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:
Nov. 24, 1992
Filed:
Nov. 06, 1990
William D Perry, San Antonio, TX (US);
Southwest Research Institute, San Antonio, TX (US);
Abstract
A system for identifying and measuring stress at specific locations within a ferromagnetic material by the production and detection of Barkhausen noise during magnetization of the material. The method involves introducing into the material a time varying magnetic field component and a spatially-varying magnetic field component that in combination create a singular zero magnetic flux element within the material that 'sweeps' from one position within the material to another and back. By time-gating the detected acoustic Barkhausen signal that results as this zero flux element moves within the material, the signal is isolated as having been generated at a specific depth within the specimen. Since the level of Barkhausen noise varies with stress, a tomographic mapping of stress is obtained for the interior of the ferromagnetic specimen. Through the use of a computer, a three dimensional map of stress in the ferromagnetic material is obtained.