基于涡流成像的碳纤维增强树脂基复合材料细观结构可视化

对碳纤维增强树脂基复合材料（CFRP）的细观结构成像方法进行了研究，利用涡流成像技术实现了CFRP层合板中纤维方向及纤维缺失、褶皱和空隙过大等缺陷的可视化。首先通过有限元仿真和电路理论分析了CFRP板中涡流的生成机制和分布特性，阐述了基于涡流法的CFRP细观结构成像机制。然后介绍了用于扫描成像的高频涡流检测（HF-ECT）实验系统并确定了涡流探头的形式及其参数。最后利用涡流成像技术分别对单层板、正交层合板和四方向斜交层合板进行了检测，绘制了涡流检测（ECT）信号的三维伪彩图并得到了清晰的纤维纹路分布。通过引入滤波去噪技术和二维快速傅里叶变换（2D-FFT）对图像进行进一步处理，提高了图像分辨率并完成了不同方向上纤维纹路的分离，从而实现对层合板每单向层中缺陷的精确定位。

Visualization of meso-structure of carbon fiber reinforced polymer based on eddy current imaging

The imaging of meso-structures within carbon fiber reinforced polymer (CFRP) composites was studied. The visualization of fiber orientations and defects such as missing bundles, wrinkle and gaps in CFRP laminates were realized by using eddy current imaging technique. Firstly, the mechanism and distribution of eddy currents in CFRP plates were analyzed by finite element simulation and circuit theory. The imaging mechanism of CFRP meso-structure based on eddy current method was also described. Then the high frequency eddy current testing (HF-ECT) experimental system for scanning imaging was introduced, and the form and parameters of the eddy current probe were determined. Finally, the eddy current imaging technique was used to detect the unidirectional plate, the orthogonal laminate plate and the four-directional angle-ply laminate plate. The three-dimensional pseudo-color images of the eddy current testing(ECT) signals were plotted and clear fiber textures were obtained. The images were further processed by introducing the filter denoising technique and the two-dimensional fast Fourier transform (2D-FFT) to improve the image resolution and complete the separation of the textures in different directions, so as to realize the accurate positioning of the defects in the unidirectional layer of the laminates.