Academic literature on the topic 'Elastic wave conversion'
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Journal articles on the topic "Elastic wave conversion"
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Paul, Anne, and Michel Campillo. "Diffraction and conversion of elastic waves at a corrugated interface." GEOPHYSICS 53, no. 11 (November 1988): 1415–24. http://dx.doi.org/10.1190/1.1442421.
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Numerical modeling is used to investigate the effect of small‐scale irregularities of a reflecting boundary on elastic wave reflections. The scattered wave field is computed by using a discretized form of boundary integral equations and a plane‐wave decomposition of seismic wave fields. For various values of incidence angle of the P wave, we compute the distribution of diffracted energy for both P waves and S waves as a function of reflection angle. We show that corrugations with mean wavelength of the order of, or smaller than, the seismic wavelength have little effect on the reflected P wave. However, the pattern of P‐to‐S conversion is very different from that with a plane boundary. Scattered S waves appear at postcritical angles for any angle of incidence of the P wave. The amplitude of these nongeometrical shear waves decreases rapidly with decreasing amplitude of the corrugations, or when the mean wavelength of the corrugations becomes larger than the dominant seismic wavelength. The local geometry of the irregularities has a negligible effect on the scattered S waves. By analogy with perturbation theory, we propose interpreting the postcritically scattered S waves as the contribution to the shear wave field of converted inhomogeneous P waves diffracted along the boundary.
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Xu, Shibo, and Alexey Stovas. "Estimation of the conversion point position in elastic orthorhombic media." GEOPHYSICS 84, no. 1 (January 1, 2019): C15—C25. http://dx.doi.org/10.1190/geo2018-0375.1.
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Determination of the conversion point position is very important to carry out seismic processing in the common conversion point gather of converted wave data. The anisotropic effect is very obvious for a converted wave when estimating the physical and processing parameters from real data. To estimate the conversion point in an elastic orthorhombic (ORT) medium, we have defined an explicit rational form approximation for the radial coordinate of the conversion point for converted [Formula: see text], [Formula: see text], and [Formula: see text] waves. To obtain the approximation coefficients, the Taylor series approximation in the corresponding vertical slowness for three pure wave modes is applied. The coefficients in our proposed approximation are computed within two vertical symmetry planes. The difference between the acquisition azimuth and the azimuth of the conversion point position is analyzed for different combinations of the wave modes. The accuracy of the conversion point position estimation for three ORT models is illustrated in the numerical examples. One can see from the results that for converted [Formula: see text] and [Formula: see text] waves, our approximation is very accurate in estimating the conversion point position regardless of the tested ORT model. For a converted [Formula: see text] wave, due to the existence of cusps, triplications, and shear singularities, the error in conversion point estimation is relatively larger compared with PS-waves in the vicinity of the singularity point.
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Belyayev, Yu N., E. I. Yashin, and O. Y. Yashina. "Conversion of Elastic Wave Polarization in Calcium Molybdate Layer." Solid State Phenomena 284 (October 2018): 95–100. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.95.
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Scattering of elastic waves in calcium molybdate films is considered. The transformation of elastic waves as a result of six-beam diffraction in an anisotropic layer is analyzed. This analysis is based on the transfer matrix method. The distribution of incident wave energy between six scattered waves is characterized by conversion coefficients. The method for conversion coefficients calculations is presented. It does not require solving algebraic problem on eigenvalues for waves in an anisotropic layer. Features of dependencies of conversion coefficients of CaMoO4 layers on angles of incidence, frequency and the thickness of the layer are demonstrated.
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Zeng, Yuehua. "Theory of scattered P- and S-wave energy in a random isotropic scattering medium." Bulletin of the Seismological Society of America 83, no. 4 (August 1, 1993): 1264–76. http://dx.doi.org/10.1785/bssa0830041264.
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Abstract A new theory is presented to study the scattered elastic wave energy propagation in a random isotropic scattering medium. It is based on a scattered elastic wave energy equation that extends the work of Zeng et al. (1991) on multiple scattering by considering S to P and P to S wave scattering conversions. We obtain a complete solution of the scattered elastic wave energy equation by solving the equation in the frequency/wave-number domain. Using a discrete wave-number sum technique combined with a modified repeated averaging and the FFT method, we compute numerically the complete solution. By considering that the scattering conversion from P- to S-wave energy is about (α/β)4 times greater than that from S to P waves (Aki, 1992), we found that the P-wave scattering field was converted quickly to the S-wave scattering field, leading to the conclusion that coda waves generated from both P- and S-wave sources are actually dominated by scattered S waves. We also compared our result with that obtained under the acoustic wave assumption. The acoustic wave assumption for seismic coda works quite well for the scattered S-wave field but fails for the scattered P-wave field. Our scattered elastic wave energy equation provides a theoretical foundation for studying the scattered wave field generated by a P-wave source such as an explosion. The scattered elastic wave energy equation can be easily generalized to an inhomogeneous random scattering medium by considering variable scattering and absorption coefficients and elastic wave velocities in the earth.
