Overview
An evaluation of Structural Health Monitoring (SHM) concepts shall be performed. This includes a discussion of concepts, state-of-the-technique (approved, implemented, certified by, etc.), manufacturers, practical examples of integration on flying systems. The discussion shall address advantages and limitations, detectability, degradation mechanisms, durability of the sensors, space required for installation, etc. The focus of this study lies on retrofitted systems for direct damage detection on metallic local area (hot spot) and possibly into composite (area monitoring) for non-continuous, off-board resp. on-ground damage monitoring.
In addition, a specific assessment of the Comparative Vacuum Monitoring (CVM) technology shall be performed in the lab on structrual design feature of a fighter aircraft, which require NDI monitoring as part of the scheduled maintenace plan. The CVM principle relies on placing a sensor onto the surface where damage is expected to occur. The sensor contains fine channels in parallel which are open to the surface. Once the sensor has been installed on the surface, the channels form closed “galleries” to which a vacuum can be applied. The sensor is connected to a vacuum source with an accurate flow- and pressure meter . If a crack develops, a leakage path will form and the vacuum level will be reduced in the sensor manifold. Probability of Detection (POD) curve shall be derived based on the one-sided tolerance interval (OSTI) method.
