ANALYSIS OF THE SPECTRA OF THE EMF OF A TRANSDUCER IN THE MAGNETIC MONITORING OF INTERNAL DEFECTS IN ARTICLES

The spectral composition of the emf of an induction transducer in the magnetic monitoring of defects in the form of cylindrical openings lyi ng at different depths under the surface of an article when it is simu ltaneously magnetized by alternating and constant magnetic fields is i nvestigated. It is shown that the spectral composition of the emf of d efective and defect-free parts of a specimen differ considerably. A ch ange in the spectrum is observed not only in the region of the defect, but also in the defect-free parts close to it. The spectral compositi on of the emf of a transducer, and also the topography of different ha rmonic components depend on the depth of the defect under the surface and on the value of the applied constant field. It is shown that an an alysis of the harmonics of the emf of the transducer can be used to in crease the information content of the magnetic method of flaw detectio n.