A METHOD FOR MEASURING STATIC PRESSURE DEPENDENCE OF PIEZOELECTRIC PROPERTIES OF ULTRASONIC TRANSDUCER MATERIAL IN A SMALL PRESSURE TANK

Abstract

The motional admittance or impedance method cannot be applied to a test transducer material contained in a small non-sound-absorbing pressure tank, because the admittance or impedance locus does not make a circle due to the sound reflection at the tank wall. The method used is to excite a bar-shaped test piece in a pressure tank into longitudinal vibration by the use of a mechanical driving system, and to observe short-circuit current or open-circuit voltage of the test piece. A transducer material for high power use was taken as a sample. Piezoelectric constants e₃₁, h₃₁ and dielectric constant ε^s₃₃ were measured at hydrostatic pressures from 1 to 600 kg/cm². Vibrational velocity dependence of e₃₁ and h₃₁ was also measured, varying driving velocity level at the test piece end as high as 80 cm/s. The results are that e₃₁, h₃₁ and ε^s₃₃, become gradually large as hydrostatic pressure increases but show no appreciable velocity level dependence.