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De Ponti, Jacopo Maria, Luca Iorio, and Raffaele Ardito. "Graded elastic meta-waveguides for rainbow reflection, trapping and mode conversion." EPJ Applied Metamaterials 9 (2022): 6. http://dx.doi.org/10.1051/epjam/2022004.
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Precise control of elastic waves is a challenge for many applications in the field of mechanical vibrations, ultrasonic inspection, and energy harvesting. Graded arrays of resonators on elastic substrates recently revealed superior performances for broadband wave trapping and mode conversion. In this study we present elastic waveguides able to govern waves at different scales exploiting rainbow reflection, trapping and mode conversion. We investigate whether these mechanisms, and the associated control, can be used for energy harvesting or signal conversion devices.
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Lee, Jin Kyung, Sang Ll Lee, Joon Hyun Lee, and Young Chul Park. "Propagation Characteristic of Elastic Wave in Pipe." Key Engineering Materials 345-346 (August 2007): 1323–26. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.1323.
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In this study, elastic waves of ultrasonic and acoustic emission were used to evaluate the propagation characteristic of the wave in pipe, and study on mode conversion of the elastic wave due to the cracks in the pipe was also performed. An acoustic emission (AE) sensor was used to receive the propagated ultrasonic wave. AE technique has a merit that it can identify the received ultrasonic wave by the analysis of the AE parameters such as count, energy, frequency, duration time and amplitude. For transmitting and receiving of the wave, a wedge for universal angle was manufactured. The optimum angles for transmitting of ultrasonic wave and signal receiving at the attached AE sensor on the pipe were determined. Theoretical dispersion curve was compared with the results of the time-frequency analysis based on the wavelet transformation. The received modes showed a good agreement with theoretical one. The used ultrasonic sensor was 1MHz, and AE sensor was broadband (100kHz – 1200kHz). The artificial cracks were induced in the pipe to measure the propagation characteristics of the elastic wave for the cracks. AE parameters for the received signals were also varied with the crack types in the pipe. AE parameters of amplitude and duration time were more effective factors than the analysis of mode conversion for evaluation of the cracks in the pipe.
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Li, Ke, Shuangxi Jing, Jiangong Yu, and Bo Zhang. "Complex Rayleigh Waves in Nonhomogeneous Magneto-Electro-Elastic Half-Spaces." Materials 14, no. 4 (February 21, 2021): 1011. http://dx.doi.org/10.3390/ma14041011.
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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.
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Parker, Samuel D., Michael R. Haberman, and Daniel R. Roettgen. "Time-varying elastic wave mode conversion in vibrating elastic beams with subwavelength nonlinearity." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A294. http://dx.doi.org/10.1121/10.0016326.
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Introduction of time-varying properties in a background medium can enable unconventional wave behavior. Furthermore, it is well-known that subjecting nonlinear materials to time-varying stress can be used for material characterization [Appl. Phys. Lett. 94, 011905 (2009)]. We propose a technique called Dynamic Asymmetric Transmission Measurement (DATM) that combines structural dynamic (SD) and ultrasonic (US) testing modalities in an elastic waveguide to detect and characterize changes in the global stress state of a structure that result in local time-varying stress conditions due to local nonlinearity. Asymmetric geometric features in beams and plates, paired with time-varying stress conditions, result in asymmetric mode conversion of guided US waves that depend on large-scale structural dynamics. The DATM technique is explored through finite element modeling, semi-analytical methods, and experiments and discussed in a structural health monitoring context. We also discuss the use of dynamic structures with engineered defects to introduce time-varying stress conditions for the purpose of manipulating elastic waves. [Sandia National Laboratories is a multimission laboratory managed and operated by the National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.]
