Finite element model for waves guided along solid systems of arbitrary section coupled to infinite solid media.
01 Feb 2008-Journal of the Acoustical Society of America (Acoustical Society of America)-Vol. 123, Iss: 2, pp 696-708
TL;DR: The paper presents the principles of a procedure and then validates and illustrates its use on some examples, and makes use of absorbing regions of material at the exterior bounds of the discretized domain.
Abstract: The Semi-Analytical Finite Element (SAFE) method is becoming established as a convenient method to calculate the properties of waves which may propagate in a waveguide which has arbitrary cross-sectional shape but which is invariant in the propagation direction. A number of researchers have reported work relating to lossless elastic waves, and recently the solutions for nonpropagating waves in elastic guides and for complex waves in viscoelastic guides have been presented. This paper presents a further development, addressing the problem of attenuating waves in which the attenuation is caused by leakage from the waveguide into a surrounding material. This has broad relevance to many practical problems in which a waveguide is immersed in a fluid or embedded in a solid. The paper presents the principles of a procedure and then validates and illustrates its use on some examples. The procedure makes use of absorbing regions of material at the exterior bounds of the discretized domain.
Citations
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TL;DR: In this paper, the attenuation characteristics of the T(0,1) and L (0,2) guided wave modes over a range of sand conditions, including loose, compacted, mechanically compacted and water saturated, were investigated using a laboratory full-scale experimental rig and model predictions.
129 citations
Cites background from "Finite element model for waves guid..."
...Castaings and Lowe [29] studied arbitrary section waveguides embedded in solid media....
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TL;DR: In this paper, a two-dimensional semi-analytical finite element (SAFE) method is applied to provide a modal study of the elastic waves that are guided by the welded joint in a plate.
Abstract: The inspection of large areas of complex structures is a growing interest for industry. An experimental observation on a large welded plate found that the weld can concentrate and guide the energy of a guided wave travelling along the direction of the weld. This is attractive for non-destructive evaluation (NDE) since it offers the potential to quickly inspect for defects such as cracking or corrosion along long lengths of welds. In this paper, a two-dimensional semi-analytical finite-element (SAFE) method is applied to provide a modal study of the elastic waves that are guided by the welded joint in a plate. This brings understanding to the compression wave that was previously observed in the experiment. However, during the study, a shear weld-guided mode, which is non-leaky and almost non-dispersive, has also been discovered. Its characteristics are particularly attractive for NDE, so this is a significant new finding. The properties for both the compression and the shear mode are discussed and compared, and the physical reason for the energy trapping phenomena is then explained. Experiments have been undertaken to validate the existence of the shear weld-guided mode and the accuracy of the FE model, showing very good results.
75 citations
Cites background or methods from "Finite element model for waves guid..."
...…of the absorbing regions has been chosen to be 800 mm, which is twice the biggest wavelength of any radiated wave in the whole frequency range (Castaings & Lowe 2008), and was proven to be efficient by a convergence check: when the length was increased, the same solutions for the propagating…...
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...A similar phenomenon has also been observed by Castaings & Lowe (2008) who showed that it can be explained by studying the normalized energy flow through the weld–plate interface that shows a similar curve....
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...In order to model the wave propagation along the weld and leaking into the side plates, an absorbing region has been attached at each side of the plate to avoid reflections from the edges (Castaings & Lowe 2008)....
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...Recently, the SAFE method has been developed by Castaings & Lowe (2008) to study leaky waves that propagate along an elastic waveguide with arbitrary cross section and radiate into a solid of infinite extent....
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TL;DR: This paper aims to provide an overview of the experimental and simulation works focused on the detection, localisation and assessment of various defects in pipes by applying fast-screening guided ultrasonic wave techniques that have been used in the oil and gas industries over the past 20 years.
Abstract: This paper aims to provide an overview of the experimental and simulation works focused on the detection, localisation and assessment of various defects in pipes by applying fast-screening guided ultrasonic wave techniques that have been used in the oil and gas industries over the past 20 years. Major emphasis is placed on limitations, capabilities, defect detection in coated buried pipes under pressure and corrosion monitoring using different commercial guided wave (GW) systems, approaches to simulation techniques such as the finite element method (FEM), wave mode selection, excitation and collection, GW attenuation, signal processing and different types of GW transducers. The effects of defect parameters on reflection coefficients are also discussed in terms of different simulation studies and experimental verifications.
72 citations
Cites methods from "Finite element model for waves guid..."
