| Summary: | 碩士 === 國立中正大學 === 光機電整合工程研究所 === 99 === The conventional strain gauges has higher sensitivity of a gauge factor about 120 for semiconductor strain gauges and a gauge factor about 2 for foil strain gauges. But both are wired gauges and can not be applied on the rotating shaft. In order to overcome the drawbacks of the conventional strain gauge, the magnetoelastic thin film is used as the sensing medium of higher sensitivity, and a solenoid wireless sensing is developed. This paper is based on the magnetoelastic effect to fabricate a wireless magnetoelastic strain sensor, where a Metglas 2826MB (Fe40Ni38Mo4B18) amorphous ribbon is used for their low cost and high sensitivity. The ribbon was attached to a FR4 slab. As the stress was applied on FR4 slab, the magnetic field changed due to the mechanical deformation of magnetoelastic thin films, and further induced the change in the magnetic flux, which was then detected by a wireless sensor of detection coil.
In this paper, the solenoid is place as a component in a RLC oscillation circuit and is use to detect the magnetoelastic thin film. Another method is the concentric induction coil setup, in which the stimulus are injected into the magnetoelastic thin film by using an excitation coil and then a pick-up coil is used to detect the response signal. As the stress was applied on magnetoelastic thin films for the RLC oscillation circuit with a frequency at 55KHz, was found gauge factor equal to 160. For the concentric induction coil setup with a frequency at 1.7MHz, was found gauge factor equal to 851.
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