- Email: [email protected]
Stability considerations for a gas-lubricated tilting-pad journal bearing (Part 1: analytical methods)
~STRACT~ Copies of original articles are best oblained by urrihg direct lo the journal in which they appeared. The addresses of journals can be found in a reference book such as ‘World list of sc+enlific and technical publications’, ‘Willings Press guide’, ‘Newspaper press direclory’ and, fpr American journals only) ‘Ayers’.
BABER, B. B., ANDERSON, E. L. and KU, P. M. Effects of lubricants, metals, temperature and atmospheric environments on gear load-carrying capacity. Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 90, Series F, No 1 (January 1968) ~11’7 Experimental gear load-carrying capacity results are presented for three different gear materials and a variety of lubricants of different chemical classes and viscosities, with emphasis on high-temperature operation in air and nitrogen environments. The interaction between lubricant, metal and atmosphere was found to be complex, and could not be predicted by simple means. With a given gear material in an air environment, load-carrying capacity was found to decrease with increasing temperature until a minimum value was reached, and then to increase with further increase in temperature. A substantial reduction in load-carrying capacity was noted when the air environment was replaced with nitrogen. In addition, the increase in load-carrying capacity noted at high temperatures in air environment was not observed when nitrogen environment was used. This general behaviour was, however, quite different when another gear material was used. (Tribology 1968, abstract 47) BURTON, It. A. and STAPH, H. E. Thermally activated seizure of angular contact bearings. Transactions of the American Society of Lubrication Engineers, Vol 10, No 4 (October-December 196’7) ~408 Equations have been developed relating friction-power to bearing element temperatures for the particular case of prelubricated or lightly lubricated ball bearings. An expression is derived for the change in relative dimensions of an angular contact bearing, as determined by the temperature gradient across the bearing. A second expression is found for the accommodation of the bearing to expansion; this accommodation results from elastic deformation and changes in contact angles. A comparison of these relationships reveals that unstable operating conditions may occur and lead to sudden, uncontrollable increases in contact loads. These regions of unstable operation may occur as a result of lubricant degradation or bearing wear, as well as combinations of operating speed and housing dimensions. (Tribology 1968, abstract 48) CHU, T. Y.,McCABE, J. T. and ELROD, 11. G. Stability considerations for a gas-lubricated tilting-pad journal bearing (Part 1: analytical methods). Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 90, Series F, No 1 (January 1968) ~162 The multiplicity of parameters associated with a tilting-pad journal bearing demands that special consideration be given to the selection of an analytical method for stability prediction. The classical frequency response (small perturbation) method and the nonlinear orbit method (a direct numerical integration of all governing differential equations) are discussed and evaluated. A new approach for the determination of film response called the ‘step-jump’ method is here extended to the tilting-pad bearing. Three means of using the film response functions in the dynamical equation are outlined and compared. The relationship of the frequency response method to the step-jump method is explained and a comparison of the step-jump results with the nonlinear orbit approach is made. One of the techniques for applying the step-jump response functions, called the ‘characteristic equation’ method, is shown to be most suitable for parametric studies of stability thresholds. (Tribology 1968, abstract 49)
CUELLAR, J. P. and BABER, B. B. Oxidation-corrosion characteristics of aircraft turbine engine lubricants. Transactions of the American Society of Lubrication Engineers, Vol 10, No 4 (OctoberDecember 1967) ~363 Apparatus and test procedure are described for the evaluation of the oxidation-corrosion characteristics of synthetic lubricants at elevated temperatures. An 18hr test was used, and screening test data are presented for eight lubricants covering a temperature range of 220-300”F, where lubricant capability permitted. The effects of moist test air and varying temperature are demonstrated for several MIL-L-9236 type and experimental type lubricants in the 18hr test. Results are also given for a 5P4E polyphenyl ether using varied test conditions of temperature, metal specimens, air flow, nitrogen-air mixtures, and reflux of condensable vapours. Similar but less extensive studies are described for several other oil formations. (Tribology 1968, abstract 50)
CZASTKA, N. F. A novel type of bearing bushes provided with a thin metallic-graphite coat. VDI Zeitschrift, Vol 110, No ‘7 (March 1968) ~279 These bearing bushes, designed in Czechoslovakia, consist of a steel strip with a prime coat of a porous sinter metal, which has been sintered on the strip, and a gliding deck coat of 2mm thickness of lead bronze and graphite. The gliding deck coat is rolled on the prime coat. (Tribology 1968, abstract 51)
DORINSON, A. Primary modes and observable phenomena in the mechanical wear of metals. Wear,Vol ll,No 1 (January 1968) ~29’ Four preliminary wear mechanisms may be induced from the behaviour of moving surfaces under load: (a) the adhesive mechanism; (b) the plastic deformation mechanisms; (c) the spalling or pitting mechanism; (d) the chemical or corrosive mechanism. The recognition is described of the action of these mechanisms on examination of worn surfaces from well-controlled experiments with a pin and disc apparatus. The’ difficulty of identifying the determinative mechanism for destructive wear by inspection-of badly damaged parts is discussed. (Tribology 1968, abstract 52)
D’YAKOVA, A. G. Wear of bell bearings working in water without lubrication. Vestnik Mashinostroeniya, No 1 (January 1968) ~35 Results are reported of experiments on the nature of wear occurring in bearings working in water and of the factors limiting the life of such bearings. (Tribology 1968, abstract 53)
