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1
Content available Rayleigh wave propagation in isotropic sandy layer sliding over isotropic sandy semi-infinite medium with sliding contact
Madan Dinesh Kumar, Kumar Naveen, Rani Annu
International Journal of Applied Mechanics and Engineering
|
2023
|
Vol. 28, no. 1
58--70
EN
The present study aims to investigate Rayleigh wave propagation in an isotropic sandy layer overlying an isotropic sandy semi-infinite medium, with interface considered to be imperfect (slide contact and dislocation like model). Expressions for displacement components are obtained using the variable separation method. The dispersion frequency equation for the Rayleigh wave propagating in sandy media is derived using suitable boundary conditions. Particular cases, such as when the interface is in smooth contact and when sandy media are replaced by elastic media, are also discussed. Using MATLAB software, the effects of the imperfectness parameter (slide contact and dislocation like model) and sandy parameter on the Rayleigh waves’ phase velocity are investigated and compared with the already obtained results of the dislocation like model. The present study may find useful applications in geophysics, civil engineering and soil mechanics.
2
Content available remote Shear wave velocity structure beneath the eastern Indian Ocean from Rayleigh wave dispersion measurements
Rehman Haseeb, Sharma Jyoti, Subrahmanyam Mangalampalli, Begum Shaik Kareemunnisa
Acta Geophysica
|
2023
|
Vol. 71, no. 3
1187--1201
EN
The Eastern Indian Ocean is a tectonically and geodynamically active region that has experienced deformations due to rifting, uplifting, and plume activity. The earlier Rayleigh wave studies in the East Indian Ocean were mainly focused on the structure of the Bay of Bengal, Ninety East Ridge, and Broken Ridge. The structure of other region of the East Indian Ocean is not much explored. In the present study, Rayleigh wave dispersion analysis is performed to observe the signatures of upper mantle deformation in terms of shear wave velocity of the East Indian Ocean using global search method. The fundamental mode Rayleigh wave group velocities are estimated between 15 and 100 s using the multiple filter technique. The group velocities of the raypaths that traverse the same region are clustered (E1–E8) to get an average dispersion curve. Using a genetic algorithm, each cluster's group velocities are inverted for shear velocity structure. The observed dispersion curve of E6, E7, and E8 indicates the lower group velocities between 35 and 100 s relative to E1, E2, E3, E4, and E5, with an average variation of about 0.07–0.18 km/s. The crustal thickness obtained in the study region is ~ 26 km and is due to the increased thickness of the lower crust (9.1–12.4 km) having Vs 3.95–4.04 km/s. The theoretical Vs have been calculated for serpentinite rock at uppermost lithospheric conditions and found to be similar to the Vs of the lower crust in the present study. Hence, it is assumed that unusual crustal thickness is due to the progressive development of the upper lithosphere formation (Ultramafic rock) into material (serpentinite rock) with crustal-like shear velocity or moderately lower than sub-Moho shears velocity. The undeformed lithosphere is evidenced by the high-velocity (Vs 4.62–4.77 km/s) layer beneath the Moho, whose thickness ranges from 41.3 to 51.6 km. The high-velocity lithosphere is followed by a low-velocity zone that extends up to 160 km; however, the variation in Vs (4.57–4.31 km/s) indicates that the low-velocity zone is deformed.
3
Content available Moving semi-infinite mode-III crack inside the semi-infinite elastic media
Mandal Palas
Journal of Theoretical and Applied Mechanics
|
2020
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Vol. 58 nr 3
649--659
EN
The problem of a semi-infinite moving mode-III crack inside a semi-infinite isotropic half- -space is considered. The crack is located between a semi-infinite elastic medium and a layer whose distance from the surface to crack depth is h. Initially, Fourier transformation and inverse Fourier transformation are applied to transfer the governing boundary value problem to the well-known Wiener-Hopf equation. The purpose of this problem is to obtain the analytical solution of Stress Intensity Factor (SIF) and Crack Opening Displacement (COD) at the neighbourhood of the crack tip. In numerical Section, I have discussed the variation of parameters (crack velocity, layer distance h from the surface to crack depth) to show the effect of these parametric values on the graphs of SIF and COD where the material properties (density, shear modulus) were fixed.
