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:
Mar. 11, 1997
Filed:
Jun. 07, 1995
Yu P Ma, Nashville, TN (US);
John P Wikswo, Jr, Brentwood, TN (US);
Vanderbilt University, Nashville, TN (US);
Abstract
A sheet inducer carrying a uniformly distributed ac current induces a sheet eddy current generally parallel to a generally smooth surface of an electrically conductive object. A magnetometer, preferably a superconducting quantum interference device (SQUID) magnetometer, detects the component of a magnetic field generally perpendicular to the generally smooth surface resulting from disturbances in the sheet eddy current caused by a flaw. Through appropriate selection of the phase angle between the detector signal and the applied current, the response can be adjusted to suppress surface flaws and enhance detection of flaws below the surface. The sheet eddy current is induced in multiple directions to detect flaws of all orientations and at multiple frequencies to refine determination of the size, shape, and depth of a flaw. An elongated solenoid is used to induce a circumferential sheet eddy current in elongated objects such as tubes and rods, and a current-carrying rod is used to induce a longitudinal sheet eddy current in an elongated tubular object.