Abstract
Applicability of acoustic emission (AE) method to the diagnosis of leaks in an engine gasket was studied. Wide band type AE sensors were attached on the gasket around the cylinder, and nitrogen gas was gradually injected to the cylinder in order to occur leaks. It was demonstrated that continuous AE signals due to leaks are detected at the internal pressure exceeding a certain level. Since the average signal level (ASL) was increased according to the internal pressure, it was found that the amounts of leaks could be evaluated by the ASL. It was also found that the AE counts are preferable to detect the occurrence of leaks because of the feature that the leaks lead to significantly change of the counts. The result of wavelet transform of the leak AE signal indicates that both of the peak frequency and its intensity vary with time so that the time-frequency analysis is useful to evaluate the leak behavior.
