Monitoring of the acoustic emission (AE) from the progressive fatigue damage is categorized as the passive online monitoring. SHM has been introduced for both active and passive damage identification for the real-time monitoring of the structures. The structural health monitoring (SHM) technology is increasingly used for the detection of progressive defects in the critical aerospace structures. It has been shown that some high-frequency contents of the AE signal have developed as they travel away from the crack. The distance effect on the captured AE signals was also studied. The low-amplitude fatigue-crack related AE signals were successfully captured by the PWAS transducers. The fatigue crack was generated in the test coupon which had produced low-amplitude acoustic waves.
Two PWAS transducers were bonded to the thin aerospace test coupon. To validate the multiphysics simulation results, an in-situ AE-fatigue experiment was performed. The simulation results showed that both PWAS transducers were capable of sensing the AE signals. The simulated AE event was generated at the crack tip. One PWAS was placed near to the fatigue-crack and the other one was placed at a certain distance from the crack. Various configurations of the sensors were studied by using the simulations. Multiphysics finite element (FE) simulations were performed with two PWAS transducers bonded to the structure. In this article, we have shown a new avenue of using the PWAS transducer for detecting the low-amplitude fatigue-crack related acoustic emission (AE) signals.
However, in most applications of active sensing, the signals are of high-amplitude and easy to detect. Piezoelectric wafer active sensors (PWAS) are commonly used for detecting Lamb waves for structural health monitoring application.
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