The rapid monitoring of structures using interdigital Lamb wave transducers

The use of interdigital PVDF transducers for the quick inspection of large, plate-like structures is discussed. The transducers are designed to excite a particular Lamb mode in the structure, the region of the structure that is insonified being controlled by the transducer design. An example is given of the monitoring of an aluminium plate by a single, circular transducer operating in pulse-echo mode, the a 0 Lamb mode at a frequency of about 1 MHz being transmitted and received. The transducer is split into segments so that the angular location of a reflector can be defined, the radial location of the reflector being determined from the time of arrival of the echo.