4
Content available remote Mathematical study of Rayleigh waves in piezoelectric microstretch thermoelastic medium
Kumar Arvind, Abo-Dahab S. M., Ailawalia Praveen
Mechanics and Mechanical Engineering
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2019
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Vol. 23, nr 1
86--93
EN
This paper is concerned with the study of propagation of Rayleigh waves in a homogeneous isotropic piezo-electric microstretch-thermoelastic solid half-space. The medium is subjected to stress-free, isothermal boundary. After developing a mathematical model, the dispersion curve in the form of polynomial equation is obtained. Phase velocity and attenuation coefficient of the Rayleigh wave are computed numerically. The numerically simulated results are depicted graphically. Some special cases have also been derived from the present investigation.
5
Content available On propagation of Rayleigh type surface wave in five different theories of thermoelasticity
Singh B., Verma S.
International Journal of Applied Mechanics and Engineering
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2019
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Vol. 24, no. 3
661--673
EN
The governing equations for a homogeneous and isotropic thermoelastic medium are formulated in the context of coupled thermoelasticity, Lord and Shulman theory of generalized thermoelasticity with one relaxation time, Green and Lindsay theory of generalized thermoelasticity with two relaxation times, Green and Nagdhi theory of thermoelasticity without energy dissipation and Chandrasekharaiah and Tzou theory of thermoelasticity. These governing equations are solved to obtain general surface wave solutions. The particular solutions in a halfspace are obtained with the help of appropriate radiation conditions. The two types of boundaries at athe surface of a half-space are considered namely, the stress free thermally insulated boundary and stress free isothermal boundary. The particular solutions obtained in a half-space satisfy the relevant boundary conditions at the free surface of the half-space and a frequency equation for the Rayleigh wave speed is obtained for both thermally insulated and isothermal cases. The non-dimensional Rayleigh wave speed is computed for aluminium metal to observe the effects of frequency, thermal relaxation time and different theories of thermoelasticity.
6
Content available remote Propagation of Rayleigh wave in two-temperature dual-phase-lag thermoelasticity
Singh B., Kumari S., Singh J.
Mechanics and Mechanical Engineering
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2017
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Vol. 21, nr 1
105--116
EN
The governing equations of transversely isotropic dual-phase-lag two-temperature thermoelasticity are solved for the surface wave solutions. The particular solutions in the half-space satisfy the boundary conditions at a thermally insulated /isothermal stress-free surface of a half-space to obtain the frequency equation of the Rayleigh wave for the cases of coupled thermoelasticity, Lord and Shulman thermoelasticity and dual-phase-lag thermoelasticity. Some particular and special cases are obtained. The numerical values of the non-dimensional speed of the Rayleigh wave are computed and shown graphically against frequency, non-dimensional elastic constant and two-temperature parameter. The effects of frequency, two-temperature and dual-phase-lag are observed on the nondimensional speed of Rayleigh wave.
7
Content available Symulacja rozchodzenia się fali drganiowej od torowiska tramwajowego
Bednarz J., Brożek G., Targosz J.
Autobusy : technika, eksploatacja, systemy transportowe
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2017
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R. 18, nr 6
518--523, CD
PL
W artykule omówiony zostały badania symulacyjne rozchodzenia się fali drganiowej od wibroizolowanych i nie wibroizolowanych torowisk tramwajowych na przykładzie aglomeracji śląskiej. Opracowano model numeryczny podłoża i przeprowadzono symulację drgań w przypadku drgań torowiska wibroizolowanego oraz torowiska posadowionego na podłożu betonowym. Jako wejście do modelu numerycznego wykorzystano pomiary drgań wykonanych wcześniej. Przeprowadzono symulację i oszacowano wpływ oddziaływań dynamicznych na konstrukcję budynku znajdującego się w pobliżu torowisk i w oparciu o skale SWD oceniono stan zagrożenia konstrukcji. Symulacja potwierdziła że fala drganiowa w gruncie ma charakter fali Rayleigha.
