Localizing acoustic emission sources in composite plates with unknown wave velocities

Due to the anisotropic nature of composite materials, most traditional triangulation techniques fail to accurately localize acoustic emission (AE) sources in composite laminates. This paper proposes a reliable method to localize acoustic emission sources in composite plates without knowing their wave velocities. Three closely spaced passive PZT sensors were employed to collect acoustic emission signals. The method localized the acoustic emission source in two steps. First, a cross-correlation analysis was applied to the received S0 waves to obtain their time difference of arrivals (TDOAs), thus the direction of the source with respect to the sensor group could be determined considering geometric relations. Then, a continuous wavelet transform was employed to identify the time of arrivals (TOAs) of received A0 waves. With the TOAs of both S0 and A0 waves, the distance from the source to the sensor group was obtained. A finite element analysis with ABAQUS was conducted to validate the proposed method.