The Design And Fabricate Technology Of High Temperature FBG Strain Sensor

Due to their advantages of small size,excellent anti-electromagnetic,high sensitivity and accuracy based on fiber Bragg grating(FBG)are attractive for a wide range of sensing application,such as petrochemical industry,bridge construction,power industry and other fields.In the petrochemical industry,it is necessary to maintain strain monitoring of structures operating in high temperature environments,the resistance strain gauge can not be used in the petrochemical industry because of the safety problem.However,the traditional FBG strain sensor is not enough to meet the measurement requirements in the high temperature harsh environment.Therefore,the application of fiber Bragg grating strain sensor in high temperature is studied in this paper,the main work is as follows:1.A suitable high temperature resistant fiber Bragg grating is selected,it is polyimide-FBG,a double rhombus sensing structure with strain-sensitive effect was designed,the fixing way of the sensor was determined as bonding with high temperature resistant adhesive.Finally,a high-sensitivity fiber Bragg grating strain sensor was developed which can work at high temperature.2.The formula of the sensitization effect of the double rhombus strain sensing structure is deduced,and the relationship between the measured strain and the center wavelength shift of the grating is determined.Finally,the drift of the Bragg wavelength after the pre-drawing is analyzed.3.The stress simulation of the double rhombus sensor structure,the strain concentration type and the square type sensing structure were carried out with ANSYS finite element analysis software.The displacement and stress distribution of the three strain transmission structures under external strain were obtained.4.Finally,the strain characteristics and temperature characteristics of double rhombus structure under high temperature environment were tested.When the compressive strain is increased to a certain value,the curve is flat,because the grating is pre-drawn in advance,after the strain reaches a certain value,thepre-drawing is canceled and the grating is restored.The experimental results show that the sensor can work normally at 300?.The average tensile sensitivity and compressive strain sensitivity of the sensor were 3.049 pm/?? and 3.259 pm/??.