Jun Liu¹, Mauro Ferrari¹

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 421-430, 2003, DOI:10.3970/cmes.2003.004.421

Abstract A microstructure-accounting mechanical field theory approach is applied to the problem of reflection from a granular thin layer embedded between two solid substrates to study the direct relationship of the micro-structural parameters and the overall reflection coefficients of the thin layer. The exact solution for plane wave reflection coefficients is derived under the new theoretical framework giving quantitative relations between the macroscopic reflection coefficients and a set of micro structural/physical parameters including particle size and micromoduli. The model was analyzed using averaged material properties of biological tissue for the granular thin layer. It was demonstrated that changes in micro-level physical… More >

Mira Mitra¹, S. Gopalakrishnan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 49-68, 2006, DOI:10.3970/cmes.2006.015.049

Abstract In this paper, a 2-D Wavelet based Spectral Finite Element (WSFE) is developed and is used to study wave propagation in an isotropic plate. Here, first, wavelet approximation is done in both temporal and one spatial (lateral) dimension to reduce the governing partial differential wave equations to a set of Ordinary Differential Equations (ODEs). Daubechies compactly supported orthogonal scaling functions are used as basis which allows finite domain analysis and easy imposition of initial/boundary conditions. However, the assignment of initial and boundary conditions in time and space respectively, are done following two different methods. Next, the reduced ODEs are solved… More >

J.T. Verbis¹, S.V. Tsinopoulos², D. Polyzos²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 803-814, 2002, DOI:10.3970/cmes.2002.003.803

Abstract In the present work the iterative effective medium approximation (IEMA) is appropriately used for wave dispersion and attenuation predictions in fiber-reinforced composites that microscopically exhibit a non-uniform fiber distribution. Two types of composites with such irregular topology of fibers are considered. The first contains a regular distribution of clusters of fibers embedded in a composite matrix with uniformly distributed fibers, and the second a uniform distribution of matrix-rich inclusions embedded in a fiber-rich regular composite medium. The resulting from the application of the IEMA scattering problems are solved numerically by means of a two dimensional boundary element method. The obtained… More >

A. Aimi¹, M. Diligenti¹, S. Panizzi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.58, No.2, pp. 185-220, 2010, DOI:10.3970/cmes.2010.058.185

Abstract In this paper we consider 2D wave propagation Neumann exterior problems reformulated in terms of a hypersingular boundary integral equation with retarded potential. Starting from a natural energy identity satisfied by the solution of the differential problem, the related integral equation is set in a suitable space-time weak form. Then, a theoretical analysis of the introduced formulation is proposed, pointing out the novelties with respect to existing literature results. At last, various numerical simulations will be presented and discussed, showing accuracy and stability of the space-time Galerkin boundary element method applied to the energetic weak problem. More >

Takahide Nakamura

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 115-116, 2011, DOI:10.3970/icces.2011.019.115

Abstract No limitation exists virtually in target size for the classical simulation of atoms with the O(N) algorithms on parallel machines. On the other hand, the time step cannot be changed and hence the total simulation time still remains short. It is meaningful to increase the time step by the coarse-graining the atomic system. The coarse-grained particle (CGP) method has been proposed for such purposes, but it is applicable only to crystalline solids at zero-temperature limit [1,2]. The total energy of the CGP system is defined as the statistical ensemble average of the atomistic Hamiltonian under some certain constraint. For analytic… More >

Weiqiu CHEN

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.4, pp. 125-126, 2011, DOI:10.3970/icces.2011.018.125

Abstract We will report a theory of surface piezoelectricity which governs a plane surface of a piezoelectric body. The piezoelectric surface may be endowed with different properties from the bulk material, and can account for the well-known surface effect which becomes increasingly important in micro- or nano-sized structures. In this study, the surface is treated as a piezoelectric thin layer of thickness h, and the state-space formulism is adopted to obtain the transfer relation between the state vectors at the top and bottom surfaces of the layer. The power series of the transfer matrix is then used, which can be truncated… More >

Lifeng Wang, Haiyan Hu, Wanlin Guo

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.1, pp. 15-16, 2011, DOI:10.3970/icces.2011.020.015

Abstract The wave dispersions of longitudinal and flexural wave propagations in single-walled and multi-walled carbon nanotubes are studied in the frame of continuum mechanics and molecular dynamics simulation. The dispersion relations between the phase velocity, group velocity and the wave number for the flexural and longitudinal waves, described by a beam model and a cylindrical shell model, are established for both single- and multi-walled carbon nanotubes. The effect of micro-structures in carbon nanotubes on the wave dispersion is revealed through the non-local elastic models of beam and cylindrical shell including the second order gradient of strain and a parameter of micro-structure.… More >

Wei Cai^*, Hua Chen

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.4, pp. 80-80, 2019, DOI:10.32604/icces.2019.05672

Abstract Recent decades have witnessed a fast growing research on the theory of wave propagation in granular materials because of its important applications of frequency dependent attenuation. Fractional calculus has been recognized as an efficient tool to model such kind of phenomena. This study firstly presented a survey of the frequency-dependent attenuated fractional wave models. To have a better understanding of the wave propagation in layered materials, the variable-order fractional wave equation is subsequently proposed on the basis of the corresponding viscoelastic constitutive equation. Numerical simulations compared with traditional models are presented by the implicit finite difference method to the efficiency… More >

D. I. Fotiadis¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.5, No.2, pp. 85-92, 2008, DOI:10.3970/icces.2008.005.085

Abstract Quantitative ultrasound has attracted significant interest in the evaluation of bone fracture healing. Animal and clinical studies have demonstrated that the propagation velocity across fractured bones can be used as an indicator of healing. Researchers have recently employed computational methods for modeling wave propagation in bones aiming to gain insight into the underlying mechanisms of wave propagation and to further enhance the monitoring capabilities of ultrasound. In this paper we review the computational studies of ultrasound wave propagation in intact and healing bones. More >

K. Inaba¹, M. Yamamoto², J.E. Shepherd³, A. Matsuo⁴

The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.1, pp. 41-46, 2007, DOI:10.3970/icces.2007.004.041

Abstract The purpose of this research is to explore an explanation of detonation soot track formation, comparing with previous hypothesis of formation mechanism. Focusing on the role of shear stress in transporting soot along the surface, we investigated the non-reactive Mach reflections numerically with three-dimensional compressible Navier-Stokes simulations. Numerical results are compared with a two-dimensional detonation simulation and used to investigate the effect of shear stress spatial and temporal variations on soot redistributions. The motions of soot due to surface shear stress are numerically examined with treating soot as particles and fluid parcel. More >