Hydrodynamic Aspects of Fatigue in Plain Journal Bearings

Abstract

The fatigue resistance of different bearing materials is usually given an “order of merit” in terms of specific load on the bearing. The bearing material cannot directly sense the applied specific load, since it is the hydrodynamic oil film pressures which directly create the stresses in the lining; both pressures and stresses need to be examined to see if a more meaningful criterion for fatigue can be found. As a first step in this study the experimental fatigue work carried out by Gyde at the University of Denmark was examined and compared with trends in peak specific load, hydrodynamic characteristics, and bearing lining stresses. It has been shown that peak specific load and peak hydrodynamic pressure are not in themselves realistic parameters, but that pressure variation on a bearing element, perhaps including some rapidly forming negative pressures, could be a significant term. The study of the more fundamental material stresses has not yet been extended to allow for the influence of any nonpositive film pressures, but results so far follow similar trends to those obtained on the pressure variation criterion.

Experimental Study on Mechanical Characteristics of PTFE Material

“…More recently, PTFE coatings are being applied in dynamically loaded bearings such as connecting rod big end and crankshaft bearings in automobiles to reduce wear during stop and go stages of automobile driving cycle. However, dynamically loaded bearings pose new challenge to the bearing designer in the form of fatigue damages [4]. Failure of materials due to fatigue damages is statistical in nature.…”

Multiaxial life prediction of hydrodynamic plain bearings

“…A wide used parameter for journal bearing design is the specific load p spec , which is the applied load divided by the projected bearing area. This parameter was refused by other authors in the past upon good reason [1,2]. In a dynamically loaded bearing, not the specific load is a parameter for assessing fatigue but rather the multiaxial and often non-proportional stress quantities, induced by the oil film pressure into the lining material.…”

Problems of Analytical Determination of Journal Bearing Bush Fatigue Strength Estimates

“…Fatigue failures in lining of bearing bushes are one of the forms of destructive damages in technical devices in which cyclic loadings occur. The fatigue phenomena begin at surface cracks axially oriented, which is generally explained as the effect of tangential stresses [1,2]. The magnitudes of load leading to bearing fatigue for a given load pattern can only be determined experimentally whereas the estimate of corresponding critical stress may be evaluated analytically [3].…”