Jost Institute for Tribotechnology, University of Lancashire
ACCESSIBLE APPROACHES TO MODELLING MIXED FRICTION
Accurate prediction of friction in the mixed lubrication regime remains a key challenge in tribology and engineering design. This talk presents a simple method for calculating mixed-friction coefficients based on a reinterpretation of the classical Stribeck curve. In this approach, the Lambda ratio is used as the independent variable, while the dependent variable is a normalized mixed/boundary friction parameter representing the proportion of boundary friction within the mixed regime. When mini traction machine (MTM) friction data are plotted in this framework, a “universal curve” is obtained, enabling the application of a reverse sigmoid fitting function. The proposed methodology shows good agreement for base oils, while straightforward modifications allow the inclusion of friction modifiers and anti-wear additives in formulated lubricants. Furthermore, the approach can be extended to account for surface topography effects, providing a versatile tool for friction modelling in practical tribological systems.
Prof. Ian Sherrington is Director of the Jost Institute for Tribotechnology at the University of Lancashire in the UK. His research interests focus on the measurement and prediction of a wide range of tribological parameters and the development of active (tribotronic) machine elements. He is the immediate past chair of the IMechE Tribology Group Committee in the UK, Executive Director of the International Tribology Council and an Affiliate Professor at the Royal Institute of Technology (KTH) in Stockholm.