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Belyayev, Yuriy N. "Calculation of the Six-Beam Diffraction in Layered Media Using Polynomials of Principal Minors." Journal of Theoretical and Computational Acoustics 26, no. 02 (June 2018): 1850017. http://dx.doi.org/10.1142/s2591728518500172.
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The scattering of plane elastic waves by an anisotropic layered medium in the case of the six-beam diffraction is considered. The matrix method for solving wave equations is developed. The conversion coefficients [Formula: see text] for the three types of incident waves (horizontally polarized shear wave, vertically polarized shear wave and longitudinal wave) are defined. Representations of coefficients [Formula: see text] through elements of transfer matrix are found. The method for coefficients [Formula: see text] calculations is presented. It does not require the solving of algebraic problem on eigenvalues for waves in an anisotropic layer. Some features of the functional dependencies of [Formula: see text] on the angles of incidence, wave frequency and layer thickness are demonstrated on several examples of the crystals in a three-layer model. It is shown that the conversions SH wave into SV waves and SV wave into SH waves are equivalent.
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Wandowski, Tomasz, Pawel Malinowski, and Wieslaw Ostachowicz. "Analysis of S0/A0 elastic wave mode conversion phenomenon in glass fibre reinforced polymers." MATEC Web of Conferences 188 (2018): 01009. http://dx.doi.org/10.1051/matecconf/201818801009.
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In this paper results of experimental analysis of elastic guided wave mode conversion phenomenon in glass fibre reinforced polymers GFRP are presented. Results of research presented in this paper are strictly focused on S0/A0' mode conversion caused by discontinuities in the form of circular teflon insert simulating damage and impact damage. Experimental research is based on non-contact elastic wave sensing with utilisation of scanning laser Doppler vibrometer SLDV and full wave-field measurements. In presented research influence of location of circular teflon insert on S0/A0' mode conversion is investigated. Teflon inserts were located between layers of composite material at different depth. Moreover influence of impact damage with different energy on S0/A0' mode conversion is investigated. Analysis of influence of investigated discontinuities on S0/A0' mode conversion are based on the elastic wave mode filtration in frequency-wavenumber domain. Mode filtration process allows to remove effects of unwanted type of mode propagation in forward or backward direction. Effects of S0/A0' mode conversion are characterise by mode conversion indicator based on amplitude of new mode A0'.
Dissertations / Theses on the topic "Elastic wave conversion"
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Yi, Kaijun. "Controlling guided elastic waves using adaptive gradient-index structures." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC044/document.
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Les matériaux à gradient d'indice de réfraction (GRIN) présentent des propriétés mécaniques variant en temps ou/et en espace. Ils ont été testés pour des applications prometteuses dans de nombreuses applications d'ingénierie, comme pour le contrôle santé structurale ou la surveillance de structure (SHM), le contrôle des vibrations et bruit, la récupération d'énergie, etc. D'un autre côté, les matériaux piézoélectriques offrent la possibilité de réaliser des cellules composites dont les propriétés mécaniques peuvent être contrôlées en ligne. Motivé par ces deux approches, cette thèse étudie la mise en œuvre de structures GRIN adaptatifs pour le contrôle des ondes élastiques. Deux types de structures GRIN adaptatifs sont étudiés dans ce travail. Le premier exemple concerne la mise en œuvre d'une lentille piézoélectrique dans une plaque. Il est composé de patchs piézoélectriques shuntés, collés périodiquement en surface du guide d'ondes. Les circuits de shunt utilisés permettent d'émuler une capacité négative (NC). En accordant les valeurs de NC on peut ajuster l'indices de réfraction du milieu à l'intérieur de la lentille piézoélectrique et pour satisfaire une fonction sécante hyperbolique. Les résultats numériques montrent que les lentilles piézoélectriques peuvent alors focaliser les ondes de flexion de la plaque sur les points focaux. La lentille piézoélectrique est efficace dans une grande bande de fréquences et efficace dans une grande plage de fonctionnement. Ainsi elle peut focaliser des ondes sur différent points par simple ajustement des valeurs de NC réalisés par le circuit. Cette focalisation adaptative la rend très intéressante pour de nombreuses applications comme la récupération d'énergie ou le SHM. La mise en œuvre de ces techniques pour la récupération d'énergie est discutée dans cette thèse. Le second exemple concerne l'étude d'une structure dont les propriétés mécaniques sont contrôlées en temps et en espace. En particulier, une modulation périodique permet de créer une onde artificielle se propageant dans la structure. L'interaction avec des ondes mécaniques entraîne une rupture de réciprocité visible dans un diagramme de bande non symétrique. De nombreux phénomènes inhabituels sont observés dans ce type de structures variables : fractionnement des fréquences, conversion d'ondes et transmission unidirectionnelles. Deux types de conversion fréquentielle sont démontrés et expliqués. Le premier est induit par la transmission d'énergie entre les différents modes Bloch et le second type est dû à la diffusion de Bragg dans les structures modulées. La transmission unidirectionnelle des ondes pourrait être exploitée pour réaliser des diodes dans des systèmes infinis ou semi-infinis. Cependant, la transmission unidirectionnelle n'existe pas dans les systèmes finis en raison des phénomènes de conversion de fréquenceGRadient INdex (GRIN) media are those whose properties smoothly vary in space or/and time. They have shown promising effects in many engineering