Apparatus for the measurement of internal friction and dynamic Young's moduls at kilocycle frequencies

Electrostatic transducers are used to excite and detect longitudinal vibrations in a rod specimen clamped at its mid-point. The electronic circuit forms a regenerative loop in which oscillations occur at the resonance frequency of the specimen. A method of calculating the amplitude of the specimen oscillations is given. Measurements of the internal friction and dynamic Young's modulus, which can be made as a function of strain amplitude and temperature up to 500° C, are illustrated by some preliminary observations on beryllium.