Numerical and analytical calculation of modal excitability for elastic wave generation in lossy waveguides

Treyssède, Fabien; Laguerre, Laurent

doi:10.1121/1.4802651

Cited by 30 publications

(39 citation statements)

References 42 publications

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“…8 The theory and simulation of laser generated waves propagating in plates has been the object of several studies. 9,10 In a recent paper, Laguerre and Tresseyde 11 proposed a method to calculate the excitability of both propagating and non propagating modes. In practice, the energy deposited on the plate by the source of finite dimensions rapidly flows out of the source area except for non propagative modes.…”

Section: Introductionmentioning

confidence: 99%

Temporal behavior of laser induced elastic plate resonances

2014

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This paper investigates the dependence on Poisson's ratio of local plate resonances in low attenuating materials. In our experiments, these resonances are generated by a pulse laser source and detected with a heterodyne interferometer measuring surface displacement normal to the plate. The laser impact induces a set of resonances that are dominated by Zero Group Velocity (ZGV) Lamb modes. For some Poisson's ratio, thickness-shear resonances are also detected. These experiments confirm that the temporal decay of ZGV modes follows a $t^{-0.5}$ law and show that the temporal decay of the thickness resonances is much faster. Similar decays are obtained by numerical simulations achieved with a finite difference code. A simple model is proposed to describe the thickness resonances. It predicts that a thickness mode decays as $t^{-1.5}$ for large times and that the resonance amplitude is proportional to $D^{-1.5}$ where $D$ is the curvature of the dispersion curve $\omega(k)$ at $k=0$. This curvature depends on the order of the mode and on the Poisson's ratio, and it explains why some thickness resonances are well detected while others are not.Comment: 8 pages, 7 figures. Wave Motion 201

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Section: Introductionmentioning

confidence: 99%

Temporal behavior of laser induced elastic plate resonances

2014

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“…[23][24][25][26], and so this is only briefly reported here. The displacements 1 ′ in region Ω 1 of the pipe (regions Ω 1 and Ω 3 are assumed to be identical) are expanded over the pipe eigenmodes to give…”

Section: Eigenvalue Analysismentioning

confidence: 99%

A numerical model for the scattering of elastic waves from a non-axisymmetric defect in a pipe

Duan

Kirby

2015

Finite Elements in Analysis and Design

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Ultrasonic guided waves are used in the non-destructive testing of pipelines. This involves launching an elastic wave along the wall of the pipe and then capturing the returning wave scattered by a defect. Numerical study of wave scattering is often computationally expensive because the shortest wavelength is often very small compared to the size of the pipe in the ultrasonic frequency range. Furthermore, the number of the scattered wave modes from a non-axisymmetric defect in the pipe can be large and separation of these modes is difficult in a conventional finite element method. Accordingly, this article presents a model suitable for studying elastic wave propagation in waveguides with an arbitrary cross-section in the time and frequency domain. A weighted residual formulation is used to deliver an efficient hybrid numerical formulation, which is applied to a long pipeline containing a defect of arbitrary shape. The problem is solved first in the frequency domain and then extended to the time domain using an inverse Fourier transform. To separate the scattered wave modes in the time domain, a technique is proposed whereby measurement locations are arranged axially along the pipe and a two dimensional Fourier transform is used to present data in the wavenumberfrequency domain. This enables the separation of highly dispersive modes and the recovery of modal amplitudes. This has the potential to reveal more information about the characteristics of a defect and so may help in distinguishing between different type of defects, such a cracks or regions of corrosion, typically found in pipelines.3

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“…[9][10][11][12][13] As an example, consider the extended Hamilton's principle for an anisotropic elastic solid…”

Section: Safe Approachmentioning

confidence: 99%

“…The eigenvalues can be obtained by standard procedures. [10][11][12][13] The shape of the eigenmodes for the anisotropic waveguides with irregular cross section can be complex, which stipulates the necessity of the mode analysis and filtering, etc. The description of some of the ideas of the spectrum analysis can be found in Refs.…”

Section: Safe Approachmentioning

confidence: 99%

Repulsion of dispersion curves of quasidipole modes of anisotropic waveguides studied by finite element method

Zharnikov

Syresin²

2015

The Journal of the Acoustical Society of America

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In this letter repulsion of phase-velocity dispersion curves of quasidipole eigenmodes of waveguides with non-circular cross section in non-axisymmetric anisotropic medium is studied by the semi-analytical finite element technique. Borehole waveguide is used as an example. The modeling helps in clarifying the nature of this phenomenon, which is accompanied by the rotation of the orientation of two quasidipole modes with frequency and by the exchange of their behavior at near-crossover point. The dispersion curves cross only in the presence of exact symmetry. Such a scenario is the alternative to the stress-induced anisotropy crossing of dispersion curves.

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Numerical and analytical calculation of modal excitability for elastic wave generation in lossy waveguides

Cited by 30 publications

References 42 publications

Temporal behavior of laser induced elastic plate resonances

Temporal behavior of laser induced elastic plate resonances

A numerical model for the scattering of elastic waves from a non-axisymmetric defect in a pipe

Repulsion of dispersion curves of quasidipole modes of anisotropic waveguides studied by finite element method

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