Multilayer Modelling of Lubricated Contacts: A New Approach Based on a Potential Field Description

A first integral approach, derived in an analogous fashion to Maxwell’s use of potential fields, is employed to investigate the flow characteristics, with a view to minimising friction, of shear-driven fluid motion between rigid surfaces in parallel alignment as a model for a lubricated joint, whether naturally occurring or engineered replacement. For a viscous bilayer arrangement comprised of immiscible liquids, it is shown how the flow and the shear stress along the separating interface is influenced by the mean thickness of the layers and the ratio of their respective viscosities. Considered in addition, is how the method can be extended for application to the more challenging problem of when one, or both, of the layers is a viscoelastic material

On a Model for the Prediction of the Friction Coefficient in Mixed Lubrication Based on a Load-Sharing Concept with Measured Surface Roughness

A new model was developed for the simulation of the friction coefficient in lubricated sliding line contacts. A half-space-based contact algorithm was linked with a numerical elasto-hydrodynamic lubrication solver using the load-sharing concept. The model was compared with an existing asperity-based friction model for a set of theoretical simulations. Depending on the load and surface roughness, the difference in friction varied up to 32 %. The numerical lubrication model makes it possible to also calculate lightly loaded contacts and can easily be extended to solve transient problems. Experimental validation was performed by measuring the friction coefficient as a function of sliding velocity for the stationary case

Thermo-Hydrodynamic Analysis of Tilting Pad Journal Bearing with General Purpose CFD Software

This paper presents a prediction model for tilting pad journal bearings (TPJB), based on a general-purpose CFD software. Currently, the industrial manufacturers use ad-hoc proprietary codes for the design of TPJB and the prediction of their performance. However, apart from the input parameters defined by the code developer, the user can not modify the model. On the contrary, with a general-purpose software the user can implement modifications and exploit well developed toolboxes. In particular one can adopt up-to-date turbulence models and study fluid structure interaction with specific tools. A procedure was developed, based on ANSYS-CFX, to predict the static characteristic of a TPJB, such as load capacity, film temperature, flow rate and friction torque. A thermohydrodynamic model is presented and results, obtained with different boundary conditions, are compared