applications, such as Structural Health Monitoring (SHM), vibration and noise control, energy harvesting, etc. On the other hand, piezoelectric materials provide the possibility to build unit cells, whose mechanical properties can be controlled on-line. Motivated by these two facts, adaptive GRIN structures, which can be realized using shunted piezoelectric materials, are explored in this dissertation to control guided elastic waves. Two types of adaptive GRIN structures are studied in this work. The first type is a piezo-lens. It is composed of shunted piezoelectric patches bonded on the surfaces of plates. To control the mechanical properties of the piezoelectric composite, the piezoelectric patches are shunted with Negative Capacitance (NC). By tuning the shunting NC values, refractive indexes inside the piezo-lens are designed to satisfy a hyperbolic secant function in space. Numerical results show that the piezo-lens can focus waves by smoothly bending them toward the designated focal point. The piezo-lens is effective in a large frequency band and is efficient in many different working conditions. Also the same piezo-lens can focus waves at different locations by tuning the shunting NC values. The focusing effect and tunable feature of piezo-lens make it useful in many applications like energy harvesting and SHM. The former application is fully discussed in this thesis. The focusing effect at the focal point results in a known point with high energy density, therefore harvesting at the focal point can yield more energy. Besides, the tunable ability makes the harvesting system adaptive to environment changes. The second type is the time-space modulated structure. Its properties are modulated periodically both in time and space. Particularly, the modulation works like a traveling wave in the structure. Due to the time-varying feature, time-space modulated structures break the reciprocity theorem, i.e., the wave propagation in them is nonreciprocal. Many unusual phenomena are observed during the interaction between waves and time-space modulated structures: frequency splitting, frequency conversion and one-way wave transmission. Two types of frequency conversion are demonstrated and explained. The first type is caused by energy transmission between different orders Bloch modes. The second type is due to the Bragg scattering effect inside the modulated structures. The one-way wave transmission could be exploited to realize one-way energy insulation in equivalent infinite or semi-inffnite systems. However, the one-way energy insulation fails in finite systems due to the frequency conversion phenomenon
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Ahmed, Mustofa N. "A Study of Guided Ultrasonic Wave Propagation Characteristics in Thin Aluminum Plate for Damage Detection." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1387732124.
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Gendron, Benjamin. "Modélisation et optimisation d’un système de récupération de l’énergie des vagues électro-actif déformable." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0024.
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Les convertisseurs d'énergie des vagues ont beaucoup évolué depuis les premiers prototypes dans les années 1970. D'abord rigides et composés de sections articulées, de nouveaux systèmes houlomoteurs sont maintenant entièrement flexibles comme le S3 développé par l'entreprise SBM Offshore. Ce système est composé d'un tube élastique fermé et rempli d'eau dont les déformations radiales sont directement converties en électricité grâce à l'utilisation de bagues en polymère électro-actif. L'objectif de cette thèse est de développer un modèle numérique qui soit capable de prédire le comportement du système houlomoteur déformable dans tout type d'environnement marin. À partir d'expériences sur modèles réduits, il a été possible d'analyser le comportement de la structure et de construire un modèle numérique qui prenne en compte les différents phénomènes physiques agissant sur le convertisseur. Le modèle est développé à partir d'une décomposition modale des déformations du tube. Le comportement non-linéaire du matériau est pris en compte grâce à la théorie hyperélastique et l'interaction houle-structure est réalisée à l'aide de la méthode d'éléments de frontières linéaires. Deux versions ont été développées, une fonctionnant dans le domaine fréquentiel linéaire et une autre dans le domaine temporel afin de prendre en compte les effets non-linéaires. Au final, les simulations fournies par le modèle développé sont comparées aux mesures réalisées en bassin afin de valider les résultatsWave energy converters have greatly improved since the first generation in the 1970s. At first rigid with articulated sections, new wave energy converters are now entirely flexible like the S3 developped by the company SBM Offshore. The device is made of a water filled elastic tube closed at both ends and the radial deformations are directly converted into electricity by the use of electro-active polymere rings. The objective of this thesis is to develop a numerical model that can predict the behaviour of this flexible wave energy converter in any kind of environment. After performing scaled model tests, it has been possible to analyse the behaviour of the device and build a numerical model that takes into account the different physical effects acting on the wave energy converter. The numerical model is based on a modal decomposition of the tube deformations. The wall non-linear effects are taken into account with the use of the hyper-elastic theory and the wave-structure interaction is made possible with the linear boundary element method. Two different versions have been developped. One based on the linear frequency domain and the other working in the time domain in order to take into account the non-linear effects. Finally, The simulations are compared with the measures from the basin tests to validate the results
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Parpiiev, Tymur. "Ultrafast magneto-acoustics in magnetostrictive materials." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1044/document.
