Scanning magnetic microscopy model analysis of circular flaws in thin metallic plates

We studied the eddy currents excited by a time varying external magnetic field in thin metallic plates in the presence of a circular hole piercing the plate. The value of the normal component of the magnetic field over the circular defect is analytically calculated and a complete scanning magnetic operation along a line crossing the defect is simulated. The analytical solution is then tested against a direct numerical simulation with good results. The aim is the reconstruction and interpretation of magnetic signatures due to structural defects in nondestructive evaluation made by superconducting quantum interference device microscopy measurements. © 2009 American Institute of Physics. doi:10.1063/1.3272720