Mechanical and electromechanical properties of calcium-modified lead titanate/poly(vinylidene fluoride-trifluoroethylene) 0-3 composites

Thin film composite sensors have been fabricated which incorporate piezoelectric ceramic particles in apolymer matrix. These composites are more compliant than pure piezoelectric ceramics and can beembedded in thick structures to monitor internal mechanical conditions, such as the evolution of damage. Composite films consisting of Ca-modified lead titanate particles in a poly(vinylidene fluoride- trifluoroethylene) matrix are examined in this paper. The viscoelastic properties of these composites (withvarious volume fractions, up to 60% ceramic) have been measured over a range of frequencies (0.01 to 100rad/sec). The complex h1 piezoelectric coefficient has also been measured for these composites for various volume fractions and over a frequency range from 5 to 100 rad/sec. The magnitudes and phase angles of thepiezoelectric coefficients are shown to be highly frequency dependent.Keywords: piezoelectric, composite, sensor, lead titanate, P(VDF-TrFE) 1. INTRODUCTION Much information regarding the mechanical status of a structure can be obtained through surface monitoringsensors such as strain gages. However, as thick polymeric composite structures become increasingly utilized,many mechanical issues (such as residual stresses and the progressive evolution of internal damage) would bebetter sensed from within the structure. Currently, embedded sensors are being used to detect stress waves in