This paper proposes a new microwave non-destructive testing (NDT) method based on liquid flow controlled spoof surface plasmon polaritons (SSPPs) to detect defects in non-metallic composites. The sensor based on this method is composed of SSPPs structure and liquid flow controller. The liquid flow controller can be used to control the sensing area of the sensor. The detection is based on the change of the transmission coefficient at the cut-off frequency of SSPPs sensor, which is caused by defects. Since liquid movement has continuity, the sensor’s field distribution is also continuous change. So in a certain detection range, the liquid flow scanning method can avoid the problem of defect missing detection. Taking FR4 as an example, both the simulation and experiment results reveal that this liquid flow controlled SSPPs sensor can effectively realize defects detection with a radius of 1mm in non-metallic composites. The sensor has the advantages of simple structure, easy operation, fast detection speed and convenient detection of curved MUT.

中文翻译：

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基于液流控制欺骗表面等离子体激元的非金属复合材料缺陷检测方法


本文提出了一种基于液体流控制欺骗表面等离子体激元（SSPP）的新微波无损检测（NDT）方法，用于检测非金属复合材料中的缺陷。基于该方法的传感器由SSPPs结构和液体流量控制器组成。液体流量控制器可用于控制传感器的感应面积。该检测基于SSPPs传感器在截止频率处由缺陷引起的传输系数的变化。由于液体运动具有连续性，传感器的场分布也是连续变化的。所以在一定的检测范围内，液流扫描方式可以避免缺陷漏检的问题。以FR4为例，仿真和实验结果表明，这种液体流量控制的SSPPs传感器可以有效实现非金属复合材料中半径1mm的缺陷检测。该传感器结构简单、操作方便、检测速度快、方便检测弯曲的MUT。