3-D nonlinear analysis of effect of air gap between yoke and steel in alternating flux leakage testing

Abstract

The alternating magnetic flux leakage testing has been applied in the inspection process for detecting cracks on the surface of steel. This testing detects the leakage flux from the cracks in ferromagnetic material magnetized by the AC electromagnet. The signal is affected by the construction of the equipment. In this paper, the effect of the air gap between the yoke and the steel plate on the leakage flux and the phase angle between the flux of a search coil and the exciting current are investigated using 3-D alternating nonlinear edge-based hexahedral finite element method.