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Avec l’avènement du laser femtoseconde il est devenu possible de mesurer comment la démagnétisation femtoseconde peut permettre de sonder l’interaction d’échange dans les métaux ferromagnétiques. La démagnétisation induite par laser d’un matériau avec un fort couplage magnéto-élastique amène à la relaxation des contraintes mécaniques, générant ainsi des ondes acoustiques longitudinales (L) et transversales (T). Dans ce travail de thèse, la génération d’impulsions acoustiques picosecondes T par le mécanisme de démagnétostriction dans des matériaux fortement magnétostrictifs est traitée analytiquement et montrée expérimentalement dans le cas d’un alliage de Terfenol. En premier lieu, nous avons développé un modèle phénoménologique de magnétostriction directe dans un film monocristallin de Terfenol. Les expériences pompe-sonde linéaire MOKE résolues en temps montrent que la relaxation transitoire des contraintes magnéto-élastiques du film amène à l’excitation d’ondes GHz acoustiques L at T. Ces résultats sont la première observation expérimentale de l’excitation d’ondes acoustiques transversales picoseconde par mécanisme de démagnétostriction induit par laser. En second lieu, nous avons analysé le processus d’interaction d’ondes acoustiques L avec l’aimantation d’un film mince de Terfenol. L’onde acoustique picoseconde produit un changement de magnétisation du film et induit la conversion de modes acoustiques. C’est une autre voie de génération d’ondes acoustiques T que nous avons mis en évidence. La gamme de fréquence des impulsions générées est liée à l’échelle de temps de démagnétisation, qui corresponds à quelques centaines de GHz - 1 THzWith the advent of femtosecond lasers it became possible to measure how femtosecond optical demagnetization can probe the exchange interaction in ferromagnetic metals. Laser-induced demagnetization of materials with strong magneto-elastic coupling should lead to the release of its build-in strains, thus to the generation of both longitudinal (L) and shear (S) acoustic waves. In this thesis, generation of shear picosecond acoustic pulses in strongly magnetostrictive materials such as Terfenol is processed analytically and shown experimentally. In case of Terfenol with strong magneto-crystalline anisotropy, laser induced demagnetostriction is responsible for S excitation. First, the phenomenological model of direct magnetostriction in a Terfenol monocrystalline film is developed. The shear strain generation efficiency strongly depends on the orientation of the film magnetization. Time-resolved linear MOKE pump-probe experiments show that transient laser-induced release of the magnetoelastic strains lead to the excitation of GHz L and S acoustic waves. These results are the first experimental observation of picosecond shear acoustic wave excitation by laser-induced demagnetostriction mechanism. Second, the interaction of an optically generated L acoustic pulse with the magnetization of a Terfenol thin film is reported. Arrival of the picosecond strain wave alters a change of its magnetization and leads to acoustic mode conversion, which is another pathway of shear acoustic wave generation. The frequency bandwidth of the generated acoustic pulses matches the demagnetization timescale and lies in the range of several hundreds of GHz, close to 1 THz
Book chapters on the topic "Elastic wave conversion"
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Chimenti, Dale, Stanislav Rokhlin, and Peter Nagy. "Reflection and Refraction of Waves at a Planar Composite Interface." In Physical Ultrasonics of Composites. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195079609.003.0008.
