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| Ultrasonic Evaluation and Defect Discrimination of T-Shape R-Zone in Composite Structures |
| LIU Feifei, LIU Songping, FU Tianhang, LI Legang, BAI Jinpeng |
| ( AVIC Composite Corporation Ltd., Beijing 101300, China) |
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Abstract 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 of T-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 tech-nique 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.
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2017, 
