[Federal Register Volume 59, Number 24 (Friday, February 4, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-2528]


[[Page Unknown]]

[Federal Register: February 4, 1994]


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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

[Notice 94-006]

 

Invention Available for Licensing

AGENCY: National Aeronautics and Space Administration.

ACTION: Notice of availability for licensing.

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SUMMARY: The invention listed below is owned by an agency of the U.S. 
Government and is available for licensing in the U.S. in accordance 
with 35 U.S.C. 207 to achieve expeditious commercialization of results 
of federally funded research and development.
    U.S. Patent Application Number 08/129,294, filed September 24, 
1993, and entitled ``Ultrasonic Dynamic Vector Stress Measurement 
Method and Sensor''--The present invention relates in general to 
dynamic stress measurement when a material is put under a load and more 
particularly to a method and apparatus for measuring changes in stress 
via a pulsed phase locked loop technique.
    A stress measurement method and sensor according to the invention 
consists of directly and dynamically measuring stress changes at the 
location touched by a probe device when a material or structure is 
placed under a load. Electronics employing a pulsed phase locked loop 
(P2L2) technology are coupled to a probe system which is placed in 
contact with a material under stress. A gated signal from the voltage 
controlled oscillator (VCO), a free running oscillator on all the time, 
drives the transducer exciter at the transmitter and causes an acoustic 
wave to be propagated across a sample under stress. The VCO also sends 
a reference signal to the mixer. The output of the mixer represents the 
phase difference of the reference and propagated signals and serves as 
a feedback signal to the VCO. This phase difference tracks the changes 
in stress in the sample. The P2L2 reacts to the change in stress by 
changing its operating frequency according to a specified relationship. 
The AC component of the feedback signal represents the change in 
voltage needed to keep the system in quadrature to follow the change in 
stress. This signal is extracted for amplitude calibration. Calibration 
is accomplished by placing the probe on a plate of similar propagation 
factors and a known cyclic change in applied stress. The resulting AC 
signal multiplied by a calibration factor is equal to the stress.
    The invention claimed in this patent application is available for 
licensing on an exclusive, partially exclusive or nonexclusive basis 
for upfront, running and annual minimum royalty payments to a partner 
committed to commercializing this technology.

ADDRESSES: Licensing information and a copy of the U.S. Patent 
Application (without the claims) may be obtained by writing to Kimberly 
A. Chasteen at the Office of Patent Counsel, Mail Stop 143, NASA 
Langley Research Center, Hampton, VA 23681-0001 (telephone (804) 864-
3227, fax (804) 864-8298). Please note the case number, LAR-14,433-1, 
when requesting information.

    Dated: January 28, 1994.
Edward A. Frankle,
General Counsel.
[FR Doc. 94-2528 Filed 2-3-94; 8:45 am]
BILLING CODE 7510-01-M