The scattering of guided waves in partly embedded cylindrical structures

Vogt, Thomas; Lowe, M. J. S.; Cawley, P.

doi:10.1121/1.1553463

Cited by 41 publications

(53 citation statements)

References 21 publications

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“…For example, Engan [18] used mode matching to study elastic wave propagation in a rod, Hayashi [10] and Demma et al [19] studied steps and notches in a plate, and mode matching was applied to a pipe by Ditri and Rose [20] and Vogt et al [21]. For the hybrid method, relevant examples include Predoi et al [15] and Imhof [22], who studied elastic wave propagation in plates; the scattering from non uniform defects in pipes is examined by Hayashi [10], Zhuang et al, [23], Bai et al [24] and Zhou et al [25].…”

Section: Introductionmentioning

confidence: 99%

On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

Kirby

Zlatev

Mudge³

2012

Journal of Sound and Vibration

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Long range ultrasonic testing is now a well established method for examining in-service degradation in pipelines. In order to protect pipelines from the surrounding environment it is common for viscoelastic coatings to be applied to the outer surface. These coatings are, however, known to impact on the ability of long range ultrasonic techniques to locate degradation, or defects, within a coated pipe. The coating dissipates sound energy travelling along the pipe, attenuating both the incident and reflected signals making responses from defects difficult to detect. This article aims to investigate the influence of a viscoelastic coating on the ability of long range ultrasonic testing to detect a defect in an axisymmetric pipe. The article focuses on understanding the behaviour of the fundamental torsional mode and quantifying the effect of bitumen coatings on reflection coefficients generated by axisymmetric defects. Reflection coefficients are measured experimentally for coated and uncoated pipes and compared to theoretical predictions generated using numerical mode matching and a hybrid finite element technique. Good agreement between prediction and measurement is observed for uncoated pipes, and it is shown that the theoretical methods presented here are fast and efficient making them suitable for studying long pipe runs. However, when studying coated pipes agreement between theory and prediction is observed to be poor for predictions based on those bulk acoustic properties currently reported in the literature for bitumen. Good agreement is observed only after conducting a parametric study to identify more appropriate values for the bulk acoustic properties. Furthermore, the reflection coefficients obtained for the fundamental torsional mode in a coated pipe show that significant sound attenuation is present over relatively short lengths of coating, thus quantifying those problems commonly encountered with the use of long range ultrasonic testing on coated pipes in the field.3

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Section: Introductionmentioning

confidence: 99%

On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

Kirby

Zlatev

Mudge³

2012

Journal of Sound and Vibration

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“…However, for completeness, relevant examples of the SAFE method may be found in refs. [11][12][13][14][15], for the mode matching method in [16][17][18], and for the hybrid method [19][20][21][22]. Here, the numerical methods applied to elastic wave propagation are generally based on the use of commercial software, which causes some problems when it comes to identifying the appropriate viscoelastic material properties suitable for the generic mass and stiffness matrices typically specified by commercial codes.…”

Section: Introductionmentioning

confidence: 99%

On the scattering of longitudinal elastic waves from axisymmetric defects in coated pipes

Kirby

Zlatev

Mudge³

2013

Journal of Sound and Vibration

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Viscoelastic coatings are widely used to protect pipelines from their surrounding environment.These coatings are known to attenuate ultrasonic waves guided along the pipe walls, which may limit the range of a pulse/echo based inspection technique that seeks to detect defects in a pipeline. This article aims to investigate the attenuation of longitudinal modes in a coated pipe by comparing predicted and measured values for the reflection coefficient of an axisymmetric defect in a pipe coated with bitumen. This extends recent work undertaken by the authors for torsional modes, and also provides an independent investigation into the validity of those values proposed by the authors for the shear properties of bitumen, based on a comparison between prediction and experiment for torsional modes. Predictions are generated using a numerical mode matching approach for axially uniform defects, and a hybrid finite element based method for non-uniform defects. Values for the shear and longitudinal properties of bitumen are investigated and it is shown that the shear properties of the viscoelastic material play a dominant role in the propagation of longitudinal modes in a coated pipeline. Moreover, by using the shear values obtained from experiments on torsional modes, it is shown that good agreement between prediction and measurement for uniform and non-uniform defects may also be obtained for the longitudinal L(0,2) mode. This provides further validation for the shear bulk acoustic properties proposed for bitumen in the low ultrasonic frequency range, although in order to apply this methodology in general it is demonstrated that one must measure independently the reflection coefficient of both the torsional T(0,1) and the longitudinal L(0,2) mode before arriving at values for the shear properties of a viscoelastic material.3

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“…The results show that almost no signal was transmitted through the 0.9 m long embedding region due to strong attenuation of the signal. The reflection coefficient is in the range of 0.1-0.22 and decreases with increasing frequency; this behaviour has been discussed in Vogt et al 20,21 Figure 4(c) shows results obtained in the half-wall case, where the transmitted signal decreases only slightly with propagation distance along the embedded region of the pipe and a significant signal was recorded at the monitoring position beyond the embedded region. The reflection coefficient in the half-wall case [ Fig.…”

Section: A Finite-element Simulationsmentioning

confidence: 61%

“…), and have been utilised to study various systems, including steel bars embedded in cement grout, 19 wires embedded in epoxy resin, 20,21 rock bolts embedded in rock strata, 22 reinforcing bars and anchor bolts embedded in concrete, 23 steel bars embedded in soil, 24 and pipes buried in sand. 5 Recently, Leinov et al 6 have presented the possibility of ultrasonic isolation of pipelines buried in soil, utilising a carefully specified pipe coating material promoting the trapping of ultrasonic guided wave energy within the waveguide rather than allowing it to leak.…”

mentioning

confidence: 99%

Investigation of guided wave propagation in pipes fully and partially embedded in concrete

Leinov

Lowe

Cawley

2016

The Journal of the Acoustical Society of America

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The application of long-range guided-wave testing to pipes embedded in concrete results in unpredictable test-ranges. The influence of the circumferential extent of the embedding-concrete around a steel pipe on the guided wave propagation is investigated. An analytical model is used to study the axisymmetric fully embedded pipe case, while explicit finite-element and semi-analytical finite-element simulations are utilised to investigate a partially embedded pipe. Model predictions and simulations are compared with full-scale guided-wave tests. The transmission-loss of the T(0,1)-mode in an 8 in. steel pipe fully embedded over an axial length of 0.4 m is found to be in the range of 32–36 dB while it reduces by a factor of 5 when only 50% of the circumference is embedded. The transmission-loss in a fully embedded pipe is mainly due to attenuation in the embedded section while in a partially embedded pipe it depend strongly on the extent of mode-conversion at entry to the embedded-section; low loss modes with energy concentrated in the region of the circumference not-covered with concrete have been identified. The results show that in a fully embedded pipe, inspection beyond a short distance will not be possible, whereas when the concrete is debonded over a fraction of the pipe circumference, inspection of substantially longer lengths may be possible.

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The scattering of guided waves in partly embedded cylindrical structures

Cited by 41 publications

References 21 publications

On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

On the scattering of torsional elastic waves from axisymmetric defects in coated pipes

On the scattering of longitudinal elastic waves from axisymmetric defects in coated pipes

Investigation of guided wave propagation in pipes fully and partially embedded in concrete

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