DocumentCode :
1461235
Title :
Experiments to measure gouging threshold velocity for various metals against copper
Author :
Stefani, Francis ; Parker, Jerald V.
Author_Institution :
Inst. for Adv. Technol., Texas Univ., Austin, TX, USA
Volume :
35
Issue :
1
fYear :
1999
fDate :
1/1/1999 12:00:00 AM
Firstpage :
312
Lastpage :
316
Abstract :
Hypervelocity gouging is a form of damage that can occur to surfaces in sliding contact at high relative velocity. Gouges, which are in the form of teardrop-shaped craters, have been observed on rocket sled tracks, in light gas gun barrels, and in the bore of railguns. One aspect of gouging that has not been adequately explained is the existence of a minimum velocity (or threshold velocity) for a given material pair below which gouging does not occur. This paper reports a series of experiments to test the hypothesis that the onset of gouging is governed by the hardness of the harder material and by the density and sound speed of both materials. In the tests, samples of various metals were accelerated to 2.2 km/s while in direct sliding contact with CD110 copper rails. The samples were carried in a Lexan polycarbonate forebody, modified to apply normal loads of 40-80 MPa to the sample/rail interface. The portion of the armature directly in line with the samples was cut away to avoid contaminating the gouge track. Visual inspection of the resulting gouges was used to establish a gouging threshold for each metal. The tests were conducted in the 40 mm square bore electromagnetic launcher at the Institute for Advanced Technology (IAT). Metals tested include AISI 1015 steel, silver, molybdenum, pure copper, tungsten, nickel, magnesium, and 7075 aluminum alloy. The results of the experiments show the existence of a straight line fit between hardness of the harder material and the shock pressure for a normal collision at the gouging threshold velocity
Keywords :
copper; electrical contacts; hardness; railguns; velocity measurement; 2.2 km/s; 40 mm; 40 to 80 MPa; 7075 aluminum alloy; AISI 1015 steel; Ag; CD110 copper rails; Cu; Institute for Advanced Technology; Lexan polycarbonate forebody; Mg; Mo; Ni; W; direct sliding contact; gas gun barrels; gouging threshold velocity; high relative velocity; hypervelocity gouging; magnesium; material density; material hardness; material sound speed; minimum velocity; molybdenum; nickel; normal collision; pure copper; railgun bores; rocket sled tracks; sample/rail interface; shock pressure; silver; sliding contact; square bore electromagnetic launcher; teardrop-shaped craters; threshold velocity; tungsten; visual inspection; Acoustic materials; Aerospace materials; Boring; Copper; Pollution measurement; Railguns; Rails; Rockets; Testing; Velocity measurement;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/20.738423
Filename :
738423
Link To Document :
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