Rayleigh wave interaction with inhomogeneities—Part 1: Near surface cavity and inclusion

Abstract

The interaction of a Rayleigh pulse with a circular cavity and circular inclusion has been examined employing dynamic photoelasticity. The explosively generated R-pulse travels along the free boundary and is trapped in the ligament between the cavity and the free boundary with little energy propagating around the cavity. For cavities and inclusions at shallow depth below the free surface failure of the ligament occurs and most of the energy associated with the incident R-wave is converted b y diffraction into body and surface waves. The existence of a shadow zone on the downstream side of the circular cavity provides a means of identifying the location of the cavity which is nearly tangent to the surface b y e.g. ultrasonic inspection.

Visualization of Ultrasonic Waves in a Solid by Stroboscopic Photoelasticity and Image Processing Techniques

“…For these purposes, some visualization systems have been developed using photoelastic or schlieren method (1)(2)(3)(4)(5).…”

Laser dynamic photoelasticity and digital image analysis for nondestructive evaluation of surface and near surface flaws through ultrasonic spectroscopy

“…A linear shift was observed for the frequencies corresponding to peaks and cut-off points of the spatial frequency spectrums as the depth of defect was increased. This was in accordance with the results obtained from spectral analysis in conventional ultrasonic testing as described before.Figure 2.9 represents the spatial frequency spectrums for surface slots of different depths andFigure 2.10 shows the variation of the corresponding cut-off wavelengths with respect to slot depths[7,8].Rossmanith and Dally examined the interaction of a Rayleigh wave with a circular inclusion using dynamic photoelasticity[25]. The inclusion was placed nearly tangent to the surface.…”