Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Treść strony

Reduction of the Velocity Impact on the Magnetic Flux Leakage Signal

The velocity effect on the magnetic flux leakage (MFL) signal was investigated in this paper. Experiments were performed for velocity of the MFL tool within the range of 0–2 m/s. The velocity was not constant during each measurement to imitate real operational conditions of the MFL tool. Two components of the leakage were measured, i.e. the tangential to the motion direction (x) and the normal to the investigated surface (z). In addition to them, the gradient of the normal component in xdirection was measured with the use of two adjacent sensors. The normal component was found to be the most sensitive to the velocity effect. It was shown that the baseline value of the normal component is proportional to the velocity. An empirical compensation scheme was formulated, and it was used to minimize distortions of the normal component caused by the veloc-ity effect. The finite element method was used to study the distribution of velocity-induced eddy currents in the investigated plate. It was stated that eddy currents generated below the poles lead to a change of plate magnetization as well as to a change of magnetic field distribution above the top surface of the plate, what is observed as a shift of the MFL signal baselines.

Authors