Im Kwang-Hee, Kim Sun-Kyu, Jung Jong-An, Cho Young-Tae, Woo Yong-Deuck, Chiou Chien-Ping
Department of Automotive Engineering, Woosuk University, Chonbuk 565-701, Korea.
Division of Mechanical System Engineering, Chonbuk Natl. University, Jeonbuk 561-756, Korea.
Materials (Basel). 2019 Apr 17;12(8):1264. doi: 10.3390/ma12081264.
For many years, scientists have been aware of the importance of terahertz waves (T-rays), which have now emerged as an NDE (nondestructive evaluation) technique for certain ranges of the electronic spectrum. The present study deals with T-ray scanning techniques of honeycomb sandwich composite panels with a carbon-fiber-reinforced plastic (CFRP) skin as well as the refractive index (), and the electrical conductivity () of glass fiber-reinforced plastic (GFRP) composites. For this experiment, the degree of penetration to FRP composites is investigated for the THz transmitted power based on the angle in the electric field (E-field) direction vs. the direction of the unidirectional carbon fibers. Also, when CFRP skin honeycomb sandwich panels are manufactured for use in aerospace applications, aluminum wires are twisted together into the one-sided surface of the honeycomb sandwich panels to protect against thunderstorms. The aluminum wires are partly visible because they are embedded in the CFRP skin on the honeycomb sandwich panels. After finishing work with a paintjob, the wires become invisible. Thus, detecting the aluminum wires is a key issue for product monitoring. Based on a simple resistor model, an optimal scanning method is proposed to determine the preferred scan orientation on the baseline of the E-field in the direction of fibers to evaluate the level of transmission of T-rays according to the frequency bandwidth. Thus, the combination of angles required to detect the aluminum wires embedded with carbon fibers on the surface of the composite panels can be determined.
多年来，科学家们已经意识到太赫兹波（T射线）的重要性，如今太赫兹波已成为电子频谱特定范围的一种无损检测（NDE）技术。本研究涉及以碳纤维增强塑料（CFRP）为蒙皮的蜂窝夹层复合板的T射线扫描技术，以及玻璃纤维增强塑料（GFRP）复合材料的折射率（）和电导率（）。对于本实验，基于电场（E场）方向与单向碳纤维方向的夹角，研究了太赫兹透射功率对FRP复合材料的穿透程度。此外，当制造用于航空航天应用的CFRP蒙皮蜂窝夹层板时，铝线被绞合到蜂窝夹层板的单面以防雷。铝线部分可见，因为它们嵌入在蜂窝夹层板的CFRP蒙皮中。在完成喷漆工作后，这些线就看不见了。因此，检测铝线是产品监测的一个关键问题。基于一个简单的电阻模型，提出了一种优化扫描方法，以确定在纤维方向的E场基线上的首选扫描方向，从而根据频率带宽评估T射线的传输水平。因此，可以确定检测复合板表面嵌入碳纤维的铝线所需的角度组合。
