Local area damage detection in composite structures using piezoelectric transducers

An integrated and automated smart structures approach for structural health monitoring applications is presented. This approach, called Active Damage Interrogation (ADI), utilizes an array of piezoelectric transducers attached to or embedded within the structure for both actuation and sensing. The ADI system actively interrogates the structure via broadband excitation of multiple actuators across a desired frequency range. The structure's vibration signature is then characterized by computing the transfer functions between each actuator/sensor pair, and compared to the baseline signature. Statistical analysis of the transfer function deviations from the baseline is used to detect, localize, and assess the severity of damage in the structure. Experimental results of applying the ADI system for local area damage detection in a MD Explorer rotorcraft composite flexbeam are presented. The performance of the system in detecting and localizing internal delaminations created by low velocity impacts is quantified. The results obtained thus far indicate considerable promise for integrated structural health monitoring of aerospace vehicles, leading to the practice of condition-based maintenance and consequent reduction in vehicle life cycle costs.