飞机机身多层铆接结构厚度较大，结构复杂，传统无损检测方法难以用于对其进行外场检测。远场涡流检测技术不受集肤效应的限制，可穿透较大厚度的被测试件，对铆接结构中缺陷的检测具有潜在优势。为在铆接结构中实现远场涡流效应，从信号增强与磁场抑制两方面入手，设计一种新型平板远场涡流传感器。信号增强方面，给激励线圈加装磁路来聚集和引导磁场，从而增强间接耦合磁场；磁场抑制方面，在激励线圈与检测线圈之间加装磁场抑制单元来抑制直接耦合磁场。通过信号增强与磁场抑制的共同作用，从而在铆接结中实现远场涡流效应。围绕传感器设计这个核心，对信号增强单元以及磁场抑制单元的尺寸形状、材料组成进行仿真研究，综合得出最优的传感器设计方案。仿真与试验的结果验证了将远场涡流检测技术应用于铆接结构中缺陷检测的可行性。
Since the complexity and large thickness of the fuselage riveted structure, it is difficult to detect its cracks by traditional eddy current testing technology. Without the restriction of skin effect, remote field eddy current can penetrate specimen with large thickness, and has potential to detect cracks in riveted structure. In order to realize remote field eddy current effect in riveted structure, a new remote field eddy current sensor is designed from the aspects of signal enhancement and magnetic suppression. On one hand, magnetic circuit is added to the excitation coil for collection and guidance of excitation magnetic field, enhancing indirect coupling magnetic field; On the other hand, suppression unit is equipped between the excitation coil and the detection coil to restrain direct coupling magnetic field. Remote field eddy current effect is realized through the co-work of signal enhancement and magnetic suppression. Focusing on the design of sensor, many simulations have been carried out on the shape, size and material of the signal enhancement and magnetic suppression unit, and the optimal design is obtained. Simulation and experiments results verify the feasibility of the application of remote field eddy current testing technology in the location detection of cracks in riveted structure.
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