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:
Jun. 07, 1994
Filed:
Mar. 18, 1991
Hitachi, Ltd., Tokyo, JP;
Abstract
A corrosive environmental crack length measuring apparatus including a double-cantilever beam type test piece having a tapered portion in a portion where the crack grows, a slit, and at least two holes, with the test piece being placed within a corrosive environment. Leads inserted in the holes of the test piece to be spot-welded thereto to supply a direct current to the holes. A current polarity switching device is provided with, a stabilized direct current power supply connected with the direct current supplying leads through the current polarity switching device. Potential difference measuring leads are inserted in holes formed in two outer faces of the double-cantilever beam type test piece parallel to a section of a crack growing portion at a plurality of points along the crack growing direction so as to be spot-welded thereto. A multiplexer is provided with, a micro-voltmeter connected with the potential difference measuring leads through the multiplexer, and an arithmetic unit judges crack length based on ratios between potential differences measured by switching the polarity of direct current using the current polarity switching device.