Comparison of Plain Piezoceramics and Inter-digital Transducer for Crack Detection in Plates

Abstract

The use of piezoceramics transducers (PZTs) for non-destructive evaluation (NDE) via Lamb waves has attracted significant attention recently in view of its favorable sensing and actuating characteristics. A comprehensive strategy to locate and trace the geometry of cracks in plates has been developed earlier using either plain piezoceramics or interdigital transducers (IDTs) based on time of flight analysis of incident and reflected waves. In this article, a comparison of the two techniques is presented based on results from laboratory experiments. Cracks of differing geometries, namely, linear crack, curved crack, and multiple cracks, on aluminum plates are considered. Comparisons of their detection capabilities are also made on a crack of fine width (220 μm) and cracks filled with impurities such as grease, araldite epoxy, metallic epoxy, and spray paint. Both techniques are applied in the case of weld where a notch is induced in the weld on an aluminum plate and the results obtained for the weld with and without the notch are compared. The results for all cases considered show that both the plain piezoceramics and IDT techniques can successfully detect and locate the cracks. Plain piezoceramics are able to provide accurate detection for linear, nonlinear, and piecewise linear cracks, and notch in weld. The geometries are traced with reasonable accuracy. However, IDT has been shown to be more accurate, procedurally simpler, and is an efficient alternative to plain piezoceramics.