EN
The article discusses simulation of vibration wave propagation in the ground for tram tracks viroisolated and nonvibroisolated on the example of the Silesian agglomeration. The numerical model of the ground was developed and the vibration simulation was performed in the case of vibration of the vibration rail track and the track laid on the concrete substrate. As a input to the numerical model, results of measurements of vibrations made earlier were used. The simulations were carried out and the impact of dynamic loads on the construction of a building near the track and on the basis of SWD scales was assessed. Simulation confirmed that the vibration wave in the ground is a Rayleigh wave type.
8
Content available remote Application of Multichannel Analysis of Surface Waves to S-Phase Wave Anisotropy Estimation
Stan-Kłeczek I., Mendecki M. J.
Acta Geophysica
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2016
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Vol. 64, no. 5
1593--1604
EN
The Multichannel Analysis of Surface Waves (MASW) is an increasingly used technique for recognition of a shallow geological structure and estimation of geotechnical parameters, e.g., S-wave velocity, layer density, layer thickness, shear modulus, estimated P-wave velocity, and estimated Poisson ratio. MASW surveys were carried out in two limestone quarries in the southern part of Poland. The experimental areas are characterised by a simple geological structure: consolidated Triassic limestone. Measurement profiles were arranged as a shapely six-pointed star. For each survey line, 12 geophones with 2-meter (Deposit 1) and 3-meter (Deposit 2) spacing were applied. The research allowed to compare P- and S-wave velocity changes with the main crack systems in the studied rock masses.
9
Content available Nonlinear surface elastic waves in materials
Rushchitsky J.
Vibrations in Physical Systems
|
2014
|
Vol. 26
33--40
EN
This paper is devoted to analysis of the surface nonlinear elastic harmonic waves of four types (Rayleigh and Stoneley harmonic waves within the framework of plane strain state; Love and Mozhaev harmonic wave within the framework of anti-plane strain state). The nonlinear model is based on introducing the Murnaghan elastic potential, which includes both geometrical and physical nonlinearities. Each type of surface waves is discussed in four steps: statement of the problem, nonlinear wave equations, approximate solution (first two approximations), so-me conclusions. A nonlinear analysis of waves required many novelties: new variants of the Murnaghan potential, new nonlinear wave equations and new nonlinear boundary conditions. The nonlinear wave equations were solved by the method of successive approximations. A new approach to analyze the boundary conditions is offered. Some new nonlinear wave effects are observed theoretically: a wave picture is reached by the 2nd harmonic and becomes changing in time of propagation, the wave numbers become depending on the initial amplitude.
10
Content available Przegląd zastosowania metody interferometrii sejsmicznej
Czarny R.
Przegląd Górniczy
|
2014
|
T. 70, nr 7
84--91
PL
Artykuł w sposób przeglądowy przedstawia szerokie możliwości zastosowania interferometrii sejsmicznej. Metoda jest stosunkowo nowa, mając na uwadze pierwsze eksperymenty wykonane w 2001 roku, i aktualnie znajduje się w fazie dynamicznego rozwoju. W pracy omówiono jej zastosowanie w wielu zagadnieniach związanych z odwzorowaniem budowy wnętrza Ziemi oraz warstw przypowierzchniowych, a także zagadnień geoinżynierskich z np. monitorowania czynnych osuwisk. Przedstawione przykłady badań zostały opublikowane w uznanych czasopismach naukowych.
EN
The aim of this paper is to review the wide range of seismic interferometry applications. Despite the fact that only 10 years have passed since the first application was implemented in seismology, seismic interferometry is currently used in many issues beginning with analysis of the Earth´s deep interior and ending with the time-laps velocity changes at active landslides. The presented research results were published in leading scientific journals.
11
Content available remote Rayleigh wave propagation: A case wise study in a layer over a half space under the effect of rigid boundary
Kumar Vishwakarma S., Gupta S.
