2504 分布型光ファイバセンサによる溶接部のひずみモニタリング(J10-1 計測・モニタリング・解析(1),J10 知的材料・構造システム)

概要

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Distributed strain sensor with particularly high spatial resolution is required for assessing integrity of welded joint by monitoring its strain distribution. A distributed strain measurement system based on optical frequency domain reflectometry (OFDR) can measure a strain at arbitrary position along a long gauge FBGs (fiber Bragg grating) with high spatial resolution less than 1mm. In this study, we evaluated the applicability of the system to strain monitoring of welded joints in static tensile tests. We could successfully measure the strain distribution along the weld line for 100mm, and could show the process of degradation of the specimen. In addition, we could observe that the strain distribution sharply fluctuates with acoustic emissions in the area where anomalous distortions in the strain distribution were observed under the relatively lower load. We could also measure strain distribution ranged over 8000με within the FBG with gauge length of 100mm. The measured strain was mare than -10000με at maximum. Thus, the system was proved to have excellent spatial resolution and the measurement range sufficient to monitor the strain distribution of the welded joints.
社団法人日本機械学会の論文
2007-09-07