Method of non-destructively testing, a system and a computer program product

摘要

A method of non-destructively testing a magnetisable conducting object surrounded by a magnetisable layer wherein the field strength of a primary magnetic field that is applied exterior to the magnetisable layer is abruptly changed. A vanishing secondary magnetic field generated by eddy currents induced by the changed field strength of the primary magnetic field is received and the temporal field strength of the received secondary magnetic field is analysed for deriving characteristics of the magnetisable conducting object. Furthermore, a transient tertiary magnetic field exterior to the magnetisable layer when the field strength of the primary magnetic field abruptly changes is applied wherein the orientation of the primary and tertiary magnetic field, respectively, are mutually opposite.