Archives of Civil and Mechanical Engineering
|
2014
|
Vol. 14, no. 1
181--189
EN
In the present paper, case wise studies have been made to investigate the existence of Rayleigh surface wave in an earth's crustal layer. In the first case, the layer has been kept sandwiched between a rigid boundary plane and a sandy half space, while in the second case the sandy half space has been replaced by an elastic half space with void pores. The dispersion relation has been deduced in both the cases subjected to certain boundary conditions. The phase velocity has been calculated numerically and the effect of sandy parameter, rigid boundary, wave number, inhomogeneity parameter and void parameter on it has been illustrated and displayed by means of graphs. It has been found that the phase velocity of Rayleigh wave is greater when the half space is porous and elastic instead of dry sandy. GUI (graphical user interface) has been developed using MATLAB and a screenshot has been presented in the paper.
12
Content available On Rayleigh wave in generalized magneto-thermoelastic media with hydrostatic initial stress
Singh B., Kumari S., Singh J.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2012
|
Vol. 60, nr 2
349-352
EN
The governing equations of generalized magneto-thermoelasticity with hydrostatic initial stress are solved for surface wave solutions. The particular solutions in the half-space are applied to the boundary conditions at the free surface of the half-space to obtain the frequency equation of Rayleigh wave. The frequency equation is approximated for small thermal coupling and small reduced frequency. The velocity of propagation and amplitude-attenuation factor of Rayleigh wave are computed numerically for a particular material. Effects of magnetic field and hydrostatic initial stress on the velocity of the propagation and amplitude-attenuation factor are shown graphically.
13
Content available Application of Rayleigh wave to diagnostics of degradation of historic construction materials
Skłodowski M., Pinińska J., Łukaszewski P., Bobrowska A.
Diagnostyka
|
2011
|
nr 3(59)
19-24
EN
Paper presents results of degradation modelling of historical construction materials based on Rayleigh surface wave velocity (CR) measurement for two marbles widely used as the structural and decorative material in historical constructions. Environmental loading is modelled by freezing and thawing cycles performed in laboratory. Rayleigh wave measurement method does not need any coupling medium between the stone and ultrasonic probe and is 100% non-destructive. It is shown that exponential law can be used to model the proces of degradation of elastic properties of the tested materials.
PL
Praca przedstawia wyniki modelowania degradacji historycznych materiałów konstrukcyjnych na podstawie pomiarów prędkości fali Rayleigha dla dwóch marmurów szeroko stosowanych w zabytkowych budowlach jako materiał konstrukcyjny i dekoracyjny. Obciążenia środowiskowe modelowane są cyklami zamrażania i rozmrażania przeprowadzonymi w laboratorium. Metoda pomiaru fali Rayleigha nie wymaga żadnego ośrodka sprzęgającego pomiędzy materiałem a sondą ultradźwiękową i jest w 100% nieniszcząca. Wykazano, że proces degradacji właściwości sprężystych badanych materiałów dobrze modeluje prawo wykładnicze.
14
Content available remote Modelling of thermoelastic Lamb waves in a plate bordered with viscous fluid of varying temperature
Sharma J. N., Sharma R.
International Journal of Applied Mechanics and Engineering
|
2010
|
Vol. 15, no 1
217-236
EN
The propagation of thermoelastic waves in a homogeneous isotropic, thermally conducting plate bordered with layers (or half-spaces) of a viscous fluid on both sides is investigated. The problem has been modeled by employing non classical theory of thermoelasticity to carry the investigation. The secular equations for governing the symmetric and antisymmetric wave motion of the plate, in completely separate terms, are derived. The results in the context of classical conventional coupled and uncoupled theories of thermoelasticity in case of viscous and inviscid fluid loadings have been obtained as particular cases from the present analysis. The regions of the secular equation, waves of short wavelength and waves of long wavelength have also been discussed and deduced. Finally, in order to illustrate the analytical results, the numerical solution is carried out for an aluminum-epoxy composite material plate bordered with layers (or half-spaces) of light and heavy water. The results have been deduced and compared with the existing ones in relevant publications available in the literature at various stages of this work.
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