Development of Vibration Sensor Using Giant Magnetostrictive Material for Self-Powered Structural Health Monitoring System

A novel vibration-sensing device based on the giant magnetostrictive effect for a self-powered structural health monitoring system was developed. This device can produce a large voltage because the magnetostrictive rod, in principle, can generate a large variation in magnetic flux density, even when it is subjected to small and low-frequency vibrations of the bridge girder. Therefore, the device could function as a power generator to supply power to a storage battery, when it is not being used as a vibration sensor, to drive the electric circuit. A field test for the developed device was conducted. The experimental results confirmed that the device worked as a vibration sensor with considerable accuracy in detecting the natural frequency of the bridge, even when subjected to the intermittent load of passing cars.