Pressure measurements of nonplanar stress waves

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6359686

Carlson, G H; Charest, J A

Measuring the pressure of non-planar stress waves using thin piezo-resistive gages requires correcting for induced strain parallel to the sensing elements. A technique has been developed that permits such measurements, making use of a dual element gage. One element, Manganin, is sensitive to stress both parallel and perpendicular to the sensing element; the other element, Constantan, is primarily sensitive to stress parallel to the sensing element. The change in resistance in the Constantan element is thereby used to correct for the strain effect parallel to the Manganin element axis. Individual and combined Manganin and Constantan elements were subjected to controlled gas gun impact tests in the pressure and strain ranges of 0 to 50 kbar and 0 to 7%, respectively. From planar wave tests, the piezoresistivity of Constantan was found to be positive but negligible in comparison with Manganin. From combined stress and strain environments, the compression and tension strain factors of Constantan were found to be constant and equal to 2.06. The strain factors of Manganin were found to increase from 1.2 to 2.0 asymptotically in the range of 0 to 3% strain. It was experimentally demonstrated that, because of the closeness of their strain factors, the Manganin-Constantan dual element gage could be used in the differential recording mode to yield pressure directly. In this mode the gage is a strain compensating gage. Analytical techniques have also been developed for more accurate strain compensation.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6359686
• Report Number(s): LA-UR-81-2343; CONF-810931-1; ON: DE81028729
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420200* -- Engineering-- Facilities
Equipment
& Techniques
440300 -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
ALLOYS
CONSTANTAN
COPPER ALLOYS
COPPER BASE ALLOYS
DESIGN
DYNAMIC LOADS
IMPACT SHOCK
MANGANESE ALLOYS
MANGANIN
MEASURING INSTRUMENTS
MECHANICAL STRUCTURES
NICKEL ALLOYS
PENETROMETERS
PERFORMANCE
PIEZOMETRY
PRESSURE GAGES
PRESSURE MEASUREMENT
PROJECTILES
SHOCK WAVES
STRAIN GAGES
STRESSES
WAVE PROPAGATION