Effect of Viscosity on Rolling-element Fatigue Life at Cryogenic Temperature with Fluorinated Ether Lubricants
National Aeronautics and Space Administration, 1975 - Ethers - 19 pages
Rolling-element fatigue tests were conducted with 12.7-mm-(1/2-in.-) diameter AISI 52100 steel balls in the NASA five-ball fatigue tester, with a maximum hertz stress of 5500 mN/m2 (800 000 psi), a shaft speed of 4750 rpm, lubricant temperature of 200 K (360 R), a contact angle of 20 deg, using four fluorinated ether lubricants of varying viscosities. No statistically significant differences in rolling-element fatigue life occurred using the four viscosity levels. Elastohydrodynamic calculations indicate that values of the lubricant film parameter were approximately 2 or greater.
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52100 steel balls 5500 meganewtons 7-millimeter absolute viscosity angle of 20 ball-lower ball contact bulk lubricant temperature confidence number contact angle cryogenic CRYOGENIC TEMPERATURE decrease in fatigue degree of polymerization Density diameter AISI 52100 EFFECT OF VISCOSITY elastohydrodynamic film thickness equivalent modulus equivalent radius equivalent velocity family of fluorinated fatigue life occurred five-ball fatigue tester fluorinated ether lubricants four different viscosity-level four fluids four lubricants four viscosity levels indicate that values lbf/in liquid nitrogen lives obtained Lubricant designa lubricant film parameter LUBRICANT PROPERTIES Lubricant viscosity LUBRICANTS IN FIVE-BALL m/sec maximum Hertz stress meganewtons per square meter per second mineral oil modulus of elasticity NASA five-ball fatigue outer-race temperature Poisson's ratio profile traces Rolling-element fatigue tests running tracks shaft speed square meter 800 statistically significant differences stress cycles stress of 5500 temperature of 200 test assembly test block upper ball upper ball-lower ball viscosity at bulk