Eddy Current Detection and Tip Location of Defects in Aircraft Bearing Parts

Eddy current testing technology applied for surface or near-surface cracks in aviation aluminum alloy is fast and does not require a coupling agent. Nevertheless, the detection sensitivity is low due to the negative influence of the adhesive layer. Fatigue cracks initiated by stress concentration during the service of the aircraft can easily lead to the structural failure in airframe. Therefore, the integrity of the bearing components is one of the key factors to ensure the flight safety of the aircraft. Aiming at the fatigue cracks of the bearing component, a method of defect tip location based on the double-line length measurement was proposed. A special double-line eddy current shielding probe for tiger-crack defects was designed, which can adaptively locate the installation error of bolts. The results show that the self-adaptive positioning bolt is used to fix the measuring device at the tiger mouth, and the double-line measuring device at the crack tip can effectively locate the crack. When the excitation frequency ranges from 30 to 40 kHz, the developed double-line eddy current shielding probe can sensitively detect 7.0 mm × 0.2 mm ( radius × width ) fan-shaped artificial grooves under the adhesive layer.