Analysis of experimentally generated friction related acoustic emission signals

Acoustic emission signals generated by sliding friction between two flat steel surfaces are characterized. A test fixture to simulate the reciprocating motion between the two surfaces under controlled conditions is developed. Sliding friction under several combinations of surface roughness, relative velocity, and normal pressure was examined. Wideband AE sensors and instrumentation were used for acquiring and analyzing the acoustic emission signals. Acoustic emission events occurred primarily during the slip portion of the stick-slip cycles. AE waveform features obtained during these experiments were indicative of the tribological conditions. Frequency components in excess of 700 kHz were seen during these experiments. The characteristics of the experimentally observed acoustic emission signals were in general agreement with earlier numerical predictions. Friction related acoustic emission signals were distinguishable from those from other sources such as fatigue crack growth. The characterization of friction related acoustic emission signals is likely to be of value in many tribological and structural health monitoring applications.