Strong interference denoising method for the multiple damage acoustic emission signals of the aircraft composite structures

Composite materials are necessary for the aircraft structures. During the manufacture, assembly and service process, however, the aircraft composite structures have the multiple damages by impacts, fatigue, or overloading. The type and location of the damage can be identified by structural health monitoring (SHM). When any kind of damage occurs, a different transient non-stationary acoustic emission (AE) signal can be detected. However, these AE signals are very weak, and often affected by fatigue loading and other environmental noise. Therefore, before analyzing the damage, the denoising method is important for the obtained AE signals. This paper proposes a strong interference denoising method based on the reference channel. Firstly, generate the reference channel signal due to the aircraft structural fatigue test loading spectrum. Secondly, the reference channel signal and the sensor monitoring signals act as the observation signals for the blind source separation (BSS). Finally, the wavelet denoising (WD) is executed to the recovery signals after BSS. The simulation results show that in the fatigue loading condition, the BSS based on the reference channel can remove the strong interference signals of the composite structure damage AE signals.