Amplitude Dependence of the Internal Friction and Modulus Defect in Aluminium I. Measuring Methods

If a mechanical resonator consisting of a sample and two end load masses is electro-dynamically excited into longitudinal vibration then damping modulus defect, and oscillation amplitude can be measured automatically in a bridge circuit (1 kc/s to 10 kc/s). This method is combined with simultaneous ultrasound pulse measurements which give a “snapshot” of the stress state caused by the kilocycle oscillations.