The metal thickness detection using pulsed eddy-current computation and detection method

Through detecting method of pulsed eddy-current (PEC) and according to thickness testing model of multi-layer metal, infer the mathematical model of eddy current testing method in single-layer metal. Use Maxwell field equations to find solutions of vector magnetic potential in its boundary conditions thus infer the impedance of hollow coil placed right above metal. Analyze the variation relationship between induced current and metal thickness in theory level. (1) Obtain three characteristic signals of induced current: altitude of current peak value (ACPV), time of reaching current peak (TRCP) and time of traversing zero point (TTZP). The thickness of the metal and the distance between the metal and coil were obtained. (2) Introduce the concept of the lift-off intersection point (LOI) and puts forward a new method of metal thickness detection based on the LOI. By analyzing the results of the experiment, it confirms the feasibility of the LOI of measurement in the metal thickness.