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:
Feb. 12, 2002
Filed:
Jun. 30, 2000
Seiki Takahashi, Iwate Pref., JP;
Iwate University, Iwate Pref., JP;
Abstract
A nondestructive test method determines fatigue of a test ferromagnetic construction material by quantifying a change in effective stress due to aging of the test material, in which the magnetic susceptibility (&khgr; ) of the test material is measured in its aged state under a magnetic field having a specified intensity (H) according to a relation as expressed by a first equation: c=&khgr; H . The magnetic susceptibility (&khgr; ) so measured and the magnetic field intensity (H) are put into the first equation, to obtain a susceptibility coefficient (c) of the test material. The susceptibility coefficient (c) so obtained is put into a second equation: &sgr;={log (c)−a}/b, where a and b are known constants determined by an internal structure of the test material, to obtain a current tensile stress (&sgr;) of the test material. The current tensile stress (&sgr;) of the test material so obtained is compared with a known, initial tensile stress (&sgr; ) of the same test material, to determine a change in effective tensile stress of the test material.