Systematic Abstracts of Current
Selected from literature and from Battelle Technical
Steady-State Behavior of the Dynamic Absorber. J. C. Snowdon. Acoustical Society of America, Journal, v. 31, Aug. 1959, p. rog6-1103. The resonant vibration of machinery and resiliently mounted equipment can be reduced with a dynamic absorber of suitable design. The necessary analytical and graphical information for an optimum design is presented. It is assumed that the absorber mass is attached resiliently to the vibrating item with a rubberlike material, and not with a spring and dashpot in parallel as considered in the classical theory of Ormondroyd and Den Hartog. The dynamic absorber utilizing a material with a stiffness proportional to frequency and a constant damping factor can reduce the resonant vibration of machinery and equipment items considerably. Its performance is superior to that of the classical dynamic absorber.
The Rate of Fatigue-Crack Propagation for Two Aluminum Alloys under Completely Reversed Loading. Walter Illg and Arthur J. McEvily, Jr. NASA Technical Note D-52, October 1959. rgpp., diagrs., photos, tables. OTS price, $0.50. A series of crack propagation tests of sheet specimens has been conducted under completely reversed loading at various stress levels up to 30 k.s.i. Differences between effectsof the compression and tension parts of the cycles are discussed. In both types of loading, the governing parameter was found to be related to the local stress at the crack tip. Investigation of Factors Governing Fatigue Life with the Rolling-Contact Fatigue Spin Rig. T. L. Carter, R. H. Butler, H. R. Bear and W. J. Anderson. ASLE Transactions, v. I, no. I, 1958, p. 23. For abstracts see Wear, v. I, 1957/58, P, 358.
2. ADHESION AND FRICTION Measurements of Heat-Transfer and Friction Coefficients for Helium flowing in a Tube at Surface Temperature-s up to 5900”R. Maynard F. Taylor and Thomas A. Kirchgessner. NASA Technical Note D-133, October ~959. 29 pp. diagrs., photo. OTS price, $0.75. Measurements of average heat-transfer and friction coefficients and local heat-transfer coefficients were made with helium flowing through electrically heated smooth tubes with length-diameter ratios of 60 and 92 for the following range of conditions: average surface temperature from 1457’ to 4533”R, Reynolds number from 3230 to 60,000, heat flux up to 345,000 B.Th.U./h/ft.z of heattransfer area, and exit Mach number to 1.0. In general, the data of this investigation correlated with air data at lower temperatures obtained in previous investigations. Effect of Lubricants on Process of Friction. V. D. Kuznetsov, A. I. Loskutov, and L.M. Kisurina. Henry Brutcher Translation No.
4549. 6 pp. (From Doklady Akademii Nauk S.S.S.R., v. rag, no. I, 1956, p. 124-1~26.) Henry Brutcher, Altadena, Calif. Cases in which surface-active lubricants increase (rather than decrease) the wear of parts in contact, and explanation of this behavior by the chemical interaction between lubricant and solid predominating over other variables. Results of friction tests measured by time to failure of (wire) specimens and weight loss of pulleys in contact with them. Effect of Deformation of the Surface Texture on Rolling Resistance. J. Halling. British Journal of <4pplied I’hysits, v. IO, Apr. 1959, p. 172-176. Describes the results of a series of experiments showing the variation of the coefficient of rolling resistance, 1, with increasing load for hard steel rollers on a variety of steel surfaces. It was found that the initial value of 2,. and the rate of change of ii with increasing load, were both reduced by a series of loading IVPar, 3 (1960) 154