Simulation and experimental study on MFL-based damage detection capability considering velocity condition for railroad NDE

This paper used a magnetic flux leakage (MFL) method compatible with steel structures to analyze quantitative change in a leakage signal due to defects on the surface of a railroad. A numerical simulation using a two-dimensional finite element method (2D-FEM) was used to analyze MFL signals from defects on the railroad. An experiment was then carried out to investigate the capability of the MFL-based non-destructive evaluation (NDE). We also focused on the velocity effect of the MFL signals by analyzing the magnetic hysteresis phenomenon. The quantitative change in leakage signals was determined by selecting depth of the defect and inspection velocity as parameters in a simulation and in an experiment. The MFL signals obtained showed variations that were simultaneously affected by inspection velocity and defect depth. MFL-based damage detection in a railroad is conclusively confirmed to be sufficiently feasible within the range of operational speeds of an inspection train.