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Effect of lubricant viscosity and type on ball fatigue life
VOL. 2 PWW)
SY’STEMATIC ABSTRACTS
characteristic striations first observed by Zapffe and Worden are each associated with a single cycle of stress. Quantitative microscopy on the fractures of a series of Rolls Royce fatigue specimens showed the mean spacing of the striations to be increased by increase of fatigue stress. The second part of the paper deals with the examination of a fracture from a programmed fatigue test on a large bolted joint. From measurements of the distance between progression markings, the crack propagation rates in two fatigue areas were plotted. The results demonstrated that cracks were propagating in this specimen very early in its fatigue life. It is thought that the early propagation of cracks in this specimen was due to the severe fretting damage that occurred during the test. Some Corrosion Fatigue Observations on High Purity Aluminum-Zinc-Magnesium Alloy and CommercialDTD 683. C. A. Stubbington and P. J. E. Forsyth. Royal Aircraft Establishment (Gt. Brit.) May 1958. 15 pp., diagrs., photo’s, tabs. (Ask for N-66304) Rolls Royce rotating cantilever air and corrosion fatigue tests have been made on the above materials which have been aged for various times. These results are compared with special reference to the form of fracture and microstructure. A mechanism for corrosion fatigue in these alloys is discussed. Effect of Lubricant Viscosity and Type on Bali Fatigue Life. William J. Anderson and Thomas L. Carter. ASLE Transactions, v. I, no. 2, Oct. 1958, p. 266-272.
491
Four paraffinic mineral oils with viscosities of 5 to 113 centistokes at the 100°F test temperature were used. Longer life was obtained with more viscous oil, life varying approximately as the 0.2 power of lubricant viscosity. In investigation of methyl silicone, a paraffinic mineral oil, a sebacate, a water base glycol, and an adipate were used. Each had a viscosity of about IO centistokes at the IOO’F test temperature. The 10% life was about 40 times as great with the silicone as with the adipate. Fatigue of a Nut and Bolt. P. B. Walker. Royal Aircraft Establishment (Gt. Brit.) June 1958. 22 pp., diagrs. RAE Structures 238. (Ask for N-66130) The factors that adversely affect the fatigue life of a tension bolt are analysed. The aim is to produce a comprehensive picture, derived as far as possible from fundamental principles and showing the various factors in relation to each other. Both external loading and the internal stress pattern are considered. The effects of plastic deformation and of controlled pretensioning are also brought into the genera1 picture as complicating factors, though usually beneficial. Improve Fatigue Strength With Abrasive Tumbling. Iron Age, v. 183, no. 8, Feb. rg, 1959, p. r29131.
Sponsored by the Abrasive Grain Association, the test program proves the usefulness of tumbling in attaining better fatigue strength.
2. FRICTION
The Viscosity Wedge. A. Cameron. ASLE Transactions,
v. I, no. 2,
Oct. 1958, p. 248-253.
Equations are set up and solved numerically giving coefficients for oil film thickness and friction. Thickness is comparable (three quarters) of that carried by Michell pads. Computed results are applied to a parallei surface thrust bearing described by Fogg and shown to give tolerable agreement with experimental findings. Plane Sliders of Finite Width. Donald F. Hays. ASLE Transactions, v. I, no. 2, Oct. 1958, p. 233-240. Illustratesthe manner by which the separation of variables in Reynolds’ equation may be effected, completes the solution of the resulting eigenvalue problem, and shows the formulation of the expressions for load capacity, frictional resistance, center of pressure,
coefficient of friction, and rates of flow. Typical pressure hills are shown as well as approximate flow patterns throughout the slider area. 2.2. Tire-to-surface
Reibung von Gummi. Friction of Rubber. Eric Gough. Ka~tsc~~k zmd Gum&, v. II, Nov. IQ+, p. WT3o3-WT3x2. Reasons for using rubber in structural elements and power transmission. Frictional properties. Skidding at low speeds. The use of belts and disks. Transmission of traction and brake pressure through tires. Cornering. Friction laws. Comparison between rubber and metal friction. Tire-to-Surface Friction especially under Wet Conditions. Richard H. Sawyer, Sidney A. Batterson, and Eziaslav N. Harrin. NASA Menzorandum z-