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Nondestructive ultrasonic testing of composite materials is affected by several special features of wave propagation that arise from the strong anisotropy and inhomogeneity of these materials. The resulting complexity requires re-examination of old testing methodologies and development of new ones. One of the most fundamental phenomena in ultrasonic nondestructive evaluation is the reflection–refraction of ultrasonic waves at a plane interface. Even the simplest test procedure requires understanding of mode conversion and knowledge of elastic wave reflection and transmission coefficients and refraction angles. Reflection–refraction phenomena, while straightforward and well documented for isotropic materials, are much more complicated for anisotropic materials. When analyzing the oblique incidence inspection method for composite materials, one first has to address the problem of wave propagation through the interface between the coupling medium and the composite material. For example, there is an inherent fluid/composite interface in the immersion technique and a perspex/composite interface in the contact method. In the latter case, assuming that a thin fluid layer is applied to facilitate coupling through the interface, slip rather than welded boundary conditions prevail. Another example of great practical importance is the case of multidirectional fiber plies in a composite laminate, when the reflection and transmission of ultrasonic waves from one ply to another with a different orientation must be considered. Before discussing the general problem of wave refraction in anisotropic composite materials, let us review the simple isotropic case. Consider a plane interface between two isotropic elastic media in “welded” (perfectly bonded) contact, implying continuity of tractions and displacements across the interface, although the boundary conditions are not important at this point. Figure 4.1 shows a schematic diagram of a plane wave with wavenumber ki incident on the interface at angle θi. The parallel lines with spacing equal to the incident wavelength λi correspond to equal-phase planes orthogonal to the incident plane. By definition, the wavenumber ki = 2π/λi is the magnitude of the wave vector ki. The incident wave is converted at the interface into reflected and transmitted waves. The refraction angle of the transmitted wave is θr and its wavenumber is kr.
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"Reflection, Transmission, and Mode Conversion of Elastic Plane Waves at Planar Boundaries between Homogeneous Nondissipative Materials." In Ultrasonic Nondestructive Testing of Materials, 309–94. CRC Press, 2012. http://dx.doi.org/10.1201/b11724-12.
Full textConference papers on the topic "Elastic wave conversion"
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Rhee, Huinam. "A New Analysis of Elastic Wave Resonance Scattering From an Elastic Cylinder." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0526.
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Abstract The problem of elastic wave resonance scattering from elastic targets is discussed in this paper. A new resonance formalism to extract the elastic resonance information of the target from scattered elastic waves is introduced. The new resonance formalism is an extension of the works developed for acoustic wave scattering problems by the author. The classical resonance scattering theory (RST), which is usually being used for this type of problem, computes reasonable magnitude information of the resonances in each partial wave, but the phase behaves in somewhat irregular way, therefore, is not clearly explainable. The new method has been developed to obtain physically meaningful magnitude and phase of the resonances. As an example problem, elastic wave scattering from an infinitely-long elastic cylinder was analyzed by the proposed new method and compared with the previous studies by RST. In case of no mode conversion, both methods generate identical magnitude. However, the new method computes exact π radian phase shifts through resonances and anti-resonances while RST produces physically unexplainable phases. In case of mode conversion, even magnitudes are slightly different. The phase shifts through resonances and antiresonances obtained by the new method are not exactly π radians due to energy leak by mode conversion. But. the phases by the new method still show more reasonable and intuitive behavior than those by RST.
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Shoro, Takuya, Hiroki Kishikawa, and Nobuo Goto. "Optical OAM Mode Conversion by Higher Order Elastic Vortex Wave." In 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC). IEEE, 2019. http://dx.doi.org/10.23919/ps.2019.8817832.
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Langenberg, K. J., and A. Zimmer. "Utilization of elastic wave mode conversion in electromagnetic diffraction tomographic imaging schemes." In 2009 International Conference on Electromagnetics in Advanced Applications (ICEAA). IEEE, 2009. http://dx.doi.org/10.1109/iceaa.2009.5297629.
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Georgiou, Ioannis T. "On the Physics of Conversion of Longitudinal Elastic Waves Into Extended Vibrations in a Suspended Aluminum Rod." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65726.
