共查询到20条相似文献,搜索用时 31 毫秒
1.
《International Journal of Solids and Structures》2006,43(7-8):1991-2013
Wave propagation in a porous elastic medium saturated by two immiscible fluids is investigated. It is shown that there exist three dilatational waves and one transverse wave propagating with different velocities. It is found that the velocities of all the three longitudinal waves are influenced by the capillary pressure, while the velocity of transverse wave does not at all. The problem of reflection and refraction phenomena due to longitudinal and transverse wave incident obliquely at a plane interface between uniform elastic solid half-space and porous elastic half-space saturated by two immiscible fluids has been analyzed. The amplitude ratios of various reflected and refracted waves are found to be continuous functions of the angle of incidence. Expression of energy ratios of various reflected and refracted waves are derived in closed form. The amplitude ratios and energy ratios have been computed numerically for a particular model and the results obtained are depicted graphically. It is verified that during transmission there is no dissipation of energy at the interface. Some particular cases have also been reduced from the present formulation. 相似文献
2.
《Wave Motion》2020
In the present study, inhomogeneous plane harmonic waves propagation in dissipative partially saturated soils are investigated. The analytical model for the dissipative partially saturated soils is solved in terms of Christoffel equations. These Christoffel equations yields the existence of four wave (three longitudinal and one shear) modes in partially saturated soils. Christoffel equations are further solved to determine the complex velocities and polarizations of four wave modes. Inhomogeneous propagation is considered through a particular specification of complex slowness vector. A finite non-dimensional inhomogeneity parameter is considered to represent the inhomogeneous nature of these four waves. Impact of tortuosity parameter on the movement of pore fluids is considered. Hence, the considered model is capable of describing the wave behavior at high as well as mid and low frequencies. Numerical example is considered to study the effects of inhomogeneity parameter, saturation of water, porosity, permeability, viscosity of fluid phase and wave frequency on the velocity and attenuation of four waves. It is observed that all the waves are dispersive in nature (i.e., frequency dependent). 相似文献
3.
The propagation of elastic stress waves in a conical shell subjected to axial impulsive loading is studied in this paper by
means of the finite element calculation and model experiments. It is shown that there are two axisymmetrical elastic stress
waves propagating with different velocities, i.e., the longitudinal wave and the bending wave. The attenuation of these waves
while propagating along the shell surface is discussed. It is found in experiments that the bending wave is also generated
when a longitudinal wave reflects from the fixed end of the shell, and both reflected waves will separate during the propagation
due to their different velocities.
Southwest Institute of Structural Mechanics 相似文献
4.
This research addresses the investigation of an elastic wave field in a homogeneous and isotropic porous medium which is fully
saturated by a Newtonian viscous fluid. A new methodology is developed for describing the wave field in the medium excited
by multiple energy sources. To quantify the relative displacements between the fluid and solid of the medium, the governing
equations of the elastic wave propagation are derived in the form of displacements specially. The velocities and attenuation
of the waves are considered as functions of viscosity and frequency. Making use of the Hankel function and the moving-coordinate
method, a model of the wave motion with multiple cylindrical wave sources is built. Making use of the model established in
this research, the relative displacement between the fluid and the solid can be quantified, and the wave field in the porous
media can then be determined with the given energy sources. Numerical simulations of cylindrical waves from multiple energy
sources propagating in the porous medium saturated by viscous fluid are performed for demonstrating the practicability of
the model developed. 相似文献
5.
The features of propagation of longitudinal and transverse waves (LW and TW) in fractured porous medium (FPM) saturated with liquid are investigated by methods of multiphase mechanics. The mathematical model of FPM accounting for inequality of velocities and pressures of liquid in pores and fractures, liquid mass exchange and nonstationary interaction forces is developed. Processes of monochromatic wave propagation are studied. The dispersion relation is obtained and the effect of model parameters on wave propagation is analysed. It is established that one transverse and three longitudinal waves propagate in FPM saturated with liquid. The fastest LW is a deformational wave and the two others are filtrational. Filtrational waves attenuate much stronger than deformational and transverse waves. Distinction of velocities and pressures in liquid in various pore systems provides an explanation for the existence of the two filtrational waves in porous medium with two different characteristic sizes of pores. 相似文献
6.
