Effect of Surface Cracks on Rayleigh Wave Propagation: An Experimental Study

Abstract

This experimental study investigates the use of Rayleigh waves for crack detection in structural elements. Receiver arrays measure surface accelerations at various locations with respect to a vertical slot cut into a thin Plexiglas sheet. Two-dimensional Fourier transform calculations provide Rayleigh wave dispersion and energy with respect to various slot depths. In addition, autospectrum calculations aid in defining slot location. It is shown that slots reflect short wavelengths and allow the transmission of long wavelengths. Slot location is easily identified from autospectrum measurements; however, accurate determination of slot depth is dependent on the aperture function of the array.

Detection of Surface Breaking Cracks in Concrete Members Using Rayleigh Waves

“…The magnitude of the complex coefficients is calculated from the Fourier transformed matrix. Contouring the magnitude values produces a plot with a series of peaks that can be used to calculate dispersion curves for the measured propagating modes (Zerwer et al, 2000;Zerwer et al, 2002). The phase velocity for the different propagating modes can be computed from the frequency-wavenumber domain using:…”

“…This work is an extension of the tests and signal processing, described by Zerwer et al (2002), to detect the size and location of cracks in plexiglas plates simulating slices of beam-type elements. This work also builds on the ideas presented in the literature concerning Rayleigh wave screening in soils (R.K. Srivastava and N.S.V.…”

Thein-situevaluation of surface-breaking cracks in asphalt using a wave decomposition method

“…Particularly, the resonant effects of the scattering waves [20] or leaky Rayleigh waves [16] in the ultrasonic range of frequencies are exploited to extract the information about the depth and the length of a surface crack. Wave transmission, reflection and attenuation spectral ratios are often exploited by various authors for detection and sizing of surface discontinuities [7], [14], [24]- [27] , exploiting the resonant features of surface-breaking cracks. Spectral analysis of acoustic emission is also exploited by many for crack evaluation and localization [22]- [24], [28]- [30] .…”

Exploiting spectral differences between two acoustic imaging methods for the in situ evaluation of surface-breaking cracks in asphalt

“…Particularly, the resonant effects of the scattering waves [18] or leaky Rayleigh waves [14] in the ultrasonic range of frequencies are exploited to extract the information about the depth and the length of a surface crack, with ambiguous results. Wave transmission and attenuation measurements and the spectral ratio of the transmitted wave on the incident wave are also exploited by various authors for detection and sizing of surface discontinuities [3], [19], [20] .…”

“…Numerical approaches to surface-breaking discontinuity detection show that the dispersion curve, and hence the wavefield, changes if the signal travels across a vertical discontinuity, which can be a crack or a slot [21] . An investigation on a homogeneous Plexiglas sheet suggested the use of an array of sensors to compute the power spectral density for the location of the cracking, and the use of frequency-wavenumber spectral images obtained from the same array of sensors for the assessment of the crack depth [19] . Although the power spectral density showed to be sensitive to the crack location, the assessment of depth proved to be inaccurate.…”