TRANSVERSE CRACK DETECTION IN RAIL HEAD USING LOW FREQUENCY EDDY CURRENTS

摘要

A method and system for detecting transverse cracks (50) beneath horizontal cracks (40) in the rail way track (90). As a transporter (110) moves over rail (90), a saturation magnetic field (170) is generated into and across the rail head (10) using a toroidal­shaped DC saturation magnet (140) located a predetermined distance above the rail head (10). Any transverse cracks (50) in the rail head (10) are detected with a low frequency eddy current probe (150) mounted centrally between the opposing pole ends (142) of the DC magnet (150) and over the rail head (10). A force is applied to the low frequency eddy current probe (150) to hold the probe towards the rail head (10) as the transporter (110) moves on the rail (90) so as to follow the wear pattern of the rail head (10) and to minimize lift-off. A second sensor (1000) is used to sense the presence of non-relevant indications that falsely indicate possible transverse cracks (50) by the low frequency eddy current probe (150).