R区是复合材料结构中的重要几何过渡区和连接区, 利用超声反射法检测时, 入射声波在R区形成的反射信号的复杂性明显影响了缺陷的判别和评定。为此, 采用宽带窄脉冲超声检测方法, 通过专门设计的超声检测系统及水膜耦合换能器, 提取和分析来自实际复合材料结构R区的超声反射信号的时域特征, 结合超声检出结果进行解剖验证分析。结果表明: 采用水膜耦合可以获得较好的声学耦合效果和稳定的超声反射信号; 来自R区分层等缺陷和R区层间界面及树脂界面的反射信号在其单周特性、幅值特性、多次反射行为等方面存在明显的时域差别, 基于此特征, 可有效地进行复合材料R区缺陷的判别和定位, 并有效地检出R区近表面单个铺层深度(约0.13 mm)的分层; 基于此信号特征的B扫描为复合材料结构中R区缺陷的检测与评估提供了一种非常直观的可视化方法。

R-zones are the important geometric transition and joint region of composite primary structures. The complexities of echo signals from R-zones bodies have effects on the discrimination and evaluation of defects when ultrasonic reflection method is used. Therefore, a broad-band short pulsed ultrasonic method was employed to obtain echo signals from series of R-zones in practical carbon fiber-reinforced composite structures by using a special ultrasonic system and transducer with water-film coupling. Time-domain characterizations of the echo signals were analyzed. A series of destructive testing were implemented for validating the correction of the ultrasonic results. The testing results have shown that good ultrasonic coupling and high quality echo signals can be obtained by using the water-film transducer and the ultrasonic system; there are obvious time-domain differences of echo signals from delaminations and interlaminar ply interfaces as well as from resin interfaces in periodic property, amplitude and multiple reflection behavior. These differences in echo signals provide a very effective and easy way to discriminate and position defects in R-zone by using B-scan, which has been applied to practical nondestructive testing and evaluation of series of R-zones in composite structures. The delamination with 3 mm in diameter and single prepreg ply depth (approximately 0.13 mm)can be found out by the method.