METHOD AND APPARATUS FOR NON-DESTRUCTIVE TESTING OF MAGNETICAL PERMEABLE BODIES

摘要

ABSTRACT OF THE DISCLOSUREThe present invention relates to a method andapparatus for non-destructive comparative investigationof physical characteristics affecting the reluctance ofdifferent parts of a body having magnetic permeability.In accordance with the present invention a firstsaturating magnetic flux is induced in the body or a partthereof giving rise to a flux distribution patterndetermined by the reluctance of the body or part thereofwhich in turn is determined by the physical character ofthe body or body part. A second magnetic flux is alsoinduced generally opposing the first magnetic flux in aselected region of the flux distribution pattern outsideof the body or body part while maintaining substantialfirst flux saturation of the body or body part, such thatany resultant magnetic flux in that region is at areadily measureable flux level. Also provided is adetector for detecting along the body either variancesfrom that flux level with the second magnetic flux beingmaintained substantially constant or variances of thesecond magnetic flux with the resultant magnetic fluxbeing maintained substantially constant.