Process and apparatus for the nondestructive measuring of magnetic properties of a test body, by detecting a tangential magnetic field and deriving harmonic components thereof

US5028869A · kind A · utility

Assignee

• Fraunhofer-Gesellschaft zur förderung der angewandten Forschung e.V. · DE

Inventors

• Gerd Dobmann · Sulzbach/Saar, DE
• Holger Pitsch · Seligenstadt, DE

Key dates

• Filing date: Nov 27, 1989
• Grant date: Jul 2, 1991
• Expiry date: Nov 27, 2009

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/72
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In a process and an apparatus for determining the coercive field strength and the maximum pitch of the hysteresis cure in set-up techniques a test body is magnetized in a magnetic field of an exciter coil fed with an alternating current, as the hysteresis curve of the test body is traversed a number of times with the frequency of the alternating current and the tangential field strength on the test body surface generated by the exciter coil is detected continuously with the aid of a magnetic field strength sensor during the traversing of the hysteresis curve. From a harmonic analysis of the time course of the tangential field strength within one period there is calculated a distortion factor for the determination of the maximum pitch of the hysteresis curve. The coercive field strength is ascertained by the means that the point of time of the first zero passage of the harmonic signal after the zero passage of the tangential field strength signal is sought and the amplitude of the tangential field strength signal present at this point of time is regarded as measure for the coercive field strength.