Elastic shear wave scattering by randomly rough surfaces

Haslinger, S. G.; Lowe, M. J. S.; Huthwaite, Peter; Shi, Fan

doi:10.1016/j.jmps.2019.103852

Cited by 17 publications

(24 citation statements)

References 26 publications

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“…A comparison of Figure 8 in [3] and Figure 14 in [2] shows that the expected amplitude of the industry-adopted model of [3] is overly conservative by at least 20dB once roughness surpasses a specific threshold. This result was the motivation for the new theoretical model summarized here that includes elastic waves and all mode conversions [4][5][6][7][8].…”

mentioning

confidence: 85%

“…Note that we follow previous literature [6,7] in using two-dimensional space in this article to investigate a wider range of parameters owing to the increased computational efficiency; the equivalent definitions and expressions are provided in 3-dimensional space in [4,5]. In addition, the mechanisms that determine the limits of validity for KA are equivalent in 2D and 3D [17] and quasi-2D cracks are common in practice, for example in welds [18].…”

Section: Figurementioning

confidence: 98%

“…The model presented here is designed to be adopted within inspection qualification as an applicable theoretical model, having been validated by numerical and experimental methods for appropriate ranges of validity [4][5][6][7]. The model is versatile, being applicable for a range of inspection set-ups, such as pulse-echo (P-E) and pitch-catch, as well as including capability for the inclusion of tilt and skew angles.…”

Section: Section 2: Inspection Set-ups and Physical Propertiesmentioning

confidence: 99%

“…Here, we concentrate on determining expected amplitudes for specular and backscattered directions for a range of P-E set-ups that include tilted defects, as illustrated in Figure 3. As explained in detail in the publications [4][5][6][7], the new statistical elastodynamic scattering model applies a stationary phase method to the Kirchhoff approximation (KA) displacement term to derive expected diffuse intensity formulae for rough surfaces for any scattering direction. This universality improves on the estimate for diffuse intensity given in preceding work [3], where the diffuse term was calculated as an average over all scattering angles.…”

Section: Section 2: Inspection Set-ups and Physical Propertiesmentioning

confidence: 99%

“…where vw is termed the elastodynamic factor which, along with the phase term vw , depends on incident and scattering angles and material parameters. The full expressions and derivations for these roughness-independent terms are provided in [4] and [7]. The sum in ( 8) is such that is a relatively small integer ( = 20 is more than sufficient for the range of validity where the model applies).…”

Section: Coherent and Diffuse Fieldsmentioning

confidence: 99%

See 4 more Smart Citations

Prediction of reflection amplitudes for ultrasonic inspection of rough planar defects

Haslinger¹,

Lowe²,

Huthwaite³

et al. 2021

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The characteristics of planar defects (no loss of material volume) that arise during industrial plant operation are difficult to predict in detail, yet these can affect the performance of non-destructive testing (NDT) used to manage plant structural integrity. Inspection modelling is increasingly used to design and assess ultrasonic inspections of such plant items. While modelling of smooth planar defects is relatively mature and validated, issues have remained in the treatment of rough planar defect species. The qualification of ultrasonic inspections for such defects is presently very conservative, owing to the uncertainty of the amplitudes of rough surface reflections. Pragmatic solutions include the addition of large sensitivity thresholds and more frequent inspection intervals, which require more plant downtime. In this article, an alternative approach has been developed by the authors to predict the expected surface reflection from a rough defect using a theoretical statistical model. Given only the frequency, angle of incidence and two statistical parameter values used to characterise the defects, the expected reflection amplitude is obtained rapidly for any scattering angle and size of defect, for both compression and shear waves. The method is applicable for inspections of isotropic media that feature surface reflections such as pulse-echo or pitch-catch, rather than for tip signal-dependent techniques such as time-of-flight diffraction. The potential impact for inspection qualification is significant, with the new model predicting increases of up to 20 dB in signal amplitude in comparison with models presently used in industry. All mode conversions are included and rigorous validations using numerical and experimental methods have been performed. The model has been instrumental in obtaining new statistically significant results related to the effect of tilt; the expected pulse-echo backscattered amplitude for very rough planar defects is independent of tilt angle, with convergence obtained for a range of frequencies.

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