Patent ID: 9103802
Filing Date: 2015-08-11
Classification: G01N

Abstract:
1. A method of determining a crack depth of a crack in a metallic material, the method comprising: feeding a current with a first magnitude to a transmitter coil for generating a magnetic field in the metallic material, controlling the current such that it obtains a second magnitude when the magnetic field is estimated to have penetrated deeper than a deepest crack depth desired to be measured in the metallic material, detecting the magnetic field by means of a receiver coil, which detected magnetic field thereby generates a signal in the receiver coil, determining a first characteristic value of the signal in a first time range, the first time range starting at a time: determining a second characteristic value of the signal in a second time range after the first time range, and determining a possible presence of a crack and its crack depth based on the first characteristic value and the second characteristic value.