Acoustic flux imaging in anisotropic media

Weaver, Richard L.; Hauser, Matt R.; Wolfe, J. P.

doi:10.1007/bf01321030

Cited by 55 publications

(18 citation statements)

References 23 publications

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“…This behaviour in the geometric shadow has been predicted by Maris in 1983 [1], by applying to phonons analysis the pioneerly work performed by Pearcey in electromagnetism [2]. It has been experimentally observed at ultrasonic frequencies by making use of quasi-monochromatic sources [3][4][5]. This phenomenom of diffraction at an edge, which is observed although no actual screen spatially limits the radiation, is called internal diffraction or diffraction at the cusp edge.…”

Section: Introductionmentioning

confidence: 78%

Complex surface rays associated with inhomogeneous skimming and Rayleigh waves

Deschamps¹,

Huet²

2009

International Journal of Non-Linear Mechanics

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The Rayleigh wave, that propagates at the free surface of semi-infinite anisotropic medium, is composed of three inhomogeneous partial waves, each propagating along the surface with a different attenuation along the depth. Since this wave does not exhibit an attenuation on the surface, let us call it the homogeneous Rayleigh wave. The associated slowness corresponds to the real solution of the Rayleigh dispersion equation. Besides this classical solution, an infinite number of complex solutions of the Rayleigh dispersion equation exits. For such particular Rayleigh waves, the slowness vector, i.e. the identical component on the surface of the slowness of each partial waves, is taken to be complex. Thus, these Rayleigh waves are attenuated on the surface and as shown here, their attenuation is normal to the ray direction (or the energy velocity direction). Similarly to the infinite inhomogeneous plane waves which can be associated with complex rays, we call these waves, inhomogeneous Rayleigh waves. We use the inhomogeneous skimming waves, which are inhomogeneous plane waves, and the inhomogeneous Rayleigh waves to explain differently the usual diffraction phenomena on the free surface which cannot be explained by the real ray theory. For example, the arrival time of the wave packet observed beyond the cusp is in perfect accordance with the arrival time of some specific inhomogeneous Rayleigh waves. We show that these results are in agreement with the computation of the Green function. They apply to the theory of surface waves in linear elastodynamics with intrinsic anisotropy as well as to the theory of surface waves in linearized (incremental) elastodynamics with strain- A c c e p t e d m a n u s c r i p tPage 2 induced anisotropy (also known as small-amplitude waves superimposed on the large static homogeneous deformation of a nonlinear solid).

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Section: Introductionmentioning

confidence: 78%

Complex surface rays associated with inhomogeneous skimming and Rayleigh waves

Deschamps¹,

Huet²

2009

International Journal of Non-Linear Mechanics

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“…It allows one to avoid the problem of acoustical mismatch, typical for the coherent wave transducers, and to make the correct comparison of the angular dependencies of lattice excitations fluxes of both types. Such comparison is actual because focusing is observed not only for nonequilibrium phonons but also for coherent waves [3,4]. …”

Section: Introductionmentioning

confidence: 96%

Time resolved response of 2DEG to the coherent component accompanying heat pulses in GaAs

Danilchenko¹,

Slutskii

Paszkiewicz

2004

phys. stat. sol. (c)

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The two components, coherent and non-coherent, of acoustical excitations accompanying heat pulse generation have been investigated in GaAs. It was shown that delta-doped layers imbedded into the GaAs crystal exhibit the peculiar property to be sensitive to a high frequency phonon flux and to concomitant coherent acoustic waves simultaneously. The time resolved measurements allow separating longitudinal LA and transverse TA acoustic excitations and investigating the intensity behavior as a dependence on the crystallographic direction of the propagation. The semi quantitative analysis of the layers response to coherent waves of different polarizations has been proposed.

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“…The phonon focusing patterns have been well documented in the experimental and theoretical studies. [6][7][8][9][10][11] Theoretically, a set of critical conditions for the presence of various types of caustics in cubic crystals was elegantly formulated by calculating group velocities in the vicinity of symmetry directions. 6,7 The Gaussian curvature in the vicinity of symmetry axes in the crystals of various symmetries was also studied in order to formulate critical conditions for some caustics.…”

Section: Introductionmentioning

confidence: 99%

Caustic and anticaustic points in the phonon focusing patterns of cubic crystals

Wang

2008

The Journal of the Acoustical Society of America

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Phonon focusing patterns are dependent on the existence of concave/saddle regions and acoustic axes in the slowness surface. The main feature of the focusing patterns in cubic crystals can be characterized by the caustic and anticaustic points in the symmetry planes. By applying the Stroh formalism, the caustic and anticaustic points in the symmetry planes are investigated in relation to degeneracies in the Stroh eigenvalue equation. A set of analytical expressions for the locations of the caustic and anticaustic points is derived for cubic crystals.

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Acoustic flux imaging in anisotropic media

Cited by 55 publications

References 23 publications

Complex surface rays associated with inhomogeneous skimming and Rayleigh waves

Complex surface rays associated with inhomogeneous skimming and Rayleigh waves

Time resolved response of 2DEG to the coherent component accompanying heat pulses in GaAs

Caustic and anticaustic points in the phonon focusing patterns of cubic crystals

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