Apparatus for Measuring Internal Friction and Modulus Changes of Metals at Low Frequencies

Abstract

A description is given of a torsion pendulum and associated apparatus which have been employed in measuring internal friction and modulus changes due to dislocations. The pendulum is contained in an evacuated chamber. One specimen chamber is used for temperatures between 80° and 400°K and another for the range 290° to 1000°K. Decrements above 4×10⁻⁵ have been observed at maximum strain amplitudes in the range 2×10⁻⁷ to 2×10⁻⁴. Modulus changes may be measured within 1 part in 10⁴. The specimens may be plastically deformed in situ at temperature. A method is described for making measurements with an elastic torsional bias stress on the specimen.