Bettina Albers 《Transport in Porous Media》2011,86(2):537-557
Due to its propitious material properties sandstone is the most studied porous medium for the investigation of linear wave
propagation. However, in practical applications the behavior of other soil types, i.e., especially the three main soil types
sand, silt, and clay, are much more important. Therefore, the model for partially saturated soils introduced by Albers (Habilitation
Thesis, 2010a) is applied to 11 soil types classified in the German standard DIN 4220 to obtain information on the phase velocities
and attenuations of the three longitudinal waves and the shear wave appearing in such media. 相似文献
7.
《International Journal of Solids and Structures》2007,44(11-12):3638-3645
Two-dimensional plane wave propagation in an orthotropic micropolar elastic solid is studied. There exist three types of coupled waves in xy-plane, whose velocities depend upon the angle of propagation and material parameters. A problem on reflection of these plane waves from a stress-free boundary is considered. The reflection coefficients of various reflected waves are computed numerically for a particular model of the solid. The effects of anisotropy upon the velocities and reflection coefficients are depicted graphically for different angles of propagation. 相似文献
8.
This paper utilized anisotropic wave propagation theory to measure the elastic constants of a unidirectional fiber-reinforced
composite specimen. For plane waves propagating in the composite specimen, the deviation of the propagational directions between
the energy and phase velocities were measured. It is found that in such a sample, the deviations may be as large as 60 degrees.
The measured energy velocities were transformed to the phase velocities of the plane waves by employing a numerical scheme.
It is demonstrated that the elastic constants of a unidirectional fiber-reinforced composite can be determined by conducting
ultrasonic experiments in two principal symmetry planes. 相似文献
9.
Weiyun Chen Tangdai Xia Wentao Hu 《International Journal of Solids and Structures》2011,48(16-17):2402-2412
The mixture theory is employed to the analysis of surface-wave propagation in a porous medium saturated by two compressible and viscous fluids (liquid and gas). A linear isothermal dynamic model is implemented which takes into account the interaction between the pore fluids and the solid phase of the porous material through viscous dissipation. In such unsaturated cases, the dispersion equations of Rayleigh and Love waves are derived respectively. Two situations for the Love waves are discussed in detail: (a) an elastic layer lying over an unsaturated porous half-space and (b) an unsaturated porous layer lying over an elastic half-space. The wave analysis indicates that, to the three compressional waves discovered in the unsaturated porous medium, there also correspond three Rayleigh wave modes (R1, R2, and R3 waves) propagating along its free surface. The numerical results demonstrate a significant dependence of wave velocities and attenuation coefficients of the Rayleigh and Love waves on the saturation degree, excitation frequency and intrinsic permeability. The cut-off frequency of the high order mode of Love waves is also found to be dependent on the saturation degree. 相似文献
10.
《International Journal of Solids and Structures》1999,36(23):3469-3482
Dispersion of Stoneley waves is studied in a sedimentary layer of ocean bottom resting over basaltic solid half space. Sedimentary layer is assumed a transversely isotropic poroelastic medium. Lower-most solid half-space is assumed to be embedded with vertically aligned saturated micro-cracks and behaves transversely isotropic to wave propagation.Frequency equation is obtained in the form of determinantal equation. Role of phase angle is eliminated by expressing slowness of waves in terms of phase velocity and elastic constants. Numerical solutions for phase velocity and group velocity are obtained for a particular model. Calculations are made for different depths of ocean and sediments. Effect of thickness and density of cracks on these velocities are observed.Special cases are discussed which represent the absence of ocean and sediments, in the model considered. Changes in dispersion are discussed during the stress accumulation in an earthquake preparation region. 相似文献
11.
Features of the propagation of longitudinal and transverse plane waves along the layers of nanocomposites with process-induced
initial stresses are studied. The composite has a periodic structure: it is made by repeating two highly dissimilar layers.
The layers exhibit nonlinear elastic behavior in the range of loads under consideration. A Murnaghan-type elastic potential
dependent on the three invariants of the strain tensor is used to describe the mechanical behavior of the composite constituents.
To simulate the propagation of waves, finite-strain theory is used for developing a problem statement within the framework
of the three-dimensional linearized theory of elasticity assuming finite initial strains. The dependence of the relative velocities
of longitudinal and transverse waves on two components of small initial stresses in each layer and on the volume fraction
of the constituents is studied. It is established that there are thickness ratios of layers in some nanocomposites such that
the wave velocities are independent of the initial stresses and equal to the respective wave velocities in composites without
initial stresses
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Translated from Prikladnaya Mekhanika, Vol. 43, No. 4, pp. 3–26, April 2007. 相似文献
12.
