Use of the Piezoelectric Gauge for Internal Friction Measurements

The addition of an auxiliary quartz crystal to the usual composite piezoelectric resonator provides a convenient strain gauge, which simplifies the measurement procedure and permits the evaluation of amplitude dependent decrements over a wide range of strain amplitudes. A unique feature of the new procedure is that virtually instantaneous values of the decrement are obtained, thus bringing transient internal friction phenomena under observation. Mechanical resonance frequencies may be precisely determined for high as well as low decrement specimens. The numerical evaluation of terms is carried out for a recommended driver-gauge construction of 18.5° X-cut quartz bars.