Numerical simulations on electromagnetic NDT at high speed

Magnetic flux leakage method (MFL) and eddy current method (ECT) are typical electromagnetic non-destructive testing (NDT) methods used for non-destructive evaluation. The two methods are complementary in terms of defect detection and material characterisation capabilities. There is a great demand in online metal evaluation and defect characterisation such as pipeline and rail track. At high speed measurement of MFL, in addition to magnetic flux, eddy currents exist in metal specimen. These currents alter the profile of electromagnetic field and increase difficulty in signal interpretation and defect characterisation. In this paper, eddy currents generated by high-speed movement and their characterisation in high-speed MFL inspection systems are investigated by using numerical simulations. Similarly, the signal responses to surface defects from ECT inspection systems are also analysed. Simulation conclusions are presented