Symmetric low-frequency feature-guided ultrasonic waves in thin plates with transverse bends

Ramdhas, Abilasha; Pattanayak, Roson Kumar; Balasubramaniam, Krishnan; Rajagopal, Prabhu

doi:10.1016/j.ultras.2014.07.014

Cited by 40 publications

(33 citation statements)

References 42 publications

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“…44 and 45). A competing mechanism for mode confinement due to velocity changes in flatter regions of eccentric pipes, similar to feature-guiding effects noted recently 39,46,47 is also revealed in a set of further studies considering more general pipe radius-thickness ratio and eccentricity cases. This paper is organized as follows.…”

Section: Introductionsupporting

confidence: 78%

“…V B above: the L mode is expected to get focused in the region of increased curvature (thinner region). In addition, we note with much interest, in the thicker part of the pipe, the physics is similar to feature guided wave (FGW) effect noted in the literature and also recently by Ramdhas et al 46,47 Briefly, for FGW phenomena to occur, the velocity of a mode of interest in a local feature must be lower than the velocity in the surrounding region. The L(0,2) mode in pipes is similar to the S0 mode in plates 15 where its velocity decreases with increasing plate thickness.…”

Section: Mode Focusing Effects At Other Radius-thickness Valuessupporting

confidence: 72%

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Low frequency axisymmetric longitudinal guided waves in eccentric annular cylinders

Pattanayak

Manogharan

Balasubramaniam

et al. 2015

The Journal of the Acoustical Society of America

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This paper studies the effect of axially uniform eccentricity on the modal structures and velocities of the lower order axisymmetric guided wave mode L(0,2) in circular tubes or pipes. The semi-analytical finite element method is mainly used, supported by fully three-dimensional finite element models and validated using experiments. The studies show that even a small eccentricity in the pipe can cause a loss in the L(0,2) mode axisymmetry, leading to its confinement in the thinned side of the pipe cross-section and also a reduction in mode velocities. The physics of this phenomenon is related to the feature-guiding and mode confinement effects noted in recent years in the literature, particularly studies on waveguides with local cross-section variations and curvature.

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Section: Introductionsupporting

confidence: 78%

Section: Mode Focusing Effects At Other Radius-thickness Valuessupporting

confidence: 72%

Low frequency axisymmetric longitudinal guided waves in eccentric annular cylinders

Pattanayak

Manogharan

Balasubramaniam

et al. 2015

The Journal of the Acoustical Society of America

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“…Such an effect is closely related to feature-guided wave phenomena noted in the literature in recent years. 3,7,8 Also an interesting observation is that pipe eccentricity does not seem to affect the T(0,1) mode as strongly, and its modal structure and nondispersive nature are very similar to the circular pipe even in cases of high ovalness. This paper is organized as follows.…”

Section: Introductionmentioning

confidence: 94%

“…3,7,8 Recent analytical studies (Postnova and Craster 11,12 ) have shown that curvature effects in waveguides are mathematically equivalent to local thinning. Again drawing upon the work of Postnova and Craster, 11,12 we find that for longitudinal modes, trapping is only possible for local thinning for Poisson ratio in the range of metals.…”

Section: Understanding the Physics Of Mode Focusing Based On Literaturementioning

confidence: 99%

Ultrasonic guided waves in elliptical annular cylinders

Rajagopal¹,

Pattanayak²

2015

The Journal of the Acoustical Society of America

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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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“…The main challenge to the inspection of composites is the presence of multiple layers and anisotropic nature. Ultrasonic guided waves have been proven an attractive tool in inspection of large structures [2][3][4][5]. PZT and Fiber Bragg Gratings based sensors have been embedded often to monitor the crack growth during the curing process [6].…”

Section: Introductionmentioning

confidence: 99%