High-speed inspection of rolling contact fatigue in rails using ACFM sensors

High-speed ACFM tests were carried out using a rotary test-piece that contained spark-eroded notches. The ACFM sensor detected the induced notches at 121.5 km/h while the recorded signal intensity remained largely unaffected by the increases in speed under constant lift-off. To simulate actual rail inspection conditions at high speed,further tests were carried out using a spinning rail rig and a set of rails that contained spark-eroded notches of various shapes and sizes lip to a speed of 48 km/h. The ACFM sensor successfully detected the artificially-induced notches, however the signal was affected by severe lift-off variations that occurred during testing.