Noncontact Detection of Air Voids Under Glass Epoxy Jackets Using a Microwave System
Noncontact Detection of Air Voids Under Glass Epoxy Jackets Using a Microwave System
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使用微波系统非接触式检测玻璃环氧树脂护套下的气孔
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
C. Liu
中科院分区：
文献类型：
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作者：
Jing Li;C. Liu
玻璃环氧树脂护套通常用于加固混凝土桥环。粘合材料中的空气空隙将降低玻璃环氧树脂增强套环的机械强度。为了检测桥梁环和玻璃环氧护套之间的空气空隙，已经设计并实现了一个聚焦微波成像系统。开发了一种用于从测量的电磁信号中反演介电常数的算法，以成像空气空隙的大小和位置。所开发的微波系统工作在10 GHz，具有一个发射机和一个接收机。为了提高空间分辨率，介质透镜被用来聚焦来自天线的微波束。在测量中，传感器系统机械地围绕具有玻璃环氧树脂护套的混凝土套环转动。以2度间隔测量二维信号。然后通过反转二维信号获得键合层上的介电常数分布。制备了具有已知空气空隙的复合材料护套的实验室样品，以验证所开发的系统。键合层上的介电常数的反转分布与实际的脱键分布在位置和尺寸上都非常一致。本文详细介绍了反演理论和硬件系统。
Glass epoxy jackets are commonly used to reinforce concrete bridge collars. Air voids in the bonding materials will degrade the mechanical strength of the glass epoxy reinforced collars. In order to detect air voids between a bridge collar and a glass-epoxy jacket, a focused microwave imaging system has been designed and implemented. An algorithm for inverting the dielectric constants from the measured electromagnetic signals was developed to image the size and location of the air voids. The developed microwave system operates at 10 GHz with one transmitter and one receiver. To increase the spatial resolution, dielectric lenses were used to focus the microwave beam from antennas. In the measurement, the sensor system was mechanically turned around the concrete collar with glass epoxy jackets. Two-dimensional signals were measured at 2-degree intervals. The dielectric constant distribution over the bonding layer was then obtained by inverting the two-dimensional signals. A lab sample of composite jacket was prepared with known air voids to verify the developed system. The inverted distribution of the dielectric constants over the bonding layer agreed very well with the actual distribution of the disbonds in both positions and sizes. In this paper, we present the details of the inversion theory and also the hardware system.