3-D Displacement Measurement for Structural Health Monitoring Using Low-Frequency Magnetic Fields
3-D Displacement Measurement for Structural Health Monitoring Using Low-Frequency Magnetic Fields
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DOI：
10.1109/jsen.2016.2636451
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发表时间：
2017-02
影响因子：
4.3
通讯作者：
O. Kypris;A. Markham
中科院分区：
文献类型：
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作者：
O. Kypris;A. Markham
未来的智能结构将需要一种经济高效、易于部署的结构健康监测解决方案。结构上的高载荷会产生应力，可能导致间隙扩大，这对整体结构健康至关重要，因为它们会吸收多余的应力。现有的伸缩缝直接位移测量方法并不理想，因为它们在视线假设下操作，对水分敏感，或者使用移动部件。此外，大多数用于结构健康监测的现有传感器是单轴的，因此从根本上无法测量3-D位移。重要的是，现有的结构健康监测无线传感器都不能嵌入混凝土中。我们提出了一个系统，使用低频磁场进行3-D位移测量直接从混凝土内，在所有方向上的位移误差为0.5毫米的中位数，与50毫米的最大间距之间的发射器和接收器。传感器可以在建筑物竖立后附接到混凝土表面，或者可以包括在制造时的混凝土混合物中，以监测伸缩缝中的间隙之间的位移，在铁路和人行道的混凝土轨枕中执行裂缝检测，以及辅助预制混凝土块的组装的位置测量。嵌入混凝土允许在结构的整个寿命期间运行，提供即将发生的灾难的早期预警，并帮助通知维修操作。
Smart structures of the future will require a cost-effective, easily deployable solution for structural health monitoring. High loads on structures cause stresses that may lead to expansion of gaps, which are of utmost importance when it comes to overall structural health, as they absorb excess stress. Existing methods for direct displacement measurement of expansion joints are not ideal, as they operate under line-of-sight assumptions, are sensitive to moisture, or employ moving parts. In addition, the majority of existing sensors for structural health monitoring are uniaxial, and hence are fundamentally unable to measure 3-D displacement. Importantly, none of the existing wireless sensors for structural health monitoring can be embedded in concrete. We propose a system that uses low-frequency magnetic fields to conduct 3-D displacement measurement directly from within concrete, with a median displacement error of 0.5 mm in all directions, with a maximum separation distance of 50 mm between the transmitter and the receiver. The sensors can be attached to the concrete surface after the building is erected, or can be included in the concrete mix at manufacture, to monitor displacement between gaps in expansion joints, perform crack detection in concrete ties for railroads and in pavements, as well as aid position measurement for the assembly of premanufactured concrete blocks. Embedment in concrete allows operation throughout the lifetime of a structure, providing early warning of impending disaster and helping to inform repair operations.