DEPENDENCE OF THE RAIL MFL TESTING DATA ON THE SPEED ACCORDING TO THE RESULTS OF COMPUTER SIMULATION AND EXPERIMENT

Abstract

Research of magnetic flux leakage signals of rail non-destructive testing in a wide range of scanning speeds is carried out. The results of three-dimensional computer simulation show significant changes in the distribution of the magnetic field in the depth of the rail at high motion speeds of the magnetizer. The appearance of low magnetization zones in the places most distant from the surface of the rail due to the influence of eddy currents is predicted. It is concluded that to detect defects that lie deep under the surface of the rail, magnetic sensors should be shifted towards the rear pole. The simulation results are in correct agreement with the results of experimental studies carried out on railway tracks at testing speeds up to 60 km/h. The effect of the formation at high scanning speeds of a tail magnetic flux behind the rear pole of the magnetizer is considered. Registration of this flux leakage data is promising from the point of view of detecting deep-seated defects, as well as separating signals from surface and internal flaws at high inspection speeds.