Patent ID: 7519487
Filing Date: 2009-04-14
Classification: G01N

Abstract:
1. An improvement to a method for non destructive testing of an object by determination of depth of surface penetrating crack in said object that comprises applying alternating current to a sample; measuring voltage drop V 1 (f) between two probes separated by a gap of distant Δ and making electrical contact with the surface of the sample for at least one frequency f, wherein said probes are located remove from the surface penetrating crack; measuring voltage drop V 2 (f) between two probes separated by a gap of distance Δ and making electrical contact with said surface of said sample, for at least same frequency f, wherein said probes are located at different sides of said surface penetrating crack; and calculating δ based on electrical parameters of said samplers material, the improvement comprising the steps of: determining the depth d of said surface penetrating crack from the equation: wherein and and wherein: where μ r is the relative magnetic permeability; μ rejecting said object based on said determined depth.