Frequency dependent directivity of guided waves excited by circular transducers in anisotropic composite plates

Глушков, Е. В.; Glushkova, Natalia; Eremin, Artem; Lammering, Rolf; Neumann, M. N.

doi:10.1121/1.4734392

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…As expected from the UEM imaging studies, the wave train emanating from the crystal/crystal interface propagates along a different direction and approximately follows the

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direction. This description is in reasonable agreement with previous studies of photoexcited acoustic phonons 48,49 . The second source may be relative differences in layer number (i.e., flake thickness) for each of the regions of interest.…”

Section: Resultssupporting

confidence: 89%

Defect-mediated phonon dynamics in TaS2 and WSe2

Cremons

Plemmons

Flannigan

2017

Structural Dynamics

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We report correlative crystallographic and morphological studies of defect-dependent phonon dynamics in single flakes of 1T-TaS2 and 2H-WSe2 using selected-area diffraction and bright-field imaging in an ultrafast electron microscope. In both materials, we observe in-plane speed-of-sound acoustic-phonon wave trains, the dynamics of which (i.e., emergence, propagation, and interference) are strongly dependent upon discrete interfacial features (e.g., vacuum/crystal and crystal/crystal interfaces). In TaS2, we observe cross-propagating in-plane acoustic-phonon wave trains of differing frequencies that undergo coherent interference approximately 200 ps after initial emergence from distinct interfacial regions. With ultrafast bright-field imaging, the properties of the interfering wave trains are observed to correspond to the beat frequency of the individual oscillations, while intensity oscillations of Bragg spots generated from selected areas within the region of interest match well with the real-space dynamics. In WSe2, distinct acoustic-phonon dynamics are observed emanating and propagating away from structurally dissimilar morphological discontinuities (vacuum/crystal interface and crystal terrace), and results of ultrafast selected-area diffraction reveal thickness-dependent phonon frequencies. The overall observed dynamics are well-described using finite element analysis and time-dependent linear-elastic continuum mechanics.

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“…As expected from the UEM imaging studies, the wave train emanating from the crystal/crystal interface propagates along a different direction and approximately follows the

210

Section: Resultssupporting

confidence: 89%

Defect-mediated phonon dynamics in TaS2 and WSe2

Cremons

Plemmons

Flannigan

2017

Structural Dynamics

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“…It is worth noting again that the wavenumbers of the latter are not f n but s nm of form (8). Let x ¼ WðkÞ ¼ Wðk; cÞ be one of the roots in the frequency domain.…”

Section: Comparison With Plane Wave Group Velocitymentioning

confidence: 99%

Group velocity of cylindrical guided waves in anisotropic laminate composites

Глушков

Glushkova

Eremin

et al. 2014

The Journal of the Acoustical Society of America

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An explicit expression for the group velocity of wave packets, propagating in a laminate anisotropic composite plate in prescribed directions, is proposed. It is based on the cylindrical guided wave asymptotics derived from the path integral representation for wave fields generated in the composites by given localized sources. The expression derived is theoretically confirmed by the comparison with a known representation for the group velocity vector of a plane guided wave. Then it is experimentally validated against laser vibrometer measurements of guided wave packets generated by a piezoelectric wafer active sensor in a composite plate.

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“…19 Modeling the frequency-dependent excitation of guided waves in generally anisotropic multilayered media is currently under investigation. 20,21 The response at the receiver can be expressed as…”

Section: Prediction Of Antisymmetric Wave Motion In a Plate With Lmentioning

confidence: 99%

Experimental analysis and prediction of antisymmetric wave motion in a tapered anisotropic waveguide

Moll

Wandowski

Malinowski

et al. 2015

The Journal of the Acoustical Society of America

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This paper presents experimental results for wave propagation in an anisotropic multilayered structure with linearly varying cross section. Knowing the dispersion and wave propagation properties in such a structure is of great importance for non-destructive material testing and structural health monitoring applications for accurate damage detection and localization. In the proposed study, the wavefield is generated by a circular piezoelectric wafer active sensor and measured by a scanning laser-Doppler-vibrometer. The measurements are compared with a theoretical group delay estimation and a signal prediction for the antisymmetric wave motion along the non-uniform propagation path. The required dispersion curves are derived from the well-known global matrix method for segments of constant thickness. A multidimensional frequency-wavenumber analysis of linescan data and the full wavefield provides further insight of the adiabatic wave motion because the wavenumber changes along the tapered geometry of the waveguide. In addition, it is demonstrated that a terahertz time-domain system can be used in glass-fiber reinforced plastic structures as a tool to estimate the thickness profile of thin structures by means of time-of-flight measurements. This information is particularly important for guided wave-based diagnostics of structures with unknown thickness.

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Frequency dependent directivity of guided waves excited by circular transducers in anisotropic composite plates

Cited by 8 publications

References 12 publications

Defect-mediated phonon dynamics in TaS2 and WSe2

Defect-mediated phonon dynamics in TaS2 and WSe2

Group velocity of cylindrical guided waves in anisotropic laminate composites

Experimental analysis and prediction of antisymmetric wave motion in a tapered anisotropic waveguide

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