EDDY CURRENT DISTRIBUTION USING PARAMETERS NORMALIZED BY STANDARD PENETRATION DEPTH

摘要

The eddy current decays less near the back surface of the test material. The eddy current induced by a pancake coil cancels of itself under the coil. Thus tangential coils can induce eddy current deeper than pancake coils especially when the standard penetration depth is comparable to the plate thickness. As a result, eddy current testing can detect back surface flaws with higher sensitivity with tangential coils than with pancake coils.