Packaging Structure Design And Experimental Verification Of High Temperature Fiber Grating Sensor

At present,with the rapid development of various kinds of aircraft,the temperature of the service environment is also increasing,and the heat protection problem caused by the harsh aero thermal environment has become a problem for the development of all kinds of high-speed aircraft.At present,the sensing technology in the high temperature field can not obtain the thermal response of the material under the high temperature environment,which has brought great difficulties for the thermal design and analysis.Fiber Bragg grating sensor can measure the temperature and strain at the same time.It has the characteristics of high resistance to electromagnetic interference,high temperature resistance and small size.It has its unique advantages.In this paper,the high temperature connection scheme and packaging structure of quartz fiber grating sensor are designed and tested.The sensing mechanism of fiber Bragg grating under different connection schemes is analyzed from the strain transfer mechanism of the integrated bonding and holding sensor,and a new type of bonding scheme is proposed: two-point bonding scheme.Based on the method of separating the solidified colloid,the design plan for the die is carried out.Through the establishment of the pre-tightening force system,the experiment on the pre-tightening force of fiber Bragg grating is carried out.It is proved that this method can effectively solve the problem of the non-strain response of the fiber Bragg grating at the initial stage of heating.The thermal structure response test system of optical fiber sensor is designed and established,and the thermal structure response test is carried out on two typical heat proof materials.The results show that the precision of the two-point connection scheme is superior to the precision of the integral connection scheme,and the rationality of the new scheme is verified.Based on the basic idea of protecting fiber Bragg grating sensor,the packaging structure design and experimental verification of fiber Bragg grating sensor are carried out of two-point bonding scheme.Considering the long curing cycle of the high temperature adhesive,the electric heating wire groove is designed in the package structure,which can greatly reduce the curing time of the high temperature glue.For the design of the paraffin mold,the encapsulation experiment of the optical fiber sensor was carried out.The quantitative coating of colloid and the nondestructive stripping of the solidified colloid were realized,and the solidified colloid and the package die were separated successfully.The high temperature thermo strain test was carried out for two specimens of UHTC and high temperature alloy.The strain data of the optical fiber sensor was obtained.The average error of the package structure between 200-600 degrees centigrade was less than 7%.