A major issue facing the world’s inventory of aging steel bridges is cracking associated with fatigue damage. The primary method used to evaluate these cracks is visual inspection. However, visual inspection is labor intensive, misidentifies cracks and may have insufficient inspection intervals. To provide a more reliable way to monitor fatigue, a Fatigue Fuse (FF) system is proposed that integrates a piezoelectric status monitor, an energy harvester, and a wireless communication link. The FF is a highly calibrated metal analog sensor made of the same material as the host structure. It is designed with several pre-notched ligaments that fracture after specific number of load cycles have been accumulated. The steel FFs are undergoing qualification to bring them to a technology readiness level of 6. Currently, the fuses require visual inspection, but it can also be self-powered and interrogated remotely by incorporating a piezoelectric pitch-catch circuits and kinetic energy harvesting system. The pitch piezoelectric excites a fundamental acoustic mode in the FF and the catch piezoelectric senses the vibration. When the crack propagates across the fuse, the resulting catch electrical signal changes along with the mechanical stiffness of the fuse. This mechanical information is stored in the fuse and the fatigue status then needs to be interrogated and sent across a wireless network. As a result, the electronics for remote sensing can remain in a low power dormant mode. This fatigue monitoring system provides a convenient method to assess the useful life of steel infrastructure and prevent catastrophic failures.
DOI: https://doi.org/10.32548/RS.2018.031
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