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. 06, 2001
Filed:
Mar. 23, 1999
Alfred V. Clark, Boulder, CO (US);
George Alers, Boulder, CO (US);
Thanh Nguyen, Roanoke, VA (US);
Christopher Hehman, Raleigh, NC (US);
Kevin Coakley, Boulder, CO (US);
The United States of America as represented by the Secretary of Commerce, Washington, DC (US);
Abstract
A method for measurement of stress in a specimen utilizing a motorized electromagnetic acoustic transducer (EMAT). Stress causes a rotation of the pure-mode polarization directions of SH-waves and a change in the phase of waves polarized along these certain directions. The method utilizes a rotating small-aperture EMAT, connected to a processor, to measure phase and amplitude data as a function of angle. The EMAT is placed on a workpiece at the location where the stress is to be measured. The acoustic birefringence B is determined from the normalized difference of these phases. From these data, an algorithm calculates values of B. and &phgr;. The workpiece is then stressed or its stress state is changed. The values are measured again at the same location. Stress is determined from the change in B and &phgr;.