...Using the SAFE technique, Lowe and Castaings [221] studied arbitrary section elastic waveguide problems whereby GWs might leak into infinite surrounding solid materials....
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TL;DR: A semianalytical finite element method is developed to model accurately the propagation velocity and leakage of guided waves along an immersed waveguide with arbitrary noncircular cross section and Experimental results obtained with a rectangular bar in a range of fluids show very good agreement with the theoretical predictions.
Abstract: Guided torsional waves in a bar with a noncircular cross section have been exploited by previous researchers to measure the density of fluids. However, due to the complexity of the wave behavior in the noncircular cross-sectional shape, the previous theory can only provide an approximate prediction; thus the accuracy of the measurement has been compromised. In this paper, a semianalytical finite element method is developed to model accurately the propagation velocity and leakage of guided waves along an immersed waveguide with arbitrary noncircular cross section. An accurate inverse model is then provided to measure the density of the fluid by measuring the change of the torsional wave speed. Experimental results obtained with a rectangular bar in a range of fluids show very good agreement with the theoretical predictions. Finally, the potentials to use the model for sensor optimization are discussed.
67 citations
TL;DR: A non-destructive, ultrasonic technique to evaluate the quality of bonds between substrates, consisting of the evaluation of the shear stiffness modulus of a bond layer at different curing times between a metallic plate and a composite patch, being investigated in the context of repair of aeronautical structures.
Abstract: This paper presents a non-destructive, ultrasonic technique to evaluate the quality of bonds between substrates. Shear-horizontally polarized (SH) wave modes are investigated to infer the shear stiffness of bonds, which is necessarily linked to the shear resistance that is a critical parameter for bonded structures. Numerical simulations are run for selecting the most appropriate SH wave modes, i.e., with higher sensitivity to the bond than to other components, and experiments are made for generating-detecting pre-selected SH wave modes and for measuring their phase velocities. An inverse problem is finally solved, consisting of the evaluation of the shear stiffness modulus of a bond layer at different curing times between a metallic plate and a composite patch, such assembly being investigated in the context of repair of aeronautical structures.
63 citations
References
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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.
Abstract: Research into ultrasonic NDE techniques for the inspection of multilayered structures relies strongly on the use of modeling tools which calculate dispersion curves and reflection and transmission spectra. These predictions are essential to enable the best inspection strategies to be identified and their sensitivities to be evaluated. General purpose multilayer modeling tools may be developed from a number of matrix formulations which have evolved in the latter half of this century and there is now a formidable number of publications on the subject. 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. >
931 citations
TL;DR: In this article, a semi-analytical finite element (SAFE) method for modeling wave propagation in waveguides of arbitrary cross-section is proposed, and the dispersive solutions are obtained in terms of phase velocity, group velocity, energy velocity, attenuation and cross-sectional mode shapes.
534 citations
TL;DR: Theoretical and experimental issues of acquiring dispersion curves for bars of arbitrary cross-section for guided waves have great potential for being applied to the rapid non-destructive evaluation of large structures such as rails in the railroad industry.
512 citations
TL;DR: A method is presented by which the wavenumbers for a one-dimensional waveguide can be predicted from a finite element (FE) model, which involves postprocessing a conventional, but low order, FE model, the mass and stiffness matrices of which are typically found using a conventional FE package.
Abstract: A method is presented by which the wavenumbers for a one-dimensional waveguide can be predicted from a finite element (FE) model. The method involves postprocessing a conventional, but low order, FE model, the mass and stiffness matrices of which are typically found using a conventional FE package. This is in contrast to the most popular previous waveguide/FE approach, sometimes termed the spectral finite element approach, which requires new spectral element matrices to be developed. In the approach described here, a section of the waveguide is modeled using conventional FE software and the dynamic stiffness matrix formed. A periodicity condition is applied, the wavenumbers following from the eigensolution of the resulting transfer matrix. The method is described, estimation of wavenumbers, energy, and group velocity discussed, and numerical examples presented. These concern wave propagation in a beam and a simply supported plate strip, for which analytical solutions exist, and the more complex case of a viscoelastic laminate, which involves postprocessing an ANSYS FE model. The method is seen to yield accurate results for the wavenumbers and group velocities of both propagating and evanescent waves.
400 citations
TL;DR: In this paper, the dispersion curves of propagative waves in a free rail are computed by using triangular and quadrilateral finite elements of the cross-section of the waveguide.
352 citations