Apparatus for the Measurement of the Internal Friction of Metals in Transverse Vibration

Abstract

Apparatus incorporating a specially designed piezoelectric pickup serving in turn as an exciter and detector is described for the measurement of the internal friction of vertically suspended specimens vibrating transversely in vacuo in the free‐free mode. Measurements have been made by the free‐decay method in the frequency range 5 cy/sec‐2 kc/sec, and at maximum strain‐amplitudes of 10⁻⁴−5×10⁻⁷. The method of frequency variation by loading with weights has been applied successfully to the fundamental vibration. Methods of investigating external energy losses are described, and results presented to show that the total external loss is small, rarely exceeding 5% of the observed internal friction.