Study On Dynamic Characteristic Of Fiber Bragg Grating Accelerometer

With the development of technology in the aviation engineering, aeronautics engineering, oceanics, petroleum engineering and civil engineering, dynamics problems become more and more complex, more advanced vibration testing and analysis technology have to be provided to assure the project safety and economy rationalization. Electromagnetic accelerometer that is widely used currently has not achieved the requirement. As a brand-new sensing technology, fiber Bragg grating sensing technology has many advantages which traditional sensing technology do not possess. Accordingly, study and development of fiber Brag grating accelerometer is very significant.Fundamental principle and technique that measure acceleration by fiber Bragg grating sensing technology has been studied by the numbers, which establishes theoretical foundation for measuring acceleration by fiber Bragg grating sensing technology and has definite instructional meaning for designing fiber Bragg grating accelerometer.1. Design and optimization method have been provided in this paper. The method of measuring acceleration by fiber Bragg grating has been studied, kinetics model of fiber Bragg grating accelerometer has been established, dynamic response of fiber Bragg grating accelerometer has been analyzed, fundamental dynamic parameter's achieving technique of fiber Bragg grating accelerometer have been offered.2. In this paper, the theoretic structure of fiber Bragg grating accelerometer has been brought forward firstly and analyzed by analytic method and finite element method respectively. The theoretic result of has been testified by experiment, which demonstrate that finite element method applied in design and analysis of fiber Bragg grating accelerometer is valid.3. According to demand of large-scale bridge and civil structure health monitor, a new type of fiber Bragg grating accelerometer which has low nature frequency and high sensitivity has been come forth. Analysis approach of static and dynamic characteristic has been developed by finite element method software, ANSYS. And the analysis subroutine has been programmed using APDL language to optimize and analyze accelerometer. The result of optimization and analysis show: 1) across-axis sensitivity is smaller, less than 2% of the primary axis sensitivity; 2) the first mode is dominant at primary axis, which reduce intersectional coupling; 3) when damp ratio is between 0.3 and 0.7, accelerometer has better dynamic characteristic.