Propagation Characteristics of Rayleigh Waves in a Partially Saturated Ground

2006 ◽  
Author(s):  
Xinmin Zhou ◽  
Tangdai Xia
Keyword(s):  
Rayleigh Waves ◽  
Propagation Characteristics ◽  
Partially Saturated

Analysis of dispersion curves of Rayleigh waves in the frequency–wavenumber domain

2004 ◽  
Vol 41 (4) ◽  
pp. 583-598 ◽  
Author(s):  
Laiyu Lu ◽  
Bixing Zhang
Keyword(s):  
Numerical Simulation ◽  
Surface Waves ◽  
Key Words ◽  
Relative Error ◽  
Spectrum Analysis ◽  
Rayleigh Waves ◽  
Dispersion Curves ◽  
Propagation Characteristics ◽  
Wavenumber Domain ◽  
Analysis Of Dispersion

The method of spectrum analysis of surface waves (SASW) is discussed briefly. The analysis of the dispersion curves of Rayleigh waves in the frequency–wavenumber (f–k) domain is suggested due to the problems encountered in SASW. Three models of the layered media are considered according to typical situations in practice. All the modes that can be effectively excited are analyzed. The excitation and propagation characteristics of the Rayleigh waves are investigated by numerical simulation. The effects of some parameters such as number of channels and distance (s) between the source and the first receiver on the dispersion curves are investigated in detail for three models. Some important results about the number of receiver channels, relative error, mode jumping, and other aspects are obtained. It is found that reliable dispersion curves can be obtained by f–k analyses when the distance between the first receiver and the source is greater than one half the wavelength (0.5λ).Key words: dispersion curves, Rayleigh waves, SASW, frequency–wavenumber domain, mode jumping.

Characteristics of Laser-Generated Visco-Elastic Rayleigh Waves

2013 ◽  
Vol 543 ◽  
pp. 22-25
Author(s):  
Qing Bang Han ◽  
Jian Li ◽  
Hao Wang ◽  
Chang Ping Zhu
Keyword(s):  
Elastic Modulus ◽  
Transient Response ◽  
Rayleigh Waves ◽  
Laser Ultrasonics ◽  
Normal Displacement ◽  
Space Structures ◽  
Propagation Characteristics ◽  
Elastic Parameters ◽  
Kelvin Model ◽  
Dispersion And Attenuation

This paper reports on a study of the propagation characteristics of visco-elastic, Rayleigh waves induced by laser ultrasonics in half space structures. Beginning with the Kelvin model, the characterization equation and the normal displacement of visco-elastic Rayleigh waves in are derived and the influence of the visco-elastic modulus on dispersion and attenuation are discussed. The transient response of a visco-elastic Rayleigh wave is also simulated by means of Laplace and Hankel inversion transforms. The papers results and conclusions will provide insights and guidance for estimating visco-elastic parameters

scholarly journals Complex Rayleigh Waves in Nonhomogeneous Magneto-Electro-Elastic Half-Spaces

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1011
Author(s):  
Ke Li ◽  
Shuangxi Jing ◽  
Jiangong Yu ◽  
Bo Zhang
Keyword(s):  
Rayleigh Waves ◽  
Constitutive Relations ◽  
Three Dimensional ◽  
Energy Conversion Efficiency ◽  
Propagation Characteristics ◽  
Improved Method ◽  
Acoustic Surface Wave ◽  
Phase Velocities ◽  
Calculation Process ◽  
Wave Modes

The complex Rayleigh waves play an important role in the energy conversion efficiency of magneto-electro-elastic devices, so it is necessary to explore the wave propagation characteristics for the better applications in engineering. This paper modifies the Laguerre orthogonal polynomial to investigate the complex Rayleigh waves propagating in nonhomogeneous magneto-electro-elastic half-spaces. The improved method simplifies the calculation process by incorporating boundary conditions into the constitutive relations, shortens the solving time by transforming the solution of wave equation to an eigenvalue problem, and obtains all wave modes, including real and imaginary and complex wavenumbers. The three-dimensional curves of full frequency spectrum and phase velocities are presented for the better description of the conversion from complex Rayleigh wave modes to real wave ones; besides, the displacement distributions, electric and magnetic potential curves are obtained in thickness and propagation directions, respectively. Numerical results are analyzed and discussed elaborately in three cases: variation of nonhomogeneous coefficients, absence of magnetism, and absence of electricity. The results can be used to optimize and fabricate the acoustic surface wave devices of the nonhomogeneous magneto-electro-elastic materials.

Environmental microscopy of capillary stress-induced strain behavior in ambient-pressure aerogels

1996 ◽  
Vol 54 ◽  
pp. 850-851
Author(s):  
Sudeep M. Rao ◽  
Joshua Samuel ◽  
Sai S. Prakash ◽  
C. Jeffrey Brinker
Keyword(s):  
Silica Aerogel ◽  
Ambient Pressure ◽  
Drying Shrinkage ◽  
Pore Filling ◽  
Silica Network ◽  
Strain Behavior ◽  
Partially Saturated ◽  
Capillary Stress ◽  
Wetting Liquid ◽  
Aerogel Films

Ambient pressure silica aerogel thin films have recently been prepared by exploiting reversible drying shrinkage caused by derivatization of the internal gel surface. Aerogels have porosities of upto 99.9% and due to the small size of the pores (few nanometers), large capillary stresses are produced in gels that are partially saturated with a wetting liquid. As a result of these capillary stresses, the flexible silica network undergoes strain which has been observed using environmental microscopy. This technique allows variation of the equilibrium vapor pressure and temperature, and a simultaneous monitoring of the deformation of the unconstrained film thickness. We have observed >600% deformation during the pore-filling and pore-emptying cycles. In this presentation, we discuss the unique stress-strain behavior of these films.Ref.: Sai S. Prakash, C. Jeffrey Brinker, Alan J. Hurd & Sudeep M. Rao, "Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage", Nature. Vol. 374, 30 March, 1995, 439-443.

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