Research On Fiber Bragg Grating Acoustic Emission Sensor

With the integration of modern large-scale mechanical structure and industrial equipment,acoustic emission detection technology has been developed rapidly and applied widely.The traditional acoustic emission detection system uses the resonant high sensitivity sensor,this type sensor has a series of disadvantages including narrow working band,weak electromagnetic interference ability and high requirements for the use of the environment,which restrict the further development of acoustic emission detection technology.Therefore,fiber Bragg grating sensor with light weight,small volume,strong electromagnetic interference resistance and strong environmental adaptability has become the focus of research.In this paper,the fiber Bragg grating acoustic emission sensor packaging is designed through simulation experiments,and the fiber Bragg grating acoustic emission acquisition system is compiled.According to the laws of the fiber Bragg grating strain transfer,the factors influencing the sensor sensing ability are analyzed,combined with optical fiber Bragg grating and the mechanism of the acoustic emission waves,this paper studies packaging materials and packaging size of sensor.The temperature characteristics of the encapsulated materials are simulated by COMSOL,the results show that the lower the temperature coefficient of the encapsulated materials in a certain range,the less the influence of temperature on the accuracy of the detection system.The packaging materials of sensors are simulated by COMSOL,the results show that the reduction of acoustic emission wave caused by the encapsulation of sensors made of acrylic glass is significantly smaller than that of stainless steel.Through the size simulation analysis of the length and width of the package by COMSOL,the effect of height and length on acoustic emission waves is consistent in the case of changing only one parameter.The greater the parameters,the stronger the attenuation of acoustic emission waves;And the change of the package width almost does not affect the acoustic emission wave.According to the overall analysis,under the condition that the sensor can be completely contacted,the smaller the size of the Fiber Bragg grating acoustic emission sensor package,the higher the detection sensitivity.By analyzing the principle of the narrow band laser demodulation method of the fiber grating acoustic emission sensing system,the hardware experiment platform is built by using the LabVIEW programming software,and this paper designs the optical fiber grating acoustic emission acquisition system and establishes the hardware experimental platform.Using the fiber grating acoustic emission sensing system,the test of steel plate lead breaking and the failure experiment of rotating mechanical bearing are carried out.The experimental results show that the fiber Bragg grating acoustic emission sensor can be sensitive to the signal of lead break and the signal of the fault bearing signal.