The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 11, 1989
Filed:
Nov. 24, 1986
Gerhard Huschelrath, Laufach--Frohnhofen, DE;
Nukem GmbH, Hanau, DE;
Abstract
The object of the invention is a method and a device for materials testing using the eddy-current principle. If a coil (30) is moved in relation to test specimens, magnetic alternating fields with differing frequencies are generated, these fields induce eddy-currents that cause a secondary field in the coil (30). A number of test specimens having the same structure and the same dimensions are measured. The measured values are stored. The coordinates of the center of gravity of the measured values in the complex plane are then determined. The the phase angle is determined of that axis which runs longitudinally through the field (20) formed by the measured values in the complex plane. The center of gravity is then rotated into the origin of the coordinate system and the axis into a coordinate axis. Then a threshold value envelope determining a fault boundary is placed around the field of the measured values. The threshold value curve is then displaced by the coordinates of the center of gravity and rotated by the phase angle of the axis. In later measurement of test specimens for fault detection, the measured values are directly compared with the values of the transformed threshold value envelope.