Application of Ferroelectric Ceramic/Polymer Composites for Detection of Acoustic Emission in Composite Plate Structures

摘要

Most commercially available acoustic emission sensors employ the piezoelectric properties of a ferroelectric ceramic e.g.. PZT, the majority of these being resonant transducers with resonant frequencies of a few kHz. Acoustic emission frequencies are predominantly in the range of a few kHz to 1MHz. Ultrasonic transducers with resonant frequencies of a few MHz are wideband sensors when used in this range. All these sensors measure the displacement of the surface of the structure under test. Work has been done to compare sensors constructed from piezoelectric composites consisting of ceramic particles embedded in a polymer matrix. These materials have been fabricated into surface mounted acoustic emission transducer and directly compared to the commercially available transducers. The obvious advantage of a piezoelectric element consisting of a ceramic/polymer composite is that it can be made into very thin films (<50μm) which can then be embedded into laminate structures for in situ sensors. Preliminary investigations into the viability of embedded composite sensors have been performed.