Research On The Eddy Current In-Situ Testing Of The Aperture Cracks On The Labyrinth Disc

This paper studies the NDT methods for labyrinth disc. The labyrinth disc is a very crucial part of the aero-engine. It is connected with high-pressure compressor by multiple bolts, and the main function is to prevent air leakage to the unloading cavity. Fatigue cracks easily occur at the aperture, under the coupling effects of the bending vibration stress and radial stress. It is very important to inspect the labyrinth disc in aero-engine regularly to avoid accident.After analyzed several NDT methods, eddy current in-situ testing method is proposed. The test result of this method is consistent with dye penetrant inspection which needs to decomposition the engine. Moreover, it could avoid the scratch caused by decomposition and decrease the cost.We also design a in-situ eddy current NDT testing system. The hardware contain eddy current probe, hand-held pole, eddy current testing instrument. Developed signal processing module, the accurate of the testing system was guaranteed by system calibration. In-situ eddy current NDT testing system could effectively inspect the labyrinth disc in service; the results are stable and reliable.It made a significant contribution for the engine trouble shoot by using in-situ eddy current NDT testing system, serious failure is prevented after troops to use this inspection method. It was confirmed the crack detection accuracy reached 100%.