Modeling wave propagation in damped waveguides of arbitrary cross-section

Bartoli, Ivan; Marzani, Alessandro; Matt, Howard; Scalea, Francesco Lanza di; Viola, Erasmo

doi:10.1117/12.640032

Cited by 147 publications

(193 citation statements)

References 35 publications

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“…It is shown in Fig. 4.b that two of the symmetric modes, labelled as B and C, cross at roughly 0.50 MHz, a similar result was obtained and discussed in figure 5 of [7] for a different monoclinic plate. Note that the modes labelled A and B do not cross.…”

Section: Solutions For Systems In Flat Geometrysupporting

confidence: 69%

“…However, cases where high values of attenuation are present and arbitrary anisotropy in single or multi-layered structures is considered have been hardly studied due to the great difficulties encountered when computing their dispersion curves. For instance, dispersion curves for viscoelastic monoclinic plates have been found and, for low values of the attenuation, presented in two dimensional plots [7], but in general, a better understanding of the nature of the modes, and a clearer visualization of the solutions, is achieved when dispersion loci are reliably found for low as well as high values of attenuation and therefore dispersion curves are required in three dimensions.…”

Section: Introductionmentioning

confidence: 99%

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Full 3D dispersion curve solutions for guided waves in generally anisotropic media

Quintanilla

Lowe

2016

Journal of Sound and Vibration

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Dispersion curves of guided waves provide valuable information about the physical and elastic properties of waves propagating within a given waveguide structure. Algorithms to accurately compute these curves are an essential tool for engineers working in non-destructive evaluation and for scientists studying wave phenomena. Dispersion curves are typically computed for low or zero attenuation and presented in two or three dimensional plots. The former do not always provide a clear and complete picture of the dispersion loci and the latter are very difficult to obtain when high values of attenuation are involved and arbitrary anisotropy is considered in single or multi-layered systems. As a consequence, drawing correct and reliable conclusions is a challenging task in the modern applications that often utilise multi-layered anisotropic viscoelastic materials. These challenges are overcome here by using a spectral collocation method (SCM) to robustly find dispersion curves in the most complicated cases of high attenuation and arbitrary anisotropy. Solutions are then plotted in three-dimensional frequency-complex wavenumber space, thus gaining much deeper insight into the nature of these problems. The cases studied range from classical examples, which validate this approach, to new ones involving materials up to the most general triclinic class for both flat and cylindrical geometry in multi-layered systems. The apparent crossing of modes within the same symmetry family in viscoelastic media is also explained and clarified by the results. Finally, the consequences of the centre of symmetry, present in every crystal class, on the solutions are discussed.0 Accepted for publication in the Journal of Sound and Vibration,

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Section: Solutions For Systems In Flat Geometrysupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Full 3D dispersion curve solutions for guided waves in generally anisotropic media

Quintanilla

Lowe

2016

Journal of Sound and Vibration

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“…In view of the problems with root finding, recent work has focussed on using numerical techniques such as the finite element method to locate the roots of the governing dispersion relation. For example, Bartoli et al [4] use the finite element method to solve the dispersion relation for a waveguide of arbitrary cross-section, as well as for a viscoelastic plate. Bartoli et al also provide a detailed discussion on the background to this finite element based method, which is referred to in the elastic waveguide literature as the Semi Analytic Finite Element (SAFE) method.…”

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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“…The method yields results with ringing responses due to the cut-on frequencies of propagating modes. The effect of cut-on frequencies can be solved by adding damping to the waveguide [4,5] or alternatively by filtering out the cut-on frequency points, where the group velocity curve becomes pseudo-vertical [6]. In this paper, it was decided to avoid the existence of cut-on frequencies within the analysis frequency range.…”

Section: Introductionmentioning

confidence: 99%

SAFE-3D analysis of a piezoelectric transducer to excite guided waves in a rail web

Ramatlo¹,

Long²,

Loveday³

et al. 2016

AIP Conference Proceedings

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Abstract. Our existing Ultrasonic Broken Rail Detection system detects complete breaks and primarily uses a propagating mode with energy concentrated in the head of the rail. Previous experimental studies have demonstrated that a mode with energy concentrated in the head of the rail, is capable of detecting weld reflections at long distances. Exploiting a mode with energy concentrated in the web of the rail would allow us to effectively detect defects in the web of the rail and could also help to distinguish between reflections from welds and cracks. In this paper, we will demonstrate the analysis of a piezoelectric transducer attached to the rail web. The forced response at different frequencies is computed by the Semi-Analytical Finite Element (SAFE) method and compared to a full three-dimensional finite element method using ABAQUS. The SAFE method only requires the rail track cross-section to be meshed using two-dimensional elements. The ABAQUS model in turn requires a full three-dimensional discretisation of the rail track. The SAFE approach can yield poor predictions at cut-on frequencies associated with other modes in the rail. Problematic frequencies are identified and a suitable frequency range identified for transducer design. The forced response results of the two methods were found to be in good agreement with each other. We then use a previously developed SAFE-3D method to analyse a practical transducer over the selected frequency range. The results obtained from the SAFE-3D method are in good agreement with experimental measurements.

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Modeling wave propagation in damped waveguides of arbitrary cross-section

Cited by 147 publications

References 35 publications

Full 3D dispersion curve solutions for guided waves in generally anisotropic media

Full 3D dispersion curve solutions for guided waves in generally anisotropic media

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

SAFE-3D analysis of a piezoelectric transducer to excite guided waves in a rail web

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