Low frequency axisymmetric longitudinal guided waves in eccentric annular cylinders

Abstract

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.

Effect of Conical Profile on the Transmission of Elastic Waves From Cylindrical Waveguide to Bulk

“…Quadrilateral unit elements were considered for finite element analysis, the unit element size was being kept between λ/12 and λ/24, and the step time was taken as 2e-9. These were set to satisfy the Blake's and CFL (Courant-Friedrichs-Lewy) criterion for mesh size and time-stepping, respectively [14][15][16].…”

Semi-analytical finite-element modeling approach for guided wave assessment of mechanical degradation in bones

“…In this paper, we use the SAFE approach presented by Predoi et al ( 2007 ) and Castaings and Lowe ( 2008 ). The procedure, given in some detail in our prior publications in the general context of guided ultrasound in complex media (see Pattanayak et al 2015 ; Ramdhas et al 2015 ; Manogharan et al 2016 ), is briefly outlined below.…”

Feature-guided wave-based health monitoring of bent plates using fiber Bragg gratings

“…Recently, the above challenge has been addressed using ultrasonic guided waves confined to locally extended features such as welds, bends, thinning or thickening regions (Fan and Lowe, 2009, 2012; Pattanayak et al, 2015; Rajagopal and Pattanayak, 2015; Ramdhas et al, 2013). Such confined elastic waves are now more commonly referred to as ‘feature-guided waves’ (FGW) (Lawrie and Kaplunov, 2012).…”