Fiber optic sensor for the monitoring of mixed mode cracks in structures
Fiber optic sensor for the monitoring of mixed mode cracks in structures
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DOI：
10.1016/j.sna.2006.08.002
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发表时间：
2007-04
影响因子：
4.6
通讯作者：
K. Wan;C. Leung
中科院分区：
文献类型：
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作者：
K. Wan;C. Leung
在一般荷载条件下，结构中的裂纹可能以混合模式张开。换句话说，沿裂纹沿着既有张开位移又有剪切位移。在我们以前的工作中，分布式光纤传感器已被开发用于检测和监测纯开放裂纹（或模式I裂纹）。传感原理是基于以非90°的角度与开口裂纹相交的光纤的弯曲损耗。在目前的工作中，传感的概念扩展到监测的混合模式裂纹。为了获得裂纹处的张开位移和剪切位移，需要进行两次独立的测量。基于理论模拟，各种传感策略的可行性，包括使用两个波长和两个光纤，首先研究，以确定最有前途的方法。然后推导出一种解决由测量信号损失获得裂纹位移的逆问题的方法。控制裂纹张开/剪切历史下进行的实验，以验证传感方法。导出的张开/剪切位移和施加的位移之间已经获得了良好的协议。
Cracks in structures may open in mixed mode under general loading conditions. In other words, there are both opening and shearing displacements along the crack. In our former work, a distributed fiber optic sensor has been developed for the detection and monitoring of purely opening cracks (or Mode I cracks). The sensing principle is based on the bending loss of an optical fiber intersecting the opening crack at an angle other than 90°. In the present work, the sensing concept is extended to the monitoring of mixed mode cracks. To obtain both the opening and shear displacements at the crack, two independent measurements are required. Based on theoretical simulation, the feasibility of various sensing strategies, including the use of two wavelengths and two fibers, are first investigated to identify the most promising approach. A method to solve the inverse problem of obtaining the crack displacements from the measured signal losses is then derived. Experiments are performed under controlled crack opening/shearing history to verify the sensing approach. Good agreement between derived opening/shearing displacements and imposed displacements has been obtained.