Experimental study to investigate the tribological behavior of cylinder-piston ring using acoustic emission

Acoustic emission(AE) techniques have been applied to dynamic machinery in diagnosing various component faults because of the non-intrusive technique. This work utilized cylinder-piston ring specimens as study objects, and explored basic properties of AE signals measured on a reciprocating rig. The local root mean square(RMS) and absolute energy values, which were averaged over a period time to obtain mean values in the crank angle domain, were extracted to investigate AE signals sensitivity to various operating conditions. Speeds, acceleration, loads, and lubrication states were considered as the influence factors. The results revealed that larger values of the AE signals were obtained with increasing velocity in a reciprocating circle where the increasing rate in acceleration process was higher than that in the deceleration process. However, with growing revolution speeds under oil lubrication condition, the maximum values of the AE signals of each circle experienced an increasing trend before a declining trend. Furthermore, the scuffing position could be diagnosed by the abrupt change of AE signal values after lubrication stopped for a period. It was therefore demonstrated that lubrication and friction states could be monitored by the AE signals.