A wideband damage source localization method using enhanced virtual time reversal mirror technique and modal analysis with sparse acoustic emission array

In order to reduce the possibility of damage or leakages in the pressure vessels, acoustic emission (AE) array is typically utilized in the structural health monitoring (SHM) and integrity assessment in view of its high sensitivity. However, accurately analyzing and localizing a wideband AE source in practice can be challenging due to the complex dispersion and multi-mode behavior of AE signals. In this study, an enhanced virtual time reversal mirror (VTRM) imaging method was proposed aiming to solve this situation. This method was comprised of Morlet wavelet transform, time reversal mirror technique and a multi-window energy ratio indicator, which can be used to reconstruct ultrasonic images and reveal the damage locations. The proposed method was testified on a steel plate, using standard Hsu-Nielsen source localization experiments with many different source locations and array layout configurations, hence guaranteeing its reliability and repeatability. In contrast with time difference of arrival and single-sensor model acoustic emission methods, it was validated to eliminate the noise disturbances and echo interferences, significantly reducing the risk of artifacts and obtaining a much higher stability and noise resistance than the compared methods. In conclusion, the feasibility of the proposed method in complex AE source localization has been sufficiently confirmed, and it has the potential to be further studied in more practical SHM applications in the future.