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Study Of Vibration Sensing Technology Based On Fiber Bragg Grating

Posted on:2008-07-09Degree:MasterType:Thesis
Country:ChinaCandidate:Q N LiFull Text:PDF
GTID:2178360212479545Subject:Measuring and Testing Technology and Instruments
Abstract/Summary:PDF Full Text Request
More and more vibration sensing and measuring problems should be solved urgently in the fields of aviation, spaceflight, petroleum, ocean, bridge, etc., so as to assure the safety of the large engineering structures. Nevertheless the currently used electromagnetic accelerometer is difficult to meet the measuring requirements. Fiber Bragg grating (FBG) sensor is one of the fiber-optic sensors which has been developed rapidly in recent years. It has many advantages such as anti-interference in electromagnetism, high-sensitivity, light weight and compaction in construction, so the investigation of a FBG vibration sensing technology with first priority to acceleration is of great significance.A method of FBG vibration sensing and measuring technology based on equal-intensity beam was proposed, and the scheme was analyzed theoretically and investigated experimentally in this thesis. The main contents are included as follows:Firstly, the characteristics of the common vibration sensor and fiber-optic sensor, and the research and development status of FBG vibration sensors were briefly introduced. Secondly, the FBG fabricating method, sensing principle and common wavelength demodulation technique were summarized. And the advantages and disadvantages of all kinds of demodulation techniques were analyzed in detail.Thirdly, two FBG vibration sensing schemes based on the convexity cross-section beam and equal-intensity beam were designed, and the strain sensing principles using the two different beams were analyzed, respectively. The optimized results and the mode analysis of convexity cross-section beam were carried out using the software of ANSYS. By analyzing and comparing the advantages and disadvantages of the two methods, the equal-intensity beam was finally chosen in the FBG vibration sensing scheme.Lastly, the FBG strain and vibration sensing characteristics were investigated experimentally, and the experimental results were analyzed. In the strain sensing experiments,three FBGs with different parameters were pasted in turn at different positions of the beam, and the strain sensing and measuring experiments were accomplished. After that, the two FBGs were pasted on the top and bottom surfaces to compensate the influence of temperature change on the strain sensing and measuring experiments. On the basis of the experiments, the vibration sensing experiment was carried out using single FBG and two FBGs, respectively. The experimental results had shown that when the single FBG was used, the vibration system could obtain a sensitivity of 0.098pm/g, a natural frequency of 113.2Hz, and an acceleration range of 10.193g~244.623g; when two FBGs were employed, the FBG measuring system could compensate temperature effect, and it achieved sensitivity of 0.196pm/g, and an acceleration range of 5.096g~254.816g.
Keywords/Search Tags:fiber Bragg grating, vibration sensor, cantilever beam, acceleration
PDF Full Text Request
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