Autonomous piezoelectric structural health monitoring system for on-production line use

The aim of this study is to control aeronautical composite structures on production line since they are extremely vulnerable to impact damages due to tool drops for example. To detect such an event on the structure, a piezoelectric wireless sensor network has to be developed. Therefore the feasibility of an innovative technique based on a piezoelectric harvesting device is presented. The system carries out structural health monitoring tasks using piezoelectric transducers bonded onto the structure and is also fully autonomous since the same transducers are used to convert the mechanical vibrations of the structure into electrical power. As vibrations are not available during the production process, the autonomy of the system is provided thanks to a Lamb wave emitter located in the sensor array. After measurements, the system is able to harvest 7·36 milli-watts for a 100 milli-watts mechanical power applied to the structure. This electrical power can be used both by the electronic detector and the WIFI transmitter for the detection of impacts of less than 1 Joule.