Effects of material heterogeneity on surface fatigue for rough lubricated rolling–sliding contacts

Abstract

In view of increasingly severe operating conditions and the use of composite (strongly) heterogeneous materials, detailed modelling and optimisation methods are needed to predict the effects of subsurface material topology, either by design or resulting from inclusions and material anisotropy, on rolling-sliding contact fatigue life. In this paper, a method is proposed showing that such predictions can at present be obtained for realistic configurations on small-scale computers by integrating efficient numerical solution of the 3D displacement and stress field in the (heterogeneous) material with fast rough surface-lubricated contact models. Contact pressures, subsurface stresses and surface fatigue effects are shown for cases of bonded individual or multiple (clusters) of statistically distributed inhomogeneities close to the surface in realistic actual rolling–sliding rough contact geometries. The model contributes to the development of optimised failure criteria for composite/heterogeneous materials close to the surface.

Theoretical analysis of a rolling-sliding elastohydrodynamic lubrication line contact with a subsurface inclusion

“…The existence of a strong feedback process between the effects of the inclusion and the lubricant's response affecting the von Mises stresses is also highlighted. Furthermore, the numerical results are directly compared with predictions by the semi-analytical model proposed in Morales-Espejel et al., 24 obtaining a reasonable qualitative agreement. However, quantitatively some differences are observed.…”

“…First, to investigate by means of full EHL numerical simulations the time-dependent evolution of film thickness and pressure perturbations introduced by moving subsurface inclusions. Second, to verify the rapid, semi-analytical model 24 predictions by direct comparison with full numerical simulations. For the sake of simplicity but without loss of generality, the analysis is limited to a single cylindrical inclusion of varying stiffness in a line contact configuration.…”

“…However, the time dependent evolution of pressure and film perturbations caused by the inclusions is not investigated. In this regard, Morales-Espejel 22 combined the rapid, semi-analytical micro-EHL model 6,8 with Eshelby's equivalent inclusion method 23 and, subsequently, 24 with the more efficient, finite-difference multigrid method for heterogeneous materials of Boffy et al 25,26 This enabled efficient solution of the problem in order to study the influence of inclusions on the EHL pressures, film thickness, and stresses. Time-dependent series of results are presented using single, multiple equidistant, or random ellipsoidal inclusions under rolling-sliding conditions, both for the cases where the surfaces are either smooth or including waviness.…”

Multigrid solution of 2D and 3D stress fields in contact mechanics of anisotropic inhomogeneous materials

“…The determination of criticality criteria for local material variations/inclusions, and computational diagnostics based on tomographic images. Finally, the developed method can relatively easily be coupled with EHL and study the mutual influence between anisotropic inhomogeneous material and EHL pressure [8,11]…”

“…They found that the subsurface inclusions changed the EHL pressure and film thickness profiles. Morales-Espejel et al [8] used a rapid micro-EHL methodology combined with a multigrid method for stress calculation and surface deformation [9] to study surface fatigue with heterogeneous material under rough lubricated rolling-sliding contact. The inhomogeneities near contact surface affect pressure and subsurface stress distribution.…”