The objectives of this project pertain to the development and experimental assessment of a unified probabilistic structural health monitoring (SHM) and aeroelastic awareness approach for VTOL aircraft operating under varying conditions and uncertainty. Current state-of-the-art SHM methods offer significant advantages compared to traditional nondestructive evaluation (NDE) techniques, such as no requirement for visual inspection, significantly reduced cost, and potential for in-situ automated operation. However, when it comes to VTOL aircraft structural components, such as rotorcraft blades and airframes, under varying operating (rotorcraft velocity, rotor RPM, varying centrifugal force, blade configuration and morphing, changes in blade root boundary conditions, etc.) and environmental (altitude, temperature, humidity, gusts, etc.) conditions, existing methods face significant challenges due to (i) the dynamic and stochastic time-variant and potentially non-linear structural response, and (ii) the incipient damage types and complex failure modes of composites that can be easily masked by the effects of varying states and environments. Therefore, the goals of this project are: I. Development of a “local” statistical SHM approach based on active sensing acousto-ultrasonic methods that can operate within varying conditions/environments and can provide appropriate diagnostic statistical detection, localization and quantification confidence intervals; II. Development of a “global” statistical approach based on the principles of passive sensing vibration-based SHM. The term “global” refers to damage modes that affect the global dynamic response of the structural components and can have a significant impact on the operational capability of the VTOL aircraft and as a result to its safety; and III. Development of a probabilistic framework for the integration of the “local” and “global” methods in order to enable the unified treatment of the VTOL aircraft SHM and pave the roadmap to aeroelastic/structural awareness, condition-based maintenance and complete safety assurance.
