An Apparatus for Measurement of Extremely High Internal Friction

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Abstract
A simple torsion apparatus has been developed for measurement of extremely high internal friction by determining the angle by which strain lags behind the stress in forced cyclic vibration. The results of measurement were compared with torsion pendulum measurements using free decay method. The highest internal friction measured with this apparatus was 0.55. This apparatus can be used to measure internal friction at a constant given stress amplitude and at a constant frequency of vibration. The stress amplitude and frequency of vibration can easily be varied over a wide range. There is no theoretical limit to the lowest frequency of vibration that can be used with this apparatus. The feature that measurements can be made while the zero point is changing renders this apparatus very useful in the study of internal friction of freshly cold‐worked metals.