ACOUSTIC-EMISSION SIGNAL-DETECTION BY CERAMIC POLYMER COMPOSITE PIEZOELECTRETS EMBEDDED IN GLASS-EPOXY LAMINATES/

Piezoelectric composites, consisting of a ferroelectric ceramic powder of calcium-modified lead titanate dispersed in two different polymer matrices, viz. from vinylidene fluoride trifluoroethylene and an epoxy , have been fabricated. The composites show a mixed connectivity struc ture, and the results of electromechanical characterization are given. Thin films of these materials have been incorporated into surface mou nted acoustic emission sensors and their frequency response and abilit y to detect plate waves, generated by a simulated acoustic emission so urce, has been examined. In situ transducers embedded into glass-reinf orced laminate plates have also been examined and have been shown suit able for acoustic emission sensors.