Design Of Optic Fiber FP Sensor With High Temperature And Large Strain And Its Application In High Temperature Creep

The single crystal nicked-based superalloy is widely used in aerospace,energy,petrochemical and other fields because of its excellent characteristics such as high temperature strength,excellent high temperature structural stability,outstanding creep and fatigue resistance.However,long-term work in the harsh environment with high temperature and composite load will lead to material creep,resulting in cracks and even complete fracture failure.Therefore,strain measurement for high temperature creep is very important and urgent.In this paper,a new type of optic fiber Fabry-Perot(FP)sensor with high temperature resistance and large strain is designed and applied to the creep measurement of single crystal nickel-based superalloy at high temperature.The main research work of this paper is as follows:(1)Design and performance test of optic fiber FP sensor with high temperature resistance and large strain: The structure design,material selection and preparation process of a new type of optic fiber FP optic sensor are introduced in detail.An experimental test platform is built to carry out the experiments of static strain measurement and temperature response,and the relevant performance of the sensor are tested.(2)Research and analysis of the static tensile experiment of low carbon steel: The optic fiber FP sensor is applied to the static tensile test of 45# to verify the reliability of strain measurement at room temperature and high temperature.In the room temperature experiments,the accuracy and consistency of sensor are tested,and the effect of the tensile rate to mechanical properties of 45# are studied.In the high temperature experiments,the pasting process of fiber sensor and experimental sample are designed and tested.The experimental results of optic fiber FP sensor are compared with electronic extensometer and simulation results of ABAQUS,and the effect of temperature to mechanical properties of 45# are researched.(3)Research and analysis of the high temperature creep experiment of single crystal nicked-based superalloy: The optic fiber FP sensor is used to the high temperature creep test of single crystal nicked-based superalloy,and the creep curve of stress in 300 MPa,320MPa,350 MPa and 400 MPa respectively are obtained at 950?.The steady-state creep stage of creep curve is analyzed,and obtained the relationship between steady-state creep rate and stress and creep fracture time.