Zhi Yuan Cui¹, Jiu Hui Wu¹, Di Chen Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.2, pp. 149-156, 2011, DOI:10.3970/cmes.2011.071.149

Abstract A quantitative rule of the vibrated granular media's energy dissipation is obtained by adopting the turbulence theory in this letter. Our results show that, similar to the power spectrum in fully developed fluid turbulence as described in Kolmogorov's theory, the power spectrum of vibrated granular media also exhibits a k - 5 / 3 (k is the wave number) power which characterizes the local isotropic flow. What's more, the mean energy dissipation rate in vibrated granular media rises with the increase of particle size and volume ratio. The theoretical results in this letter can be verified by the previous experimental… More >

A. Idesman ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.2, pp. 111-148, 2011, DOI:10.3970/cmes.2011.071.111

Abstract The paper deals with the following issues of existing time-integration methods for a semi-discrete system of elastodynamics equations: a) the quantification and the suppression of spurious high frequencies; b) the selection of the amount of numerical dissipation for a time-integration method; and c) accurate time integration of low modes. The finite element method used in the paper or other methods can be applied for the space discretization. A new two-stage time-integration procedure consisting of basic computations and the filtering stage is developed. For accurate integration of all frequencies, a time-integration method with zero (or small) numerical dissipation is applied for… More >

Shuncai Li^1,2,3, Zhengzhu Dong², Dan Ma²

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.2, pp. 93-110, 2011, DOI:10.3970/cmes.2011.071.093

Abstract Weak local support is a very common phenomenon in roadway support engineering. It is a problem that needs to be studied thoroughly at the theoretical level. So far, the literature on stress field theory of rock surrounding a roadway is largely restricted to analytical solutions of stress for roadways with a uniform support or no support at all. The corresponding stress solution under conditions of local or weak local support has not been provided. Based on a mechanical model of weak local support at the boundary of a circular roadway and the boundary element method on boundary value problems of… More >

G. Shi ¹, P. Zhao ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.1, pp. 67-92, 2011, DOI:10.3970/cmes.2011.071.067

Abstract Based on molecular mechanics and the concept of flexible connection used in the flexibly connected frames, a new structural mechanics model, a 2-D frame composed of anisotropic beams and flexible connections, is proposed for the simulation of the static and dynamic flexural behavior of monolayer graphene. The equivalent beam representing the C-C bond in the new molecular structural mechanics (MSM) model has two salient features compared with other MSM models presented for the analysis of carbon nanotubes: one is that the flexible connections at the beam ends are used to account for the bond-angle variations between the C-C bonds of… More >

Seyed Mahmoud Hosseini¹, Farzad Shahabian²,Jan Sladek³, Vladimir Sladek³

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.1, pp. 39-66, 2011, DOI:10.3970/cmes.2011.071.039

Abstract The thermo-elastic wave propagation based on Green-Naghdi (GN) coupled thermo-elasticity (without energy dissipation) is studied in a functionally graded thick hollow cylinder considering uncertainty in constitutive mechanical properties under thermal shock loading. The meshless local Petrov-Galerkin method accompanied with Monte-Carlo simulation is developed to solve the stochastic boundary value problem. In the presented method, the mechanical properties of FGM are considered to be as random variables with Gaussian distribution and mean values equal to deterministic values reported in previous works, which are generated using Monte-Carlo simulation with various coefficients of variations (COVs). The time evolution for transient problems is treated… More >

S. Abbasbandy^1,2, V. Sladek³, A. Shirzadi¹, J. Sladek³

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.1, pp. 15-38, 2011, DOI:10.3970/cmes.2011.071.015

Abstract This paper deals with the development of a new method for solution of initial-boundary value problems governed by a couple of nonlinear diffusion equations occurring in the theory of self-organization in non-equilibrium systems. The time dependence is treated by linear interpolation using the finite difference method and the semi-discrete partial differential equations are considered in a weak sense by using the local integral equation method with approximating 2-d spatial variations of the field variables by the Moving Least Squares. The evaluation techniques are discussed and the applicability of the presented method is demonstrated on two illustrative examples with exact solutions… More >

J.A. Ferreira^2,3, P. de Oliveira², P. Silva⁴, J.N. Murta⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.1, pp. 1-14, 2011, DOI:10.3970/cmes.2011.071.001

Abstract Mathematical models to describe drug concentration profiles of topically administered drug in the anterior chamber aqueous humor have been proposed by several authors. The aim of this paper is to present a mathematical model to predict the drug concentration in the anterior chamber when a therapeutical contact lens with the drug entrapped in nanoparticles is used. More >

J. Sladek¹, V. Sladek¹, Ch. Zhang², M. Wünsche²

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.2, pp. 185-220, 2010, DOI:10.3970/cmes.2010.068.185

Abstract A meshless method based on the local Petrov-Galerkin approach is proposed to solve initial-boundary value crack problems of piezoelectric solids with nonlinear electrical boundary conditions on crack faces. Homogeneous and continuously varying material properties of the piezoelectric solid are considered. Stationary governing equations for electrical fields and the elastodynamic equations with an inertial term for mechanical 2-D fields are considered. Nodal points are spread on the analyzed domain, and each node is surrounded by a small circle for simplicity. The spatial variation of displacements and electric potential are approximated by the Moving Least-Squares (MLS) scheme. After performing the spatial integrations,… More >

V.C. Mariani¹, V. J. Neckel², L. S. Coelho³

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.2, pp. 167-184, 2010, DOI:10.3970/cmes.2010.068.167

Abstract In this study an inverse heat conduction problem using two optimization methods to estimate apparent thermal diffusivity at different drying temperatures is solved. Temperature and moisture versus time were obtained numerically using heat and mass transfer equations with drying temperatures in the range between 20°C to 70°C. The solution of the partial differential equation is made with a finite difference method coupled to optimization techniques of Differential Evolution (DE) and Particle Swarm Optimization (PSO) used in inverse problem. Statistical analysis shows no significant differences between reported and estimated curves, and no remarkable differences between results obtained using DE and PSO… More >

Yuta Kitamura¹, Noriyuki Miyazaki¹, Takahito Kumazaki², Naoto Nagakura³, Yasuhiro Hashimoto³, Isao Masada³

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.2, pp. 151-166, 2010, DOI:10.3970/cmes.2010.068.151

Abstract CaF₂ single crystal is used as high performance optical elements. We developed an analysis system for simulating birefringence of CaF₂ single crystal used as a chamber window of a gas laser light source. The analysis system consists of a stress analysis and a birefringence analysis. In the stress analysis, the finite element method was applied to obtain the mechanical stress caused by a window holder and gas pressure. In the birefringence analysis, the photo-elastic effect gives the change of refractive indices, from which the optical path difference and the fast axis are calculated by using the average stress method. The… More >