A. Tadeu¹, L. Godinho¹, J. António¹, P. Amado Mendes¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.3, pp. 163-168, 2007, DOI:10.3970/icces.2007.003.163

Abstract This paper evaluates the 3D wave propagation in an elastic slab containing cracks whose geometry does not change along the direction parallel to the formation surfaces. Two different formulations are used and compared: the Traction Boundary Element Method (TBEM) and the Method of Fundamental Solutions (MFS). Both approaches are developed in the frequency domain and surmount the thin-body difficulty posed by the classical Boundary Element Method (BEM). The TBEM models the crack as a single line. The resulting hypersingular integrals are evaluated analytically. For the MFS, the solution is approximated in terms of a linear combination of fundamental solutions, generated… More >

J. António¹ , A. Tadeu¹, L. Godinho

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.3, pp. 157-162, 2007, DOI:10.3970/icces.2007.003.157

Abstract A frequency dependent formulation based on the Method of Fundamental Solutions (MFS) is used to simulate the sound wave propagation in a 3D acoustic space. This solution is approximated by a linear combination of fundamental solutions generated by virtual sources placed outside the domain in order to avoid singularities. The coating materials can be assumed to be absorbent. This is achieved in the model prescribing the impedance that is defined as a function of the absorption coefficient. The model is first verified against analytical solutions, provided by the image source technique for a parallelepiped room bounded by rigid walls. The… More >

T. Furumura¹, L. Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.2, pp. 153-168, 2004, DOI:10.3970/cmes.2004.006.153

Abstract Recent developments of the Earth Simulator, a high-performance parallel computer, has made it possible to realize realistic 3D simulations of seismic wave propagations on a regional scale including higher frequencies. Paralleling this development, the deployment of dense networks of strong ground motion instruments in Japan (K-NET and KiK-net) has now made it possible to directly visualize regional seismic wave propagation during large earthquakes. Our group has developed an efficient parallel finite difference method (FDM) code for modeling the seismic wavefield and a 3D visualization technique, both suitable for implementation on the Earth Simulator. Large-scale 3D simulations of seismic wave propagation… More >

S. Kucukcoban¹, L.F. Kallivokas²

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.2, pp. 109-146, 2010, DOI:10.3970/cmes.2010.064.109

Abstract We are concerned with elastic wave simulations arising in elastic, semi-infinite, heterogeneous, three-dimensional media with a vertical axis of symmetry through the coordinate origin. Specifically, we discuss the development of a new mixed displacement-stress formulation in PML-truncated axisymmetric media for forward elastic wave simulations. Typically, a perfectly-matched-layer (PML) is used to surround a truncated finite computational domain in order to attenuate outwardly propagating waves without reflections for all non-zero angles-of-incidence and frequencies. To date, standard formulations use split fields, where the displacement components are split into normal and parallel to the PML interface components. In this work, we favor unsplit… More >

S.D. Akbarov^1,2

CMC-Computers, Materials & Continua, Vol.32, No.1, pp. 29-60, 2012, DOI:10.3970/cmc.2012.032.029

Abstract By the use of the Murnaghan potential the influence of third order elastic constants on axisymmetric longitudinal wave propagation velocity in a pre-stressed two-layered circular hollow cylinder is investigated. This investigation is carried out within the scope of the piecewise homogeneous body model by utilizing the first version of the small initial deformation theory of the Three-dimensional Linearized Theory of Elastic Waves in Initially Stressed Bodies. Numerical results are obtained and analyzed for the cases where the material of the outer hollow cylinder material is aluminum, but the material of the inner cylinder is steel (Case 1) and tungsten (Case… More >

Chien-Ching Ma^1,2, Yi-Hsien Lin², Shih-Hao Lin²

CMC-Computers, Materials & Continua, Vol.31, No.1, pp. 37-64, 2012, DOI:10.3970/cmc.2012.031.037

Abstract In this article, the transient response in a functionally graded material (FGM) slab is analyzed by Laplace transform technique. The numerical Laplace inversion (Durbin's formula) is used to calculate the dynamic behavior of the FGM slab. The slab is subjected an uniform loading at the upper surface, and the lower surface are assumed to be traction-free or fixed conditions. The analytical solutions are presented in the transform domain and the numerical Laplace inversion is performed to obtain the transient response in time domain. To take the accuracy and computational efficiency in consideration, Durbin's method is suitable for calculating the long-time… More >

Jiun-Yu Wu^1,2, Hui-Ching Wang¹, Ming-I Char¹, Bo-Chen Tai¹

CMC-Computers, Materials & Continua, Vol.28, No.3, pp. 261-280, 2012, DOI:10.3970/cmc.2012.028.261

Abstract In this paper, we use the Local adaptive differential quadrature method (La-DQM) to solve multi-dimensional inverse scattering problem (ISP) of wave propagation. The La-DQM uses fictitious points to tackle the high-order differential equations with multi-boundary conditions and numerical results can be obtain directly in the calculation process. Six examples show the effectiveness and accuracy of the La-DQM in providing excellent estimates of unknown wave propagation from the given data. We think that the scheme is applicable to the ISP of wave propagation. Numerical results show that the La-DQM is powerful method for solving the inverse scattering problem of wave propagation. More >

Surkay D. Akbarov^1,2, Tamer Kepceler¹, M. Mert Egilmez¹, Ferhat Dikmen¹

CMC-Computers, Materials & Continua, Vol.26, No.2, pp. 91-110, 2011, DOI:10.3970/cmc.2011.026.091

Abstract This paper studies the torsional wave dispersion in the hollow bi-material compounded cylinder with finite initial strains. The investigations are carried out within the scope of the piecewise homogeneous body model with the use of the three-dimensional linearized theory of elastic waves in initially stressed bodies. The mechanical relations of the materials of the cylinders are described through the harmonic potential. The numerical results on the influence of the initial stretching or compression of the cylinders along the torsional wave propagation direction are presented and discussed More >

Liu Liqi¹, Wang Haitao^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.109-110, No.4, pp. 303-324, 2015, DOI:10.3970/cmes.2015.109.303

Abstract This paper presents a three-dimensional (3-D) boundary element method (BEM) scheme based on the Radial Integration Method (RIM) for wave propagation analysis of continuously non-homogeneous problems. The Kelvin fundamental solutions are adopted to derive the boundary-domain integral equation (BDIE). The RIM proposed by Gao (Engineering Analysis with Boundary Elements 2002; 26(10):905-916) is implemented to treat the domain integrals in the BDIE so that only boundary discretization is required. After boundary discretization, a set of second-order ordinary differential equations with respect to time variable are derived, which are solved using the Wilson-q method. Main advantages of the proposed method are that… More >

Mohammad Hossein Ghadiri Rad¹, Farzad Shahabian^1,2, Seyed Mahmoud Hosseini³

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.3, pp. 135-157, 2015, DOI:10.3970/cmes.2015.108.135

Abstract A meshless method based on the local Petrov-Galerkin approach is developed for elasto-dynamic analysis of geometrically nonlinear two dimensional (2D) problems in hyper-elastic functionally graded materials. The radial point interpolation method (RPIM) is utilized to build the shape functions and the Heaviside step function is used as the test function. The mechanical properties of functionally graded material are considered to continuously vary in a certain direction and are simulated using a nonlinear power function in volume fraction form. Considering the large deformations, it is assumed that the domain be made of large deformable neo-Hookean hyperelastic materials. Rayleigh damping is employed… More >