Detection of cracks in plates using piezo-actuated Lamb waves

Abstract

In this paper, a comprehensive methodology for locating and determining the extent of linear cracks in homogeneous plates based on the time-of-flight analysis of Lamb wave propagation is proposed. Piezoelectric sensors and actuators (PZTs) placed on a square grid configuration are used to excite and receive direct and reflected waves. The actuation frequency, spacing of PZTs and length of the signal to analyze are first determined. The grid is used to sweep across the plate to identify the location of a crack, if there is one. Elliptical loci of possible crack positions are constructed based on the flight time of crack-reflected waves estimated using energy spectra from the Hilbert–Huang transform of the sensor signals. A detailed procedure for obtaining the ellipses is described, including the blind zones. After identifying the crack position, the crack orientation is determined by varying the positions of the PZTs and observing the strength of the energy peaks in the Hilbert spectra. This provides the basis for moving the PZTs to estimate the extent of the crack. Experimental results obtained using aluminum plates with through, half-through and concealed cracks showed that the proposed method is feasible and accurate.

Quantitative assessment of through-thickness crack size based on Lamb wave scattering in aluminium plates

“…On the other hand, it should also be noted that the position of P1 is intentionally selected to satisfy Snell's law [27] to obtain a maximal reflection coefficient. The incidence angle of Lamb waves relative to the crack has an important effect on the amplitude of scattered wave signals collected by fixed sensors.…”

A fast BEM for the analysis of damaged structures with bonded piezoelectric sensors

“…Lin and Yuan [10] proposed an analytical model for an isotropic plate with integrated piezoelectric actuators and sensors for Lamb wave-based SHM systems. The detection of cracks in plates through piezogenerated Lamb waves is studied by Tua et al [11], who considered several system parameters and proposed a methodology for locating and quantifying the extent of cracks. Fukunaga et al [12] developed a two-stage strategy for damage identification, using a limited number of piezoelectric devices.…”

Detection and localization of closely distributed damages via lamb wave sparse reconstruction

“…Lamb wave is considered as a promising tool for damage detection in plate and pipe-like structures, because it can propagate over a long distance with low attenuation and sensitive to small changes in structural property [1]. To visualize the damage intuitively in a two-dimensional image, Lamb wave imaging technique by using several piezoelectric discs is developed.…”