Defect inspection of braided carbon fiber reinforced polymer (CFRP) is very difficult due to its nonhomogeneity, anisotropy, and sensitivity to coupling agents. This paper presents a hybrid system for detecting microstructure and defects in braided CFRP that combines the advantages of laser-ultrasound and air-coupled ultrasonic testing. Through the finite element method, the ultrasonic field propagating on the braided CFRP was simulated during the laser-induced ultrasound, and the influences of laser parameters and surface braided structure were analyzed on the laser ultrasonic signal. This detection method based on air-coupled laser ultrasound can provide the near-surface microstructure characterization of the resin pockets and braided fiber bundles, and also can achieve both shallow and deep defect detection of CFRP sheets which is comparable to that of the contact-type high-frequency phased array with higher contrast and less distortion. These results indicate that it has the potential to develop a non-contact, high-resolution, and low-cost method for the detection and repairment of advanced composite materials.

由于编织碳纤维增强聚合物 (CFRP) 的不均匀性、各向异性和对偶联剂的敏感性，其缺陷检测非常困难。本文提出了一种混合系统，用于检测编织碳纤维复合材料的微观结构和缺陷，该系统结合了激光超声和空气耦合超声检测的优点。. 通过有限元方法，模拟了激光诱导超声过程中在编织CFRP上传播的超声场，分析了激光参数和表面编织结构对激光超声信号的影响。这种基于空气耦合激光超声的检测方法可以提供树脂袋和编织纤维束的近表面微观结构表征，也可以实现与接触式相当的CFRP片材的浅层和深层缺陷检测。高频相控阵，对比度更高，失真更小。这些结果表明，它具有开发一种非接触式、高分辨率、低成本的先进复合材料检测和修复方法的潜力。