A unified approach for the structural health monitoring of waveguides

Abstract

In this article, the simultaneous use of ultrasonic testing and impedance-based technique to monitor the health of structural waveguides is proposed. Methods based on the propagation of guided waves are increasingly used in all those structural health monitoring applications that benefit from built-in transduction, moderately large inspection ranges, and high sensitivity to small flaws. In the meantime, impedance-based method promises to adequately assess the structural integrity of simple and complex structures that include welds and bolts. As both wave-based and impedance-based approaches can utilize piezoelectric transducers (lead zirconate titanate) bonded or embedded to the structure being monitored, this article describes a unified structural health monitoring paradigm where these techniques are employed simultaneously, driven by the same sensing/hardware/software unit. Specifically, we propose to use two lead zirconate titanates controlled by a National Instruments–PXI running in LabVIEW. An ad hoc LabVIEW Virtual Instrument controls signal output and input as well as processing and storage. To assess the feasibility of this unified system, an aluminum plate and a steel pipe were monitored. Damage was simulated by changing the boundary conditions of each structure. The results show that the proposed system is robust and can be developed further to address the challenges associated with the structural health monitoring of complex structures.