Vibration-based SHM with up-scalable and low-cost Sensor Networks

Structural health monitoring (SHM) is becoming increasingly attractive for its potentialities in many application contexts, such as civil and aeronautical engineering. In these scenarios, modern SHM systems are typically constituted by a multitude of sensor nodes. Such devices should be based on low-cost and low-power solutions both to ease the deployment of progressively denser sensor networks and to be compatible with a permanent installation; this allows real-time monitoring while reducing the global maintenance costs. Among the developed inspection methodologies, operational modal analysis (OMA) is an efficient tool to assess the integrity of vibrating structures. This article describes a sensor network that is based on either microelectromechanical systems (MEMS) accelerometers or cost-effective piezoelectric devices to extract strictly synchronized modal parameters. The performances of the two sensing technologies are evaluated in two different setups, to assess the reliability in the estimation of modal features even in the presence of potential damages. Particular attention was given to the mode shape reconstruction issue from piezoelectric signals, primarily encompassing a purposely developed modal coordinate tuning procedure. Moreover, the consistency of the obtained results paves the way to a more compact and affordable monitoring system exploiting piezoelectric-driven modal analysis.