Application Investigation Of Fiber Optic Fabry-perot Strain Gage On Wind Tunnel Balance

Fiber optic strain gauge possesses electromagnetic interference resistance, high temperature resistance, simple structure, small size and high sensitivity, which provide a new technical method for the research of wind tunnel strain balance. Nowadays, there are lots of domestic and foreign institutions launching into the research of fiber optic balance, however, majority of them just work on the principle verification of fiber optic balance. In 2010, China Aerodynamics Research and Development Center(CARDC) cooperated with University of Electronic Science and Technology of China(UESTC) on the research which applied fiber optic Fabry-Perot(F-P) strain gauge to wind tunnel balance. But the creep and static accuracy of the fiber optic balance were not good enough that the balance couldn’t be used in wind tunnel experiment.In order to further improve the performance of fiber optic balance and to meet the requirements of wind tunnel experiment, the thesis launches a research on fiber optic balance based on fiber optic F-P strain gauge. This thesis consists of five chapters, each part outlines as followings:In the introduction chapter, the development of wind tunnel balance and the research condition of fiber optic F-P strain gauge and fiber optic balance are introduced in order. Then, research contents of this thesis and scheming indexes of fiber optic F-P strain gauge and fiber optic balance are presented.In the second chapter, the principle of fiber optic F-P strain gauge is first introduced, and then, two fiber optic strain gauge structures are put forward, that’s the strain gauge based on MEMS(Mirco Electro-Mechanical System) chip and laser machining. Next, the structural characteristics, machining process and signal demodulation method of two strain gauges are presented in order. Then, installation process of the strain gauge is launched on constant strength beam, and static tests of the gluing and welding strain gauges are carrried out. Static tests show that the strain measurement accuracy of two fiber optic strain gauges is better than scheming index(0.2με), and the performance of the welding strain gauge is superior than gluing strain gauge.In the third chapter, the three-component balance is designed to further test the performance of fiber optic F-P strain gauge. Static calibrations of fiber optic balances are carried out, and the results are contrasted with resistance strain balance. The tests show that the static preformances(hysteresis, zero drift, creep) and accuracy of fiber optic balance are both better than scheming indexes(0.5% and 1%), but there is still a gap compared to resistance strain balance. Then, temperature compensation techniques of fiber optic balance are preliminary studied, temperature measurement compensation, symmetrical compensation and self-compensating schemes are proposed.In the fourth chapter, wind tunnel experimemts of fiber optic balance and resistance strain balance are carried out in low density wind tunnel. The experiment results show the two balances share the same trend that aerodynamic coefficients vary with angle of attack. The aerodynamic measurement accuracy of fiber optic balance is better than scheming indexes(2%). However, the aerodynamic measurement accuracy of fiber optic balance is still not good enough as resistance strain balance.The last chapter is mainly the conclusions of this thesis, and the direction about the future research are presented.