Active self-sensing scheme development for structural health monitoring

Abstract

Smart materials such as lead zirconate titanate (PZT) have been widely used forgenerating and measuring guided waves in solid media. The guided waves are thenused to detect local defects for structural health monitoring (SHM) applications.In this study, a self-sensing system, composed of self-sensing algorithms and aself-sensing circuit equivalent to a charge amplifier, is developed so that a single PZTwafer can be used for simultaneous actuation and sensing. First, a PZT waferis modeled as a single capacitor and a voltage source, and a so-called scalingfactor, defined as the ratio of the PZT capacitance to the capacitance of thefeedback capacitor in the self-sensing circuit, is estimated by applying knownwaveforms to the PZT wafer. Then, the mechanical response of the PZT wafercoupled with the host structure’s response is extracted from the measured PZToutput voltage when an arbitrary excitation is applied to the same PZT wafer.While existing self-sensing techniques focus on vibration controls, the proposedself-sensing scheme attempts to improve the accuracy of extracted sensing signals inthe time domain. The simplicity, adaptability and autonomous nature of theproposed self-sensing scheme make it attractive for continuous monitoring ofstructures in the field. The effectiveness of the proposed self-sensing scheme isinvestigated through numerical simulations and experiments on a cantilever beam.