Noise isolation with phononic crystals to enhance fatigue crack growth detection using acoustic emission
Noise isolation with phononic crystals to enhance fatigue crack growth detection using acoustic emission
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DOI：
10.1007/s13349-018-0291-6
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发表时间：
2018-06
影响因子：
4.4
通讯作者：
M. Kabir;A. Mostavi;D. Ozevin
中科院分区：
文献类型：
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作者：
M. Kabir;A. Mostavi;D. Ozevin
背景噪声给结构声发射实时监测中的裂缝活动监测带来困难。本文设计了一种二维声子晶体（PC），以提高声发射技术在类板结构中疲劳裂纹扩展的检测能力，使单个声发射传感器足以监测裂纹活动。pc，也被称为声学超材料，是一种人造合成材料，人造周期系统通过组成材料的物理限制产生新的响应，使得某些频率被周期系统的局部共振所禁止。将PC设计与声发射方法相结合，可以有效地屏蔽不需要的噪声信号，提高声发射方法的裂纹检测能力。采用COMSOL Multiphysics软件，通过单元分析和传输损耗两种方法，对所提出的PC结构进行了数值研究。结果表明，所设计的PC结构产生带隙的主要原因是局域共振现象。最终的几何形状被选择为提供接近150khz的带隙，这是监测金属结构中裂纹扩展的常用频率。除了沿着裂纹生长路径和传感器位置外，形成PC结构的短桩定期放置在致密试样上，以阻止来自握把位置的摩擦排放。通过铝标准压紧拉伸试件的疲劳试验，验证了所设计的PC结构的性能。结合PC结构获得的累计命中数和声发射能量表明，噪声阻断技术在主动裂纹声发射测试中的成功实施。
The background noise imposes difficulties in monitoring crack activities in real-time monitoring of structures using the acoustic emission (AE) method. Here, a two-dimensional phononic crystal (PC) is designed to enhance fatigue crack growth detection capability of acoustic emission technique in plate-like structures, such that a single AE sensor is sufficient to monitor the crack activity. PCs, also known as acoustic metamaterials, are artificial composite, man-made periodic systems creating new responses through physical constraints in the constituent materials such that certain frequencies are prohibited by local the resonance of the periodic system. The integration of PC design with AE method can be utilized to block unwanted noise signals and enhance the crack detection ability of the AE method. The proposed PC structure to block certain frequencies is numerically studied using COMSOL Multiphysics software through applying two approaches: the unit cell analysis and the transmission loss. It is concluded that the primary reason of the band gap formation through the designed PC structure is the local resonance phenomenon. The final geometry is selected to provide a band gap near 150 kHz, which is a common frequency to monitor crack growth in metallic structures. The stubs forming the PC structure are placed on the compact specimen periodically, except along the crack growth path and sensor position, to block the friction emissions coming from the grip locations. The performance of the designed PC structure is demonstrated experimentally through the fatigue testing of aluminum standard compact tension specimens. The cumulative numbers of hits and AE energy obtained from the specimen integrated with the PC structure demonstrate the successful implementation of noise blocking in the AE testing of detecting active cracks.