SY’STEMATIC ABSTRACTS
characteristic striations first observed by Zapffe and Worden are each associated with a single cycle of stress. Quantitative microscopy on the fractures of a series of Rolls Royce fatigue specimens showed the mean spacing of the striations to be increased by increase of fatigue stress. The second part of the paper deals with the examination of a fracture from a programmed fatigue test on a large bolted joint. From measurements of the distance between progression markings, the crack propagation rates in two fatigue areas were plotted. The results demonstrated that cracks were propagating in this specimen very early in its fatigue life. It is thought that the early propagation of cracks in this specimen was due to the severe fretting damage that occurred during the test. Some Corrosion Fatigue Observations on High Purity Aluminum-Zinc-Magnesium Alloy and CommercialDTD 683. C. A. Stubbington and P. J. E. Forsyth. Royal Aircraft Establishment (Gt. Brit.) May 1958. 15 pp., diagrs., photo’s, tabs. (Ask for N-66304) Rolls Royce rotating cantilever air and corrosion fatigue tests have been made on the above materials which have been aged for various times. These results are compared with special reference to the form of fracture and microstructure. A mechanism for corrosion fatigue in these alloys is discussed. Effect of Lubricant Viscosity and Type on Bali Fatigue Life. William J. Anderson and Thomas L. Carter. ASLE Transactions, v. I, no. 2, Oct. 1958, p. 266-272.
491
Four paraffinic mineral oils with viscosities of 5 to 113 centistokes at the 100°F test temperature were used. Longer life was obtained with more viscous oil, life varying approximately as the 0.2 power of lubricant viscosity. In investigation of methyl silicone, a paraffinic mineral oil, a sebacate, a water base glycol, and an adipate were used. Each had a viscosity of about IO centistokes at the IOO’F test temperature. The 10% life was about 40 times as great with the silicone as with the adipate. Fatigue of a Nut and Bolt. P. B. Walker. Royal Aircraft Establishment (Gt. Brit.) June 1958. 22 pp., diagrs. RAE Structures 238. (Ask for N-66130) The factors that adversely affect the fatigue life of a tension bolt are analysed. The aim is to produce a comprehensive picture, derived as far as possible from fundamental principles and showing the various factors in relation to each other. Both external loading and the internal stress pattern are considered. The effects of plastic deformation and of controlled pretensioning are also brought into the genera1 picture as complicating factors, though usually beneficial. Improve Fatigue Strength With Abrasive Tumbling. Iron Age, v. 183, no. 8, Feb. rg, 1959, p. r29131.
Sponsored by the Abrasive Grain Association, the test program proves the usefulness of tumbling in attaining better fatigue strength.
2. FRICTION
The Viscosity Wedge. A. Cameron. ASLE Transactions,
v. I, no. 2,
Oct. 1958, p. 248-253.
Equations are set up and solved numerically giving coefficients for oil film thickness and friction. Thickness is comparable (three quarters) of that carried by Michell pads. Computed results are applied to a parallei surface thrust bearing described by Fogg and shown to give tolerable agreement with experimental findings. Plane Sliders of Finite Width. Donald F. Hays. ASLE Transactions, v. I, no. 2, Oct. 1958, p. 233-240. Illustratesthe manner by which the separation of variables in Reynolds’ equation may be effected, completes the solution of the resulting eigenvalue problem, and shows the formulation of the expressions for load capacity, frictional resistance, center of pressure,
coefficient of friction, and rates of flow. Typical pressure hills are shown as well as approximate flow patterns throughout the slider area. 2.2. Tire-to-surface
Reibung von Gummi. Friction of Rubber. Eric Gough. Ka~tsc~~k zmd Gum&, v. II, Nov. IQ+, p. WT3o3-WT3x2. Reasons for using rubber in structural elements and power transmission. Frictional properties. Skidding at low speeds. The use of belts and disks. Transmission of traction and brake pressure through tires. Cornering. Friction laws. Comparison between rubber and metal friction. Tire-to-Surface Friction especially under Wet Conditions. Richard H. Sawyer, Sidney A. Batterson, and Eziaslav N. Harrin. NASA Menzorandum z-