Contact fatigue initiation and tensile surface stresses at a point asperity which passes an elastohydrodynamic contact

Abstract

Contact mechanics and tribology was combined with fundamental fatigue and fracture mechanics to form a new mechanism for surface initiated rolling contact fatigue. Following, fatigue was investigated numerically for single asperities and craters in lubricated rolling contact surfaces. The hypothesis suggests that asperity point contacts can create sufficiently large tensile stresses for fatigue. The investigated case corresponded to a heavily loaded truck gear with ground surfaces. Reynolds equation resolved the elastohydrodynamic effect of the asperity in the transient three dimensional contacts. The Findley critical plane criterion was used for multiaxial and non-proportional fatigue evaluation. The simulations confirmed the new mechanism for rolling contact fatigue and showed how asperities can create contact fatigue in the lubricated contacts even without slip.

Development of accelerated comparative assessment of contact fatigue strength based on the analysis of acoustic emission of friction units

“…The amount of energy W cr * essentially determines the fatigue strength of the surface layer of the material. 10,30–32 In these works, it is noted that the function describing the kinetics of damage development f ( n ) significantly depends on the rate of external influence v i .…”

Investigation of the asperity point load mechanism for thermal elastohydrodynamic conditions

“…Cavitation was treated by forcing p  0. The asperity shape was modelled with an axisymmetric cosine profile; see Everitt and Alfredsson [4]. The pressure-viscosity relation of the lubricant was described by Roelands' equation:…”

“…where amp is the shear stress amplitude on a plane and n,max is the maximum normal stress on the same plane.  F = 0.627 and  eF = 625 MPa are the normal stress parameter and the endurance limit for the current case carburized gear steel [4]. The plane that maximizes Fi is searched for.…”

Statistical analysis on rolling contact fatigue in railroad axle bearing steel

“…A typical crack is shown in Figure 9, where a is the angle between the direction of the frictional force and the crack and l is the length of the crack. The maximum half-width r for two elastic bodies in linear contact is given by the following equation 40,41 :…”