ELKONIN, B. V. Performance of ball bearing cages at low temperatures. Vestnik Mashinostroeniya, NO 1 (January 1968) ~34 Comparative evaluation is given of wear in cages made of PTFE 4 and PTFE 3. The possibility is noted of using PTFE 3 as a constructional material for ball bearing cages intended for low-temperature work. (Trlbology 1968, abstract 54) TRIBOLOGY
March
1968
123
BABER, B. B., ANDERSON, E. L. and KU, P. M. Effects of lubricants, metals, temperature and atmospheric environments on gear load-carrying capacity. Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 90, Series F, No 1 (January 1968) ~11’7 Experimental gear load-carrying capacity results are presented for three different gear materials and a variety of lubricants of different chemical classes and viscosities, with emphasis on high-temperature operation in air and nitrogen environments. The interaction between lubricant, metal and atmosphere was found to be complex, and could not be predicted by simple means. With a given gear material in an air environment, load-carrying capacity was found to decrease with increasing temperature until a minimum value was reached, and then to increase with further increase in temperature. A substantial reduction in load-carrying capacity was noted when the air environment was replaced with nitrogen. In addition, the increase in load-carrying capacity noted at high temperatures in air environment was not observed when nitrogen environment was used. This general behaviour was, however, quite different when another gear material was used. (Tribology 1968, abstract 47) BURTON, It. A. and STAPH, H. E. Thermally activated seizure of angular contact bearings. Transactions of the American Society of Lubrication Engineers, Vol 10, No 4 (October-December 196’7) ~408 Equations have been developed relating friction-power to bearing element temperatures for the particular case of prelubricated or lightly lubricated ball bearings. An expression is derived for the change in relative dimensions of an angular contact bearing, as determined by the temperature gradient across the bearing. A second expression is found for the accommodation of the bearing to expansion; this accommodation results from elastic deformation and changes in contact angles. A comparison of these relationships reveals that unstable operating conditions may occur and lead to sudden, uncontrollable increases in contact loads. These regions of unstable operation may occur as a result of lubricant degradation or bearing wear, as well as combinations of operating speed and housing dimensions. (Tribology 1968, abstract 48) CHU, T. Y.,McCABE, J. T. and ELROD, 11. G. Stability considerations for a gas-lubricated tilting-pad journal bearing (Part 1: analytical methods). Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 90, Series F, No 1 (January 1968) ~162 The multiplicity of parameters associated with a tilting-pad journal bearing demands that special consideration be given to the selection of an analytical method for stability prediction. The classical frequency response (small perturbation) method and the nonlinear orbit method (a direct numerical integration of all governing differential equations) are discussed and evaluated. A new approach for the determination of film response called the ‘step-jump’ method is here extended to the tilting-pad bearing. Three means of using the film response functions in the dynamical equation are outlined and compared. The relationship of the frequency response method to the step-jump method is explained and a comparison of the step-jump results with the nonlinear orbit approach is made. One of the techniques for applying the step-jump response functions, called the ‘characteristic equation’ method, is shown to be most suitable for parametric studies of stability thresholds. (Tribology 1968, abstract 49)
CUELLAR, J. P. and BABER, B. B. Oxidation-corrosion characteristics of aircraft turbine engine lubricants. Transactions of the American Society of Lubrication Engineers, Vol 10, No 4 (OctoberDecember 1967) ~363 Apparatus and test procedure are described for the evaluation of the oxidation-corrosion characteristics of synthetic lubricants at elevated temperatures. An 18hr test was used, and screening test data are presented for eight lubricants covering a temperature range of 220-300”F, where lubricant capability permitted. The effects of moist test air and varying temperature are demonstrated for several MIL-L-9236 type and experimental type lubricants in the 18hr test. Results are also given for a 5P4E polyphenyl ether using varied test conditions of temperature, metal specimens, air flow, nitrogen-air mixtures, and reflux of condensable vapours. Similar but less extensive studies are described for several other oil formations. (Tribology 1968, abstract 50)
CZASTKA, N. F. A novel type of bearing bushes provided with a thin metallic-graphite coat. VDI Zeitschrift, Vol 110, No ‘7 (March 1968) ~279 These bearing bushes, designed in Czechoslovakia, consist of a steel strip with a prime coat of a porous sinter metal, which has been sintered on the strip, and a gliding deck coat of 2mm thickness of lead bronze and graphite. The gliding deck coat is rolled on the prime coat. (Tribology 1968, abstract 51)
DORINSON, A. Primary modes and observable phenomena in the mechanical wear of metals. Wear,Vol ll,No 1 (January 1968) ~29’ Four preliminary wear mechanisms may be induced from the behaviour of moving surfaces under load: (a) the adhesive mechanism; (b) the plastic deformation mechanisms; (c) the spalling or pitting mechanism; (d) the chemical or corrosive mechanism. The recognition is described of the action of these mechanisms on examination of worn surfaces from well-controlled experiments with a pin and disc apparatus. The’ difficulty of identifying the determinative mechanism for destructive wear by inspection-of badly damaged parts is discussed. (Tribology 1968, abstract 52)
D’YAKOVA, A. G. Wear of bell bearings working in water without lubrication. Vestnik Mashinostroeniya, No 1 (January 1968) ~35 Results are reported of experiments on the nature of wear occurring in bearings working in water and of the factors limiting the life of such bearings. (Tribology 1968, abstract 53)
ELKONIN, B. V. Performance of ball bearing cages at low temperatures. Vestnik Mashinostroeniya, NO 1 (January 1968) ~34 Comparative evaluation is given of wear in cages made of PTFE 4 and PTFE 3. The possibility is noted of using PTFE 3 as a constructional material for ball bearing cages intended for low-temperature work. (Trlbology 1968, abstract 54) TRIBOLOGY
March
1968
123