS) simulations to investigate the mechanical properties of single-walled carbon nanotubes (SWCNTs) under a uniaxial tensile strain. The simulations focus specifically on the effects of the nanotube helicity, the nanotube diameter and the percentage of vacancy defects on the bond length, bond angle and tensile strength of zigzag and armchair SWCNTs. In this study, a good agreement is observed between the MD and MS simulation results for the stress-strain response of the SWCNTs in both the elastic and the plastic deformation regimes. The MS simulations reveal that in… More >

S. Mukherjee¹, S. Chakraborty², I. Manna^1,3

CMC-Computers, Materials & Continua, Vol.10, No.3, pp. 217-228, 2009, DOI:10.3970/cmc.2009.010.217

Abstract Influence of power density and interaction time for austenitisation during laser surface hardening of plain carbon eutectoid steel has been investigated. The analysis involves numerical prediction of thermal and solute diffusion profiles and thereby, the time needed for homogenization of austenite for different processing conditions. Experimental results provide qualitative validation. More >

J. Ghanbari¹, R. Naghdabadi^1,2

CMC-Computers, Materials & Continua, Vol.10, No.1, pp. 41-64, 2009, DOI:10.3970/cmc.2009.010.041

Abstract Continuum-based modeling of nanostructures is an efficient and suitable method to study the behavior of these structures when the deformation can be considered homogeneous. This paper is concerned about multiscale nonlinear tensorial constitutive modeling of carbon nanostructures based on the interatomic potentials. The proposed constitutive model is a tensorial equation relating the second Piola-Kirchhoff stress tensor to Green-Lagrange strain tensor. For carbon nanotubes, some modifications are made on the planar representative volume element (RVE) to account for the curved atomic structure resulting a non-planar RVE. Using the proposed constitutive model, the elastic behavior of the graphene sheet and carbon nanotube… More >

Shen Yubin¹, Xie Huicai^1,2, Den Wei¹

CMC-Computers, Materials & Continua, Vol.3, No.2, pp. 49-54, 2006, DOI:10.3970/cmc.2006.003.049

Abstract Bonding an overlay of new concrete onto the damaged concrete is a usual repair method. Because of the different shrinkage rate of the new and old concrete, restrained shrinkage cracks will appear in the new concrete. The cracks will reduce durability and strength of the repaired structure. A new repair method using an interface layer of carbon fiber reinforced cement mortar between new and old concrete was developed in this paper. The new method was found to be very effective in reducing shrinkage cracking of repaired beams and slabs. Comparing with normal repaired beams, the maximum observed width of the… More >