블리드에어덕트의 자동결함탐상에 관한 연구

Abstract

In this paper, the unmanned recognition algorithm of defect on the bleed air duct and 360° coverage performance of non-destructive inspection system composed of bobbin coil and annular array magnetic sensor is reported. When an alternating current is applied to the bobbin coil, an induced current is generated in the direction of the arc of the specimen. The induction current is distorted by the crack generated in the circumferential direction of the specimen, and eddy currents are generated at both ends of the defect. Thus, the time-varying magnetic field strength in the radial direction changes at both ends of the defect. On the other hand, the Hall sensors are arranged at intervals of 8.18 degrees. Therefore, if the crack passes between the sensor and the sensor, the defect detection capability may be degraded. In this study, the relationship between the spatial resolution of the sensor and the 360 degree coverage performance was experimentally investigated while turning the specimen at 0 degree intervals. The specimen is a titanium bleed air duct with an inner diameter of 38 mm and a thickness of 0.45 mm.