光纖光柵量測結構振動與衝擊響應

The Measurement of Structural Vibration and Impact Response by Fiber Bragg Grating Sensor

鍾士傑(Shin-Chieh Chung)

指導教授 ： 何旭川

元智大學/工程學院/機械工程學系/碩士(2008年)

https://doi.org/10.6838/YZU.2008.00292

摘要

光纖光柵傳感器具有抗電磁干擾、尺寸小、重量輕、低損耗、傳輸距離遠、易形變等優點，已被廣泛使用於通訊和感測技術。本文以短週期光纖光柵結合長週期光纖光柵組成感測系統，量測結構承受振動與衝擊之應變響應，量測方法是利用短週期光纖光柵受到形變時會反射不同的波長，短週期光柵的反射波透過光路系統進入長週期光柵，因為長週期光柵在不同的光波段有不同的衰減量，可藉由量測光強度之變化求得短週期光柵反射波長之變化，進而計算結構承受振動與衝擊之應變響應。本文將此光纖光柵量測方法，應用於樑與電路板之結構振動與衝擊實驗，其中振動實驗包含自由振動、基座激振、強制振動，衝擊實驗包含敲擊與掉落實驗，邊界條件則包含單邊固定與雙邊固定。再將所有光纖感測系統輸出之光強度訊號透過關係式轉換成應變訊號並與應變規訊號作比較，驗證此光纖感測系統量測結構振動與衝擊的可行性。

關鍵字

長週期光柵 ； 短週期光柵 ； 自由振動 ； 強制振動 ； 基座激振 ； 衝擊響應

並列摘要

Fiber-optic sensors with small size, light weight, low attenuation and immunity to the electro-magnetic have the advantages over the conventional sensor. In this investigation, the fiber bragg grating is incorporated with the long period fiber grating to measure the strain of structures excited by a shaker and impact hammer. As the light transmits through the long period fiber grating, the intensity of the light is modulated by the wavelength reflected from the FBG. By measuring the intensity of the light, the wavelength reflected from the fiber bragg grating sensor can be determined, thus, leads to the determination of the strain in the structures. In this investigation, the fiber bragg grating sensor is attached to the beam and printed circuit board. The experimental tests presented in this research including three vibration tests (free vibration, forcing vibration, base excitation) and two transient tests (drop test and impact hammer). The structural strain measured by the Fiber Bragg Grating sensor is compared with the strain gauge. Good agreement between the two sensor demonstrates the capability of FBG sensor in measuring the dynamic and transient responses of the structures.

並列關鍵字

long period fiber grating ； fiber bragg grating sensor ； free vibration forcing vibration ； base excitation ； impact response

參考文獻

18. 周志成，”應用光纖光柵感測器量測結構應變、溫度及振動”， 元智大學機械工程研究所碩士論文 (2006)

19. 謝文斌，”結合光纖光柵與Mach-Zehnder光干涉量測結構振動”， 元智 大學機械工程研究所碩士論文 (2007)

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