DEVELOPMENT OF AE ARRIVAL TIMES DETECTION METHOD BY USE OF ROOT MEAN SQUARE VOLTAGE IN NOISE

Abstract

In order to evaluate the failures inside the materials, Acoustic Emission (AE) techniques, which is attractive in the failed of the structural health monitoring and model tests, have been applied to the non-destructive tests (NDT), and it has been used to identify the elastic wave velocity distributions and the failures in recent. AE is emitted at the occurrence of the cracks and/or the frictions, and the elastic wave frequencies and velocity are related on the targets situation. Therefore, AE behaviors are potential to visualize the failures on real time if AE measurements are constantly conducted. However, NDT which based on AE techniques, requires the accurate arrival times of AE to clearly visualize the inside of the materials. To visualize it practically, the arrival times should be detected automatically since the amount of the AE measurement data is generally huge. In this paper, a method of AE arrival time detection is proposed based on the root mean square voltage in the noises. The proposed method is verified on the model tests in which pencil lead breaks conduct on the aluminum plates to detect the AE arrival times, and the accuracy of the arrival times investigated on the proposed method and the conventional method. The result of the investigation show that the proposed method detects more accurate arrival time in the low S/N signal, in comparison with the conventional method. The suggests that the proposed method improves the results of NDT which based on the arrival times of AE.