| Structural strain is a key parameter that reflects the mechanical characteristics of rotating structures,which can provide an important basis for fault diagnosis and health management of the whole machine.The optical fiber Fabry-Perot sensor has the advantages of small size,strong anti-electromagnetic interference and stable performance.Fabry-Perot sensor is widely used in harsh environments such as high temperature and high pressure.The thesis is of important scientific significance and practical value for the research of optical fiber Fabry-Perot strain sensing measurement technology for rotating structure.In this thesis,based on the demand of the optical fiber strain sensing system of the rotating structure,the overall scheme of the measurement system is designed.The theories of influencing factors are analyzed.And the measurement system was designed.The relevant experiments were carried out.Detailed contents are given as follows:(1)A strain measurement scheme based on fiber optic Fabry-Perot strain sensing is conducted.Non-contact collimators transmission and glass wafer oblique incidence demodulation is proposed.The main factors affecting the quality of demodulated signals are analyzed.There is influence on the intensity of the demodulated signal caused by axial float,radial translation and angle of the rotating structure.At the same time,the influence of the parameters of the glass wafer and its installation on demodulation precision and range are analyzed,including the thickness unevenness of the glass wafer,surface reflectivity,refractive index,and the installation angle of the fiber end.The reasonable design of the above parameters is helpful to meet the measure requirements.(2)The hardware design is completed,including fabrication of coated Fabry-Perot sensors,the design and detection of glass wafer,the design of cylindrical mirrors,the circuit code of MSP430F6638 system,the light energy analysis,and the driving code of CCD;The software based on labview is completed.(3)An optical fiber Fabry-Perot strain sensing system with a rotating structure is built;the static strain measurement experiment of the rotating structure was carried out.The experiment data shows that the cavity length of the Fabry-Perot sensor obtained by demodulation has a good linear relationship with the applied load.The strain sensitivity is 0.01341μm/με ～ 0.01392μm/με.The dynamic strain measurement experiment of the rotating structure is carried out,and the Fabry-Perot cavity length curve within the rotational speed of 10 r/min is obtained.The results show that the measurement of the rotating structure strain can be conducted by the sensing system based on collimators coupling and glass wafer demodulation.The dynamic experiment results are affected by centrifugal force,wind force and shaking during rotating,and the error of the measurement results is larger than that of the static experiment.The mean sum of squares of residuals(RSS)of static experiment results was 42.75% of that of dynamic experiment results. |
