Fatigue crack length measurement of sputtered metal film for rfid-based smart stress memory patch

Abstract

A new sensor, which can estimate fatigue damage parameters such as number of cycles and stress amplitude, was proposed and fabricated based on smart stress memory patch. This sensor composed of an ion-sputtered metal film deposited on the smart stress memory patch (a thin copper specimen). The crack extension of the sensor during fatigue test could be estimated by measuring the electrical resistance change of the ion-sputtered metal film. The relationship between normalized electrical resistance and the crack extension obtained from the experiment showed a good agreement with that predicted by FEM analysis. This new sensor was combined with two wireless systems using commercially available wireless module and RFID tag. The capability of these systems was evaluated and the results showed that both systems were successfully applied to measure the crack length of the smart stress memory patch. It demonstrated that the proposed systems have potential as a wireless sensor for structural health monitoring, which enable long-term fatigue evaluation with features of easy configuration, wireless and powerless. © 2011 ISIJ.