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:
Sep. 26, 1978
Filed:
Jun. 10, 1977
Lynn Marshall Barker, Salt Lake City, UT (US);
Terra Tek, Inc., Salt Lake City, UT (US);
Abstract
The present invention consists of a method for accurately measuring the plane strain fracture toughness of ductile and brittle materials, the method to be practiced on a specimen formed such that, when the specimen is appropriately loaded, a crack will initiate at a predetermined point or line, with such crack formed thereat being intrinsically stable such that the load executed on the specimen must be continually increased in order to further advance the crack along a predetermined path through the specimen, until, at some critical location along the predetermined crack path, the load necessary to further advance the crack reaches a maximum, thereafter decrasing as the crack advances beyond the critical location along the remainder of its predetermined path through the specimen, that critical location being essentially independent of the specimen material, it being determined by the specimen geometry alone as long as elastic plane strain conditions prevail in the specimen sufficiently close to the crack tip. The method of the present invention involves taking the specimen through an appropriate loading sequence and determining the critical (or maximum) load that occurs when the crack passes through the critical position. With that data, the plane strain critical stress intensity factor, K.sub.IC, or fracture toughness for the specimen material, can be calculated mathematically considering the critical load, the specimen size and geometry, taking into account the Poisson's ratio of the specimen material, but without necessitating reference to any other standard specimen or fracture toughness test results thereon.