Sensor sensitivity studies towards development of impact event detection system for composite laminates and metallic plates\ud \ud

Accidental damages caused by low velocity impact events such as tool drop is a source of concern for designers of composite aircraft structures. Low-velocity impacts can create subsurface damages in a composite structure that can significantly reduce the load-carrying capacity of structure, yet showing barely visible impact damage (BVID). Presently, aerospace structures are designed to be damage tolerant and fail-safe in order to sustain BVID since they are likely to go undetected during periodic manual inspection. A real time impact detection system can result in reduction of direct operating and maintenance cost of the aircraft providing confidence in structural integrity of the structure. This paper describes the studies carried out to understand the sensor behaviour towards the impact event for metal plates and composite laminates. Experimental sensor sensitivity studies carried out for metal plates and composite laminates to determine the sensor response for various radial distance, sensor orientation and impact energy. The paper also presents the development and validation of time-based and strain amplitude based algorithms to identify impact location on a metal plate