光纖光柵在單搭接膠合接口完整性監測之應用

Monitoring Single Lap Joint Integrity with Optical Fiber Grating

楊易叡(Yi-Jui Yang)

指導教授 ： 單秋成

國立臺灣大學/工學院/機械工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201601666

摘要

近年來，黏膠性能的提升，使得膠合接合的應用日趨普遍，但關於膠合接口完整性監測的研究，尚缺乏全面性的探討。因此本研究採用布拉格光纖光柵 (fiber Bragg grating, FBG) 感測器，利用其可內埋於結構內的優勢來偵測膠合接口內因破壞所造成光纖感測器周圍應變場的改變。
本實驗的試片為單搭接膠合接口，搭接物為6061-T6鋁合金，黏膠為Loctite所生產之環氧樹脂結構膠E-30CL。首先透過有限元素分析單搭接膠合接口內之應力、應變場，並配合實測驗證FBG埋放角度與佈放位置的靈敏性，證實FBG以平行於施力方向佈放在搭接長度方向邊緣處具有最佳之破壞偵測效果。其次以拉伸測試、疲勞測試、拉伸破壞後疲勞測試、拉伸破壞後浸入熱水中三十天後再施加循環負載、先高溫低濕三十天後再浸入熱水中三十天後再施加循環負載，證實FBG反射頻譜可偵測到因破壞或是水分滲入所造成之應變場改變。在確認以FBG頻譜偵測膠合接口破壞之可行性後，進一步探討以能量調變法進行以FBG作為濾波器之連動測試、以可調式濾波器與FBG作為濾波器進行動態的拉伸破壞監測、拉伸破壞後疲勞測試以及逐步加載與卸載的測試。結論為將濾波FBG用E-30CL黏貼於搭接物上與感測FBG的連動效果十分良好，而檢光器輸出電壓在拉伸破壞發生時由於應變集中，FBG反射頻譜的飄移量大幅提升，導致調變電壓值有突然升高的現象。

關鍵字

單搭接膠合接口 ； 光纖光柵感測器 ； 結構完整性監測 ； 疲勞損傷監控 ； 環氧樹脂結構膠

並列摘要

The performance of adhesives has made great progress in recent years, so now adhesives are not only used for secondary structures but also applied to some primary structures. Although adhesives are widely used in industries now, the research on monitoring the integrity of adhesive joints is still at an early stage and lack complete study. One of the advantages of fiber Bragg grating (FBG) sensors is its capability of being embedded into the structure. So this thesis adopted FBG to monitor the variation of the strain filed caused by damage around the embedded FBG sensors.
This research used single lap joints (SLJ) as the testing specimens. The adherend was 6061-T6 aluminum alloy and the adhesive was epoxy resin E-30CL manufactured by Loctite. At the beginning of the experiment, finite element analysis (FEA) had been carried out to study the stress and strain distribution in the adhesive. The angular sensitivity and embedded position sensitivity were also investigated by experiments. The results show that the FBG which embedded near the edge of the overlap length direction and parallel to the load direction has the best sensitivity to the damage detection.The follow-up experiments including tensile test, fatigue test, fatigue test after tensile damage has occurred, fatigue test after tensile damage has occurred then immersed the specimens into hot water for 30 days, fatigue test after the specimens have been placed in a high temperature and low humidity environment for 30 days then immersed in hot water for 30 days. The conclusion is that the FBG reflected spectrum could detect the change in strain filed caused by tensile, fatigue and moisture damage. After the feasibility of using FBG sensors to detect the damage in the adhesives had been confirmed, the test of interactive effect by using FBG as the filter, the dynamic tensile test by using adjustable filter and FBG as the filters, the fatigue test after tensile damage has occurred and raise the load step by step and unloading had all been experimented by using energy modulation method. The conclusions are that the interactive effect could well achieved by using FBG pasted in E-30CL on the top of the adherend, and the modulation voltage will suddenly rise when the damage has occurred because of the strain concentration effect.

並列關鍵字

Single lap joint ； Optical fiber grating sensor ； Structural health monitoring ； Fatigue damage monitoring ； Epoxy resin structural adhesive

參考文獻

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