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This work concerns a two stage decomposition analysis of a dynamics phenomenon due to reflection of longitudinal pulse elastic waves in long elastic rods. Elastic pulse waves are induced by impacting a miniature modal hammer at one of its free ends whereas its dynamics is recorded by a high performance piezoelectric sensor at the other end. An underlining characteristic time scale leads to a natural decomposition of experimental time series of wave acceleration into a sequence of time frames. The signals are viewed as a sequence of time frames and thus are analyzed globally and locally by further decomposing them into their intrinsic Proper Orthogonal Decomposition Modes (POD) or Principal Component Analysis (PCA) modes. It is found that experimental signals of acceleration during propagation of elastic pulse waves are governed by a small number of POD modes; one of the modes is dominant. It is conjectured that these intrinsic modes of the time frame-arranged signals represent physical modes of pulse wave propagation. The introduced method of the two-stage decomposition analysis is potentially useful for data-driven analysis in wave propagation-based damage detection.
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Zhang, Minghui, Hui Sun, Tielin Sun, Wenjian Chen, and Tianhang Zhang. "Research on mode conversion of lamb wave at dip end face of elastic plate." In 2016 IEEE/OES China Ocean Acoustics (COA). IEEE, 2016. http://dx.doi.org/10.1109/coa.2016.7535722.
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Shoro, Takuya, Hiroki Kishikawa, and Nobuo Goto. "Analysis of Optical OAM Mode Conversion Using Elastic Vortex Wave in Graded Index Optical Fiber." In Photonic Networks and Devices. Washington, D.C.: OSA, 2018. http://dx.doi.org/10.1364/networks.2018.new1f.1.
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Zhou, B., Y. Wang, S. Greemhalgh, and X. Liu. "Frequency-Domain Wavefield Differences and Conversion Between 2.5D and 2D Seismic Wave Modelling in Elastic Anisotropic Media." In 81st EAGE Conference and Exhibition 2019. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201901537.
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Wu, Ji, Cetin Cetinkaya, and Chen Li. "An Efficiency Study of Laser-Induced Thermoelastic Wave Generation in Layers." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1646.
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Abstract The elastic wave generation and the efficiency of the thermal-to-mechanical energy conversion process of elastic wave generation by laser excitation are studied. A previously developed transfer matrix formulation [3, 4] is reviewed and the transient response in a silicon layer is computed by employing FFT. The transient thermal and mechanical response of a layer are considered, and the transient temperature, stress, acceleration and mechanical power are obtained under micro-second level excitation. The generation efficiency for the elastic wave components, which are utilized to evaluate the state of layered structures, is examined for a silicon layer. The results presented are useful in determining instrument specification, such as laser power, receiver dynamic range, and test set-up design.
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Alam, Mohammad-Reza. "A Flexible Seafloor Carpet for High-Performance Wave Energy Extraction." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-84034.
Full textAbstract:
Similar to the mechanism by which a visco-elastic mud damps the energy of overpassing surface waves, if the near-shore seafloor is carpeted by an elastic thin material attached to generators (i.e. dampers) a high fraction of surface wave energy can be absorbed. Here we present analytical modeling of the flexible carpet wave energy converter and show that a high efficiency is achievable. Expressions for optimal damping and stiffness coefficients are derived and different modes of oscillations are discussed. The presented wave energy conversion scheme is completely under the water surface hence imposes minimal danger to boats and the sea life (i.e. no mammal entanglement). The carpet is survivable against high momentum of storm surges and in fact can perform well under very energetic (e.g. stormy) sea conditions, when most existing wave energy devices are needed to shelter themselves by going into an idle mode. I am honored to be a colleague of Prof. Ronald Yeung at the University of California, Berkeley. He is a world renowned scientist of ship hydrodynamics with several valuable and key contributions to the field. This manuscript on a new ocean wave energy extraction scheme is due to Ron’s recent interest in the field of ocean renewable energy. I am looking forward to years of working closely with him. Thank you Ron.
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Yi, Kaijun, Manuel Collet, and Sami Karkar. "Unusual Dynamic Behaviors Induced by Time-Space Modulated Structures." In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3777.
Full textAbstract:
Time-space modulated structures (or dynamic structures) possess properties modulated both in time and space. They have been extensively studied in diverse areas. This presented work theoretically studies the unusual wave propagation phenomena induced by elastic waves incident on time-space modulated beams. The scattering matrix is developed to predict the characteristics of the reflected and transmitted waves. It is shown that the scattering matrix directly indicates the non-reciprocal wave transmission and frequency splitting phenomena caused by the dynamic beam, it also reveals a frequency conversion phenomenon, which is rarely noticed by researchers but has very significant influence on the application of dynamic structures.