oa FDFD Simulation for High Resolution Eddy-current Testing Method

The applicability and the feasibility of eddy-current testing method for the detection of wall thinning and surface crack of steel structure have been practically confirmed by field and laboratory experiments. Qualitative analysis of cracks has been empirically understood by this method. There has, however, been a growing demand to quantitatively evaluate the cracks and we are inspired to use time series of induced magnetic field induced in the vicinity of cracks. For this objective, we first developed a numerical simulator for the high accuracy eddy-current method. As a result, the effect of surface cracks of a steel plate to magnetic field was confirmed as follows: the induced magnetic field intensity increases near the edge of cracks and decays above the cracks with the distance to the edge. The deeper and wider cracks become, the more the magnetic field intensity is attenuated. Due to the limitation of our simulation schemes, the response of magnetic field intensity whose detectable scale of cracks was no smaller than mm order in 2D simulation. We are introducing a method that could allow us to confirm much finer detectability.