| Sensors constructed with single-crystal PMN-30%PT, i.e. Pb(Mg 1/3Nb2/3)O3–PbTiO3, are developed in this paper for Structural Health Monitoring (SHM) of composite plates. Transducers manufactured from PMN-PT have a considerably higher d33 piezoelectric coefficient than that of traditional piezoelectric materials used for SHM, and could possibly lead to smaller embedded sensors, more resistant to damage throughout structure life. To determine the potential of surface bonded PMN-PT for this application, glass/epoxy composite specimens were created containing an embedded delamination initiator to expedite a single mode of failure. Two different piezoelectric materials were bonded to the surface of each specimen: PMN, the test material, was placed on one side of the specimen, while a traditional material, PZT-4 (Pb(ZrTi)O3), was placed on the other. A comparison of the ability of both materials to transmit and receive an ultrasonic pulse was conducted, with the received signal detected by both a second surface-bonded transducer constructed of the same material, as well as a laser Doppler vibrometer (LDV) analyzing the same location. This information was collected over the course of the life of each composite specimen as fatigue damage was induced at incremental increases in the number of cycles. The optimal frequency range, use as an actuator and receiver, as well as the ability to monitor fatigue damage with both sets of transducers is discussed, along with a comparison between the use of a LDV versus bonded receiver. |
