Ultrasonic guided waves in elliptical annular cylinders
23 Sep 2015-Journal of the Acoustical Society of America (Acoustical Society of America)-Vol. 138, Iss: 3
TL;DR: The studies reveal that even a small degree of ovalness can affect mode shapes and velocities in thin pipes, and this may be important for practical inspection applications.
Abstract: This paper studies the influence of cross-section ovalness or ellipticity on lower order axisymmetric guided wave modes in thin pipes. The second longitudinal mode L(0,2) and the fundamental torsional mode T(0,1) are studied, as these are of interest to current pipe inspection. The semi-analytical finite element (FE) method is mainly used, with three-dimensional FE simulations for visualization and cross-validation of results. The studies reveal that even a small degree of ovalness can affect mode shapes and velocities. The effect is more pronounced on the L(0,2) mode than on T(0,1) and this may be important for practical inspection applications.
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01 Jan 2018
TL;DR: In this article, a shear horizontal type bend-guided wave (SHB) mode has been identified, which is almost non-dispersive and non-leaky, with strong energy confinement in the bend region, which makes it attractive to be applied as a screening tool for composite bends.
Abstract: Complex-shaped composite laminates are increasingly utilized as Principal Structural Elements (PSE) such as spars, ribs, and the skin-stiffener combination in the aerospace industry. However, due to the stress concentration and out-of-plane impacts during the service life, various types of defects can be initiated in these structures, which have to be identified timely in case they propagate at subsurface laminae and ultimately lead to catastrophic failure. Therefore, this thesis explores the potential of exploiting a special type of ultrasonic guided wave, i.e. feature guided wave (FGW), for rapid screening of long-range composite structures. Such FGWs are capable of focusing their wave energy along the structural feature, with limited leakage into the adjacent plate. Two typical composite features are investigated in the thesis, which are laminated bends and adhesive composite joints, and the results are encouraging. Modal analysis of the laminated bend is carried out by using the Semi-Analytical Finite Element (SAFE) approach, in which the spatially-varying anisotropy is implemented to reveal the existing FGW modes. A shear horizontal type bend-guided (SHB) mode has been identified. The mode is almost non-dispersive and non-leaky, with strong energy confinement in the bend region, which is attractive to be applied as a screening tool for composite bends. Both 3D Finite Element (FE) simulations and experiments are performed to cross-validate the propagation characteristics of the SHB mode and to study its interaction with different defects occurred in the bend region, such as the interlaminar delamination and cracks, showing good agreement. The wave-defect resonance phenomenon and the reflection behaviour are investigated for localizing these two types of defects, and the capabilities of the SHB mode for efficient damage detection in long-range composite bends have been well demonstrated. Also, adhesive bonding is widely used in aerospace composites, and its integrity is crucial to the performance of the entire structure. This motivates the investigation of FGWs in another typical composite assembly, namely the stiffener-adhesive bond-
5 citations
Cites background from "Ultrasonic guided waves in elliptic..."
...The feature guiding phenomena have also been reported to exist in a wide range of geometries, such as the lap joint, the interconnected heat exchanger tube plate [56], structural bends [58,59], as well as in the eccentric and elliptical annular cylinders [112,113]....
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TL;DR: In this article , a 0-mode Lamb wave-based damage detection technique has been illustrated which can detect the overlapping region of incident and scattered wave in the vicinity of the finite defect region in CFRP composite plate-like structure.
4 citations
TL;DR: In this paper, the potential of higher frequency ultrasonic guided wave mode cluster (HOMC) waves to be used for remote inspection of notch defects in plate-like structures is investigated, at room and elevated temperatures.
Abstract: The potential of higher frequency ultrasonic guided wave mode cluster (HOMC) waves to be used for remote inspection of notch defects in plate-like structures is investigated, at room and elevated temperatures. Quantitative studies of HOMC interaction with notch defects ranging from 5% to 50% of plate thickness are performed using 2D finite element simulations, and are validated by controlled experiments performed, firstly at room temperature. Analysis using reciprocity-based relations is used to uncover for the first time, how the constituent modes of HOMC play a vital role in their scattering processes. Further experiments are used to show that the results are stable up to 300 C, thereby demonstrating the feasibility of short range higher-resolution remote inspection of notch defects using non-dispersive higher frequency mode clusters in industrial conditions.
3 citations
23 Apr 2017
TL;DR: In this article, the authors demonstrate a technique to monitor cross-sectional irregularities in pipes by detecting the feature-guided waves using fiber Bragg grating sensors, which is in good agreement with the results reported in elastic wave literature.
Abstract: Cross-sectional irregularities such as eccentricity are an important problem for pipe and tubing infrastructure. Recent work by the authors shows that such axially extended pipe irregularities can cause confinement and feature-guiding of lower order ultrasonic guided waves. In this paper, we demonstrate a technique to monitor such irregularities in pipes by detecting the feature-guided waves using fiber Bragg grating sensors. Our experimental results are in good agreement with the results reported in elastic wave literature.
2 citations
Cites result from "Ultrasonic guided waves in elliptic..."
...These results are consistent with those reported in the literature.(4,5)...
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References
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TL;DR: In this article, the authors provide a vision of ultrasonic guided wave inspection potential as we move forward into the new millennium and provide a brief description of the sensor and software technology that will make ultrasonic guidance wave inspection commonplace in the next century.
Abstract: Ultrasonic guided wave inspection is expanding rapidly to many different areas of manufacturing and in-service inspection. The purpose of this paper is to provide a vision of ultrasonic guided wave inspection potential aswe move forward into the new millennium. An increased understanding of the basic physics and wave mechanics associated with guided wave inspection has led to an increase in practical nondestructive evaluation and inspection problems. Some fundamental concepts and a number of different applications that are currently being considered will be presented in the paper along with a brief description of the sensor and software technology that will make ultrasonic guided wave inspection commonplace in the next century.
623 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: Instrumentation for long range, guided wave inspection of pipework is now commercially available and as discussed by the authors discusses the principles of the method and reviews the results of site experience, which was originally designed to work on pipes that were either un-coated or covered with, for example, epoxy paint.
Abstract: Instrumentation for long range, guided wave inspection of pipework is now commercially available. This paper discusses the principles of the method and reviews the results of site experience. The technique was originally designed to work on pipes that were either un-coated or covered with, for example, epoxy paint. Recent tests have shown promising results with more attenuative coatings and these are discussed.
165 citations
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.
147 citations
TL;DR: This paper presents an evolution of the semianalytical finite element method, and gives examples that illustrate new improvements and their importance for studying the propagation of waves along periodic structures of infinite width.
Abstract: The dispersion curves for guided waves have been of constant interest in the last decades, because they constitute the starting point for NDE ultrasonic applications. This paper presents an evolution of the semianalytical finite element method, and gives examples that illustrate new improvements and their importance for studying the propagation of waves along periodic structures of infinite width. Periodic boundary conditions are in fact used to model the infinite periodicity of the geometry in the direction normal to the direction of propagation. This method allows a complete investigation of the dispersion curves and of displacement ∕ stress fields for guided modes in anisotropic and absorbing periodic structures. Among other examples, that of a grooved aluminum plate is theoretically and experimentally investigated, indicating the presence of specific and original guided modes.
107 citations