Assessment of O-ring Seal Performance by Measurement of Acoustic Emission Signals

Abstract

O-rings are commonly installed in fluid systems for sealing purpose. There is ongoing research towards improving O-rings’ sealing performances by using adaptive elastomeric materials at the Department of Mechanical Engineering at University of Minnesota. As part of seal development the performance of the seal has to be assessed. In this research a test stand for measuring leakage was constructed and leakage measurement was demonstrated as the seal leakage was measured by Monitoring Acoustic Emission (AE) signals. The test stand was constructed in which a specified load or a specified displacement can be applied to an O-ring held between flat plates, high pressure air introduced to the inside of the seal and AE due to leakage measured. The scope of this research was to try to quantify leakage rate of in use O-ring as a function of AE signals. The AE signals were measured as a function of volumetric air flow rate Q, working fluid pressure P, O-ring counterface force F and seal AE sensor distance d. Results showed that the Root Mean Square (RMS) values of AE signals increased with Q, P and F but decrease with d. Results also showed that the frequency spectrums of AE signals were wideband with multiple peaks at different frequencies. The physical interpretation of frequency spectrum was discussed but was not fully explained.