Development of Repetition Impact Tester and its Application

In order to investigate elastic or plastic deformation process of metals or other materials, an accurate impact test rig was developed. It consists of a gas bearing and a spindle as a hammer in order to minimize the effect of friction and increase the accuracy of measurement. Unlike the Shore rebound scleroscope, the impact hammer of the rig is free from restriction and allows natural rebounds, which provides more information from experiments such as variation of the coefficient of constitution with increment of impact times. Behavior of the hammer is measured with a laser Doppler vibrometer and a proximity sensor. By means of this rig, the deformation process from an elastic to plastic region within less than 0.5 ms was studied and a simple linear relationship between displacement and contact force was found. The effect of surface condition or bolted joint condition on rebounding behavior was also studied. From these experiments it was confirmed that this impact tester is useful for the investigation of tribological phenomena.