For the first time ever, a team of researchers successfully developed and tested networked acoustic emission sensors that can detect airframe damage on conceptual composite UH-60 Black Hawk rotorcraft.
Researchers with the U.S. Army Research Laboratory and the U.S Army Aviation and Missile Research, Development and Engineering Center said their discovery opens up possibilities for new onboard features that could immediately alert the flight crew to the state of structural damage like matrix cracking and delamination as they occur, giving the crew greater opportunity to take corrective actions before catastrophic failure.
Acoustic emission sensing is a passive non-destructive technique for detection of damage in the very early stage, and long before the structure experiences catastrophic failure. Unlike other methods, Acoustic emission detects damage in real-time (or at the instant the damage is happening). The fact that AE is passive means that it does not require an external energy to detect damage. It relies on the energy that is initiated within the structure, Haile explained.
"The novelty of the current work is that we introduced several new concepts on wave acquisition control and signal processing to recover damage related information in networked acoustic emission sensors," Haile said. "The Eureka moment was when the sensing network consistently identified and located the initiation and progression of damage during a prolonged fatigue test that lasted over 200,000 cycles -- a feat that has never been achieved before."