Wireless Fiber Optic Acoustic Sensors for Crack Monitoring

摘要

Fiber optic sensors have many advantages:electromagnetic immunity,chemical inert property,compactness,flexibility etc.Large structures are necessary to use huge number of sensors to get the information about the external condition and the internal structural condition.Such huge number of sensors should be connected by cables between sensor conditioners and sensor probes.This instrumentation is very huge laborconsumable process.In this paper,fiber optic acoustic sensor modules were developed with a probe unit,a sensor control unit,and a wireless unit to detect the change of some acoustic signals from crack growth of structures.The probe unit was constructed with an optical fiber Bragg grating.The sensor control unit had some feed back circuit to control wavelength of the light source.Also,the wireless unit was combined with the probe unit and sensor control unit to communicate the host computer.Crack monitoring experiments were simulated by an impact test of an aluminum plate.The sensor could make some crack growth detection event data and transmit the data to the host computer.The change of crack growth was well detected by the sensor probes,and transmitted by wireless unit to the host computer.