MEASUREMENT

Award Information
Agency: Department of Defense
Branch: Army
Contract: N/A
Agency Tracking Number: 925
Amount: $50,000.00
Phase: Phase I
Program: SBIR
Awards Year: 1984
Solitcitation Year: N/A
Solitcitation Topic Code: N/A
Solitcitation Number: N/A
Small Business Information
Dominion Engineering, Inc.
6862 Elm Street, Mclean, VA, 22101
Duns: N/A
Hubzone Owned: N
Woman Owned: N
Socially and Economically Disadvantaged: N
Principal Investigator
 DR. ARTHUR P. L. TURNER
 (703) 790-5544
Business Contact
Phone: () -
Research Institution
N/A
Abstract
AT PRESENT IT IS DIFFICULT TO DETERMINE THE AXIAL LOAD IN A BOLTED CONNECTION. TORQUE MEASUREMENTS ARE UNRELIABLLE DUE TO VARIABLE FRICTION COEFFICIENTS AND OTHER MORE ACCURATE METHODS SUCH AS HYDRAULIC TENSIONERS, ULTRASONIC MEASUREMENTS, STRAIN GAUGES, AND X-RAY DIFFRACTION ARE OFTEN IMPRATICAL IN THE FIELD. THE PURPOSE OF THIS PROPOSAL IS TO DEMONSTRATE THAT BOLT AXIAL STRESSES, AND THEREFORE LOADS, CAN BE DETERMINED RELIABLY IN THE FIELD USING THE MAGNETOELASTIC PROPERTIES OF FERROMAGNETIC MATERIAL. WHEN A FERROMAGNETIC MATERIAL, SUCH AS A STEEL BOLT, IS SUBJECTED TO A MAGNETIZING FIELD A SERIES OF ABRUPT CHANGES IN MATERIAL MAGNETIZATIONOCCURS. THIS PHENOMENON IS KNOWN AS "BARKHAUSEN NOISE." PREVIOUS TESTS HAVE CONFIRMED THAT THE BARKHAUSEN NOISE LEVEL IS PROPORTIONAL TO THE STRESS LEVEL IN THE MATERIAL WHICH IS BEING SUBJECTED TO THE MAGNETIXZING FIELD. SMALL, PORTABLE EQUIPMENT IS COMMERCIALLY AVAILABLE WHICH USES THE BARKHAUSEN PRINCPLE TO DETERMINE THE RESIDUAL STRESSES IN WELD SEAMS, FORGINGS, CASTINGS, SHAFTS AND CAMS, ETC. THIS PROPOSAL IS TO MODIFY THIS COMMERCIALLY AVAILABL EQUIPMENT TO MEET THE NEED TO BOLT STRESS MEASUREMENT AND THEN TO DEMONSTRATE THAT BOLT AXIAL STRESSES AND HENCE BOLT AXIAL LOADS, CAN BE CORRELATED TO THE BARKHAUSEN NOISE LEVEL MEASURED ON THE BOLT HEAD OR IN A SMALL DIAMETER HOLE IN THE BOLT SHANK.

* information listed above is at the time of submission.

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