复合材料T-形R区超声反射法检测与缺陷判别

R区缺陷的检测是碳纤维复合材料结构中无损检测的焦点,针对此问题,以T-形R区为例,通过研究入射超声波在复合材料结构T-形R区产生回波信号及其特征,在典型超声检测试验验证分析基础上,提出了一种适用于复合材料结构T-形R区在线超声检测方法。系列超声检测与验证结果表明:采用水膜耦合超声检测技术,通过选择不同的声波入射方向,可有效地实现复合材料结构中T-形R区的覆盖检测;根据来自T-形R区的超声回波信号的时域特征可有效地进行缺陷的判别和确定检出缺陷所在铺层位置;表面检测盲区可达0.13mm(即单个复合材料铺层厚度)。解剖验证结果显示了超声检测结果与实际工艺缺陷的良好一致性。

Ultrasonic Evaluation and Defect Discrimination of T-Shape R-Zone in Composite Structures

Currently,the nondestructive testing and evaluation (NDT & E) of R-zone in carbon fiber-reinforced composite structures (CFRCS) has become a focus in the area.A high-resolution ultrasonic technique was employed for the NDT & E ofT-shape R-zone in CFRCS based on the reflected echo signals and their characterizations by studying the interaction of incident short-pulse ultrasonic wave with T-shape R-zone.Series of ultrasonic testing and destructive testing experiments were carried out.A water-film couple method was used between transducer and T-shape R-zone surface.The incident direction and position of wave beam can be changed through the scanning of transducer and its aided mechanical device for 100％ NDT of T-shape R-zone.Series of experimental and practical results have shown that the ultrasonic technique is very powerful in the NDT & E of T-shape R-zone in CFRCS.Defects and their exact positions in layup direction can be effectively discriminated and quantitatively determined according to the time-resolved reflected echoes from T-shape R-zone laminates and their time-domain characterization.The surface resolution and dead-zone of the ultrasonic method can be reached to 0.13mm,i.e.,the thickness of a single prepreg ply approximately.The series of destructive testing results have excellently demonstrated the correction of ultrasonic results compared with the real defect induced during the manufacturing of the CFRCS with T-shape R-zones.