J. Cugnoni¹, M. Galli²

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.2, pp. 165-186, 2010, DOI:10.3970/cmes.2010.066.165

Abstract With the progress of miniaturization, in many modern applications the characteristic dimensions of the physical volume occupied by particle-reinforced composites are getting comparable with the reinforcement size and many of those composite materials undergo plastic deformations. In both experimental and modelling contexts, it is therefore very important to know whether, and up to which characteristic size, the description of the composites in terms of effective, homogenized properties is sufficiently accurate to represent their response in the actual geometry. Herein, the case of particle-reinforced composites with elastoviscoplastic matrix materials and polyhedral randomly arranged linear elastic reinforcement… More >

Zhiming Gao², Yichen Ma³

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.2, pp. 135-164, 2010, DOI:10.3970/cmes.2010.066.135

Abstract Shape optimization technique has an increasing role in fluid dynamics problems governed by distributed parameter systems. In this paper, we present the problem of shape optimization of two dimensional viscous flow governed by the time dependent Navier-Stokes equations. The minimization problem of the viscous dissipated energy was established in the fluid domain. We derive the structure of continuous shape gradient of the cost functional by using the differentiability of a saddle point formulation with a function space parametrization technique. Finally a gradient type algorithm with mesh adaptation and mesh movement strategies is successfully and efficiently More >

P. Bettini¹, M. Midrio², R. Specogna²

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.2, pp. 117-134, 2010, DOI:10.3970/cmes.2010.066.117

Abstract In this paper we propose a geometric formulation to solve 3D electromagnetic wave problems in unbounded regions in the frequency domain. An absorbing boundary condition (ABC) is introduced to limit the size of the computational domain by means of anisotropic Perfectly Matched Layers (PML) absorbing media in the outer layers of an unstructured mesh. The numerical results of 3D benchmark problems are presented and the effect of the PML parameters and scaling functions on PML effectiveness are discussed. More >

Xue-Qian Fang¹, Jin-Xi Liu¹, Ming-Zhang Chen¹, Li-Yong Fu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.2, pp. 101-116, 2010, DOI:10.3970/cmes.2010.066.101

Abstract In the authors' previous work (Zhang et al., 2010), the dynamic stress resulting from two cavities in exponential functional graded materials subjected to non-homogeneous shear waves has been studied. In this paper, the wave function expansion method is further developed to the case of two cylindrical inclusions embedded in functional graded materials, and the incident angle is also considered. The multiple scattering and refraction of non-homogeneous shear waves around the two inclusions are described accurately. The dynamic stress concentration factors around the two inclusions are presented analytically and numerically. The multiple effects of geometrical and More >

D. C. C. Lam¹, L-H Keung¹, P. Tong²

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.1, pp. 73-100, 2010, DOI:10.3970/cmes.2010.066.073

Abstract Additional molecular rotations in long chained macromolecules lead to additional size dependence. In this investigation, we developed the higher order viscoelasticity framework and conducted experiments to determine the higher order material length scale parameters needed to describe the higher order viscoelastic behavior in the new framework. In the first part of the investigation of high order deformation behavior of macromolecular solids, the higher-order viscoelasticity theories for Maxwell and Kelvin-Voigt materials, and models of higher-order viscoelastic beam deflection creep are developed in this study. We conducted creep bending experiments with epoxy beams to show that the… More >

C.H. Tsai¹, D.L. Young², J. Kolibal³

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.1, pp. 53-72, 2010, DOI:10.3970/cmes.2010.066.053

Abstract The time evolution method of fundamental solutions (MFS) is proposed to solve backward heat conduction problems (BHCPs). The time evolution MFS belongs to one of the mesh-free numerical methods and is essentially composed of a sequence of diffusion fundamental solutions which exactly satisfy the heat conduction equations. Through correct treatment of temporal evolution, the resulting system of the time evolution MFS is smaller, and effectively decreases the possibility of ill-conditioning induced by such strongly ill-posed problems. Both one-dimensional and two-dimensional BHCPs are examined in this study, and the numerical results demonstrate the accuracy and stability More >

Phong B.H. Le¹, Timon Rabczuk², Nam Mai-Duy¹, Thanh Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.1, pp. 25-52, 2010, DOI:10.3970/cmes.2010.066.025

Abstract A novel meshless method based on Radial Basis Function networks (RBFN) and variational principle (global weak form) is presented in this paper. In this method, the global integrated RBFN is localized and coupled with the moving least square method via the partition of unity concept. As a result, the system matrix is symmetric, sparse and banded. The trial and test functions satisfy the Kronecker-delta property, i.e. Φ_i(x_j) = δ_ij. Therefore, the essential boundary conditions are imposed in strong form as in the FEMs. Moreover, the proposed method is applicable to scattered nodes and arbitrary domains. The More >

Marcin Maździarz¹

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.1, pp. 1-24, 2010, DOI:10.3970/cmes.2010.066.001

Abstract The paper presents unified approach to 3D isoparametric Lagrange brick, tetra, and prism finite elements. All shape functions, linear, quadratic and cubic, are depicted in one Cartesian orthogonal coordinate system x,y,z regardless of the type of element. This allows one to use a single transformation rule to calculate global derivatives and a second for integration. Proper numerical Gauss quadratures for these isoparametric elements in a unified approach are presented additionally. More >

E. Carrera, S. Brischetto¹, M. Cinefra²

CMES-Computer Modeling in Engineering & Sciences, Vol.65, No.3, pp. 259-342, 2010, DOI:10.3970/cmes.2010.065.259

Abstract This paper investigates the problem of free vibrations of multilayered plates and shells embedding anisotropic and thickness polarized piezoelectric layers. Carrera's Unified Formulation (CUF) has been employed to implement a large variety of electro-mechanical plate/shell theories. So-called Equivalent Single Layer and Layer Wise variable descriptions are employed for mechanical and electrical variables;linear to fourth order expansions are used in the thickness direction z in terms of power of z or Legendre polynomials. Various forms are considered for the Principle of Virtual Displacements (PVD) and Reissner's Mixed Variational Theorem (RMVT) to derive consistent differential electro-mechanical governing… More >

Chen-Ming Kuo¹, Cheng-Hao Huang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.65, No.3, pp. 245-258, 2010, DOI:10.3970/cmes.2010.065.245

Abstract Vibrations induced by high-velocity train passing through environmental sensitive area are important issues to railway authorities. Research has been granted to resolve the environmental impact generated from vehicle-track interaction to the neighbor buildings. Models were established to simulate the vehicle-track interaction system which is the source of vibrations. Among them, Euler beam with finite length on elastic foundation subjected to moving loads is most commonly used to simulate the continuous track on site. The reason of modeling infinite length track with finite length model is to make solving possible by numerical analysis. However, the accuracy… More >