Piezo-transducer's shape design as a pre-processing tool in guided wave inspections

Structural health monitoring is an important task in several industrial applications. For example, passive-only networks of piezoelectric sensors can be exploited to detect and localize impacts or anomalous acoustic emissions for the early identification of crack initiation and growth from the analysis of the emitted ultrasonic guided waves. In this work, a shaped piezoelectric sensor and the dedicated electronics for guided wave detection on laminate composite and metallic structures is presented. This device is meant as a basic building block for the development of passive sensor networks in smart structure applications. Elastic waves propagating on the structure are recorded by the transducer composed by multiple, irregularly shaped electrodes and then processed by a microcontroller embedded on the sensor node. The irregular shaping of the transducer electrodes is exploited to simplify the signal processing procedures that are necessary to detect the wave direction of arrival.