Abstract
Acoustic emission (AE) technique is widely used for health monitoring of machines. However, it is difficult to monitor structural components that has rough surface or that is under operating. In order to monitor these components, non-contact AE monitoring system with noise reduction function was developed. The developed system was composed of an air-coupled ultrasonic transducer and a digitizer with a real-time noise reduction function. Two types of digital signal processing for improving signal to noise ratio were embedded in the system. One is a spectral subtraction process for reduction of continuous noise. The other is E-filter process which filters out pulse-like noise. Artificial AE signals were monitored to compare the performances between conventional AE system and developed one. The S/N ratio of the AE signal was improved by 12.3 dB by the developed system.
