Journal ArticleDOI
On the use of absorbing layers to simulate the propagation of elastic waves in unbounded isotropic media using commercially available Finite Element packages
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TLDR
In this article, the authors address methods to dramatically enhance computational efficiency by only meshing a local region of the material surrounding the defect; this reduction requires some kind of boundary, or boundary condition, which absorbs, rather than reflects, any waves arriving at the exterior of the modeled domain.Abstract:
Finite Element models for simulating wave propagation and scattering from defects are vital for ultrasonic methods in NDE. This article addresses methods to dramatically enhance computational efficiency by only meshing a local region of the material surrounding the defect; this reduction requires some kind of boundary, or boundary condition, which absorbs, rather than reflects, any waves arriving at the exterior of the modelled domain. A variety of approaches exist and we take two approaches, Perfectly Matched Layers (PML) and Absorbing Regions, selected specifically as they are readily implemented in commercially available Finite Element packages without requiring the source code. We illustrate both bulk and guided waves, and analysis is used to guide the performance, and thus to plan the use, of each of them. Finally, application examples illustrate the gains yielded by absorbing layer methods in terms of reducing both model size and unwanted reflections.read more
Citations
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Journal ArticleDOI
Implementation of the novel perfectly matched layer element for elastodynamic problems in time-domain finite element method
TL;DR: In this paper , a novel element is derived to deal with absorbing boundary conditions in the framework of time-domain finite element method (TDFEM), which combines with the viscoelastic model and modified Newmark algorithm to absorb outgoing waves in unbounded domains.
Journal ArticleDOI
Diffusely scattered and transmitted elastic waves by random rough solid-solid interfaces using an elastodynamic Kirchhoff approximation
TL;DR: In this paper, the authors introduce theoretical formulas for the diffuse field of elastic waves scattered by, and transmitted across, random rough solid-solid interfaces using the elastodynamic Kirchhoff approximation.
Journal ArticleDOI
Implementation of the novel perfectly matched layer element for elastodynamic problems in time-domain finite element method
TL;DR: In this paper, a novel element is derived to deal with absorbing boundary conditions in the framework of time-domain finite element method (TDFEM), which combines with the viscoelastic model and modified Newmark algorithm to absorb outgoing waves in unbounded domains.
Journal ArticleDOI
Recovery of correlation function of internal random rough surfaces from diffusely scattered elastic waves
TL;DR: In this article, an ultrasonic methodology is proposed to reconstruct the height correlation function of remotely inaccessible random rough surfaces in solids, which is based on the Kirchhoff approximation (KA) and requires measuring the angular distribution of diffuse scattering intensities by sending in a narrow band incident pulse near field scattering effects are also included by considering the Fresnel assumption.
Journal ArticleDOI
Bayesian synthesis for simulation-based generation of probability of detection (PoD) curves.
Mohamed Subair Syed Akbar Ali,Anish Kumar,Purnachandra B. Rao,Jayakumar Tammana,Krishnan Balasubramaniam,Prabhu Rajagopal +5 more
TL;DR: PoD curves generated using the proposed approach, where results from a reduced number of experimental defect cases and trials are used in combination with simulated datasets, are shown to compare well with those from the conventional approach using a large number of experiments.
References
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Journal ArticleDOI
A perfectly matched layer for the absorption of electromagnetic waves
TL;DR: Numerical experiments and numerical comparisons show that the PML technique works better than the others in all cases; using it allows to obtain a higher accuracy in some problems and a release of computational requirements in some others.
Journal ArticleDOI
Radiation boundary conditions for wave-like equations
Alvin Bayliss,Eli Turkel +1 more
TL;DR: In this article, a sequence of radiating boundary conditions is constructed for wave-like equations, and it is proved that as the artificial boundary is moved to infinity the solution approaches the solution of the infinite domain as O(r exp -m-1/2) for the m-th boundary condition.
Journal ArticleDOI
Matrix techniques for modeling ultrasonic waves in multilayered media
TL;DR: This paper presents a review of the main developments of the matrix techniques, and their use in response and modal models, with emphasis on ultrasonics applications.
Journal ArticleDOI
A two-dimensional Fourier transform method for the measurement of propagating multimode signals
D. N. Alleyne,Peter Cawley +1 more
TL;DR: In this article, a two-dimensional Fourier transform (2D FFT) was used to measure the amplitudes and velocities of the Lamb waves propagating in a plate, the output of the transform being presented using an isometric projection which gives a three-dimensional view of the wave-number dispersion curves.
Journal ArticleDOI
Radiation boundary conditions for acoustic and elastic wave calculations
Björn Engquist,Andrew Majda +1 more
TL;DR: In this article, a technique for developing radiating boundary conditions for artificial computational boundaries is described and applied to a class of problems typical in exploration seismology involving acoustic and elastic wave equations.
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