應用干涉型光纖感測器量測懸臂樑結構振動

The Measurement of A Vibrating Cantilever Beam with Interferometric Fiber-Optic Sensor

楊智閔(Chih-Min Yang)

指導教授 ： 何旭川

元智大學/工程學院/機械工程學系/碩士(2007年)

https://doi.org/10.6838/YZU.2007.00260

摘要

光纖在通訊之應用早為人所熟知，近幾年更被廣泛應用於量測，光纖體積小，韌性高，抗腐蝕以及抗電磁干擾的特性，非常適合作為感測器量測結構之微小變化。本文主要探討光纖感測器在結構振動之量測應用，結合光彈理論與Mach-Zehnder干涉推導出光相位差與應變關係，應用3x3光耦合器三個輸出端具120 相位差之特性，以數學運算解調Mach-Zehnder兩干涉光路之相位差，再由光相位差求得結構應變。並以懸臂樑為例說明Mach-Zehnder干涉型光纖感測器之量測方法，包含基座激振、強制振動及自由振動三種不同振動模式，頻率的選擇則涵蓋單一頻率、雙頻率、共振與非共振之多種不同組合，並將光纖感測所得振動應變與應變規量測值比較，以驗證量測準確性。

關鍵字

光纖感測器,Mach-Zehnder干涉儀,3x3光耦合器,懸臂樑,強制振動,基座激振,自由振動

並列摘要

Optical fibers are well known in the applications of communication. Optical fibers possess the advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, the Mach-Zehnder interferometric fiber-optic sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3x3 coupler is utilized to demodulate the phase shift of the Mach-Zehnder interferometry. The dynamic strains of the cantilever beam subjected to free vibration, base excitation and forced vibration are determined by the optic-fiber sensor, The selected frequencies for the vibration test include resonance, non-resonance, single frequency and double frequencies. The experimental results are validated with the strain gauge.

並列關鍵字

fiber optic sensors, Mach-Zehnder interferometry, 3x3coupler, cantilever beam, vibration

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