Lamb Wave Based Damage Detection and Localization Using Two Ring-Shaped Arrangement of Piezo Transducers

Abstract

The damage monitoring on flexible mechanical structures requires digital signal processing algorithms and interpretation methods, which aim to extract parameters sensitive to the rise of discontinuities in the material from the measurements, in order to classify signal events to detect the onset of damage. This paper proposes a simple and effective methodology, based on Lamb wave, analyzing signals generated by a double ring-shaped arrangement of piezoelectric transducers. These signals are processed by discrete wavelet and Hilbert transform, intended to improve peak amplitude and phase estimation, through noise and dispersion reduction. Assessment of structure's integrity proceeds through the joint analysis of damage indices calculated from the discrepancy of the maximum amplitude of the signal measured by each sensor of the arrangement. Experimental application of the method to an aluminum plate showed its effectiveness to detect and localize damages in established regions of the monitored area, including the case two simultaneous damages.