Elastic characteristics and propagation velocities of ultrasonic waves in a TiC–TiNi composite material are determined by the ultrasonic resonance method. The values of the elastic moduli of the solid composite obtained are used to estimate its plastic properties. The effect of various additives on the elastic and plastic properties of the composite is studied. 相似文献
13.
Ya. Ya. Rushchitskii 《International Applied Mechanics》2001,37(1):107-113
The energy characteristics of waves propagating in composites are discussed. To describe the deformation of materials, two models are used — the classical model of an elastic body and the microstructural model of a two-phase elastic mixture. Both models take into account the quadratic nonlinearity of deformation based on the Murnaghan elastic potential. Analytical expressions for the velocity at which the energy of travelling plane longitudinal waves propagates are derived. It is shown that the nonlinearity of composite deformation decreases the velocities of energy propagation of both nondispersive and dispersive waves 相似文献
14.
J. J. Rushchitsky 《International Applied Mechanics》2005,41(11):1288-1298
General principles are formulated for modeling the elastic deformation of materials and analyzing plane waves in nonlinearly
elastic materials such as hyperelastic, hypoelastic, and those governed by the general law of elasticity. The results of studying
the propagation of plane waves in hypoelastic materials are further outlined. The influence of initial stresses and initial
velocities on the types and number of plane waves is studied. Wave effects characteristic of hypoelastic materials are predicted
theoretically. One of such effects is blocking of certain types of plane waves by initial stresses
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Translated from Prikladnaya Mekhanika, Vol. 41, No. 11, pp. 96–107, November 2005. 相似文献
15.
《Wave Motion》2018
In this paper, the propagation of Rayleigh waves in orthotropic non-viscous fluid-saturated porous half-spaces with sealed surface-pores and with impervious surface is investigated. The main aim of the investigation is to derive explicit secular equations and based on them to examine the effect of the material parameters and the boundary conditions on the propagation of Rayleigh waves. By employing the method of polarization vector the explicit secular equations have been derived. These equations recover the ones corresponding to Rayleigh waves propagating in purely elastic half-spaces. It is shown from numerical examples that the Rayleigh wave velocity depends strongly on the porosity, the elastic constants, the anisotropy, the boundary conditions and it differs considerably from the one corresponding to purely elastic half-spaces. Remarkably, in the fluid saturated porous half-spaces, Rayleigh waves may travel with a larger velocity than that of the shear wave, a fact that is impossible for the purely elastic half-spaces. 相似文献
16.
N. V. Chertova 《Journal of Applied Mechanics and Technical Physics》2008,49(6):1047-1054
The propagation of plane harmonic waves in viscoelastic and elastoviscoplastic materials are studied using the equations of
the field theory of defects, the kinematic identities for an elastic continuum with defects, and the dynamic equations of
gauge theory. Wave propagation velocities and refraction and absorption coefficients are determined. The structure of the
waves and the correlation between the displacement waves and the defect-field waves determining plastic deformation are analyzed.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 190–197, November–December, 2008. 相似文献
17.
The propagation of elastic waves is studied in a porous solid saturated with two immiscible viscous fluids.The propagation of three longitudinal waves is represented through three scalar potential functions.The lone transverse wave is presented by a vector potential function.The displacements of particles in different phases of the aggregate are defined in terms of these potential functions.It is shown that there exist three longitudinal waves and one transverse wave.The phenomena of reflection and refraction due to longitudinal and transverse waves at a plane interface between an elastic solid half-space and a porous solid half-space saturated with two immiscible viscous fluids are investigated.For the presence of viscosity in pore-fluids,the waves refracted to the porous medium attenuate in the direction normal to the interface.The ratios of the amplitudes of the reflected and refracted waves to that of the incident wave are calculated as a nonsingular system of linear algebraic equations.These amplitude ratios are used to further calculate the shares of different scattered waves in the energy of the incident wave.The modulus of the amplitude and the energy ratios with the angle of incidence are computed for a particular numerical model.The conservation of the energy across the interface is verified.The effects of variations in non-wet saturation of pores and frequencies on the energy partition are depicted graphically and discussed. 相似文献
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