Autonomous wireless sensor network for structural health monitoring of aerostructures

In this work we demonstrate the feasibility of an embedded, cheap, miniaturized active sensor node for detection of damages on laminate composite or metallic structures by means of ultrasonic guided waves (GWs). The device is meant as the basic building block of an autonomous wireless sensor network (AWSN) able to monitor the integrity of the aerostructure and locate possible damages. Each node is permanently mounted on the surface and wirelessly powered by electromagnetic (EM) waves, which are also used for communication with the base station. The electronic circuit is interfaced with an innovative, patent-pending piezoelectric transducer (piezo) capable of generating and sensing directional ultrasonic GWs in the inspected structure. Elastic waves propagating through the structure and reflected back to the piezo are recorded and processed by each individual node thanks to embedded processing functionalities to detect and locate defects. The information is then sent back to the base station for further analysis and evaluation. The results highlight that a small, lightweight and low power system can be designed with off-the-shelf hardware. The proposed system provides good reliability and accuracy and brings many advantages over current systems.