There are several drivers demanding improved tribological models, including: (i) the quest for sustainability in energy and material consumption, (ii) the need for better tools to predict the reliability and performance of engineering components, (iii) the rapid development of micro- and nano-technologies and the need to make these function effectively. Over the coming decades, improved efficiency and reduction of friction in mechanical systems, understanding of biological systems, as well as miniaturisation will all require a better description of tribological interactions at the micro-, meso- and macro- scales. Hence, the development of advanced strategies to integrate models that provide information at different scales and are governed by strongly coupled mechanical, physical and chemical mechanisms are strongly needed. The key is to provide predictive capabilities by integrating the models across the scales. In this talk, recent developments made to build models adopted in tribology to provide a complete mechanical/physical/chemical description of the underlying mechanisms will be presented.
Another very important aspect to consider is that most research in tribology either treats rubbing contacts as steady-state or as cyclic systems, or is based on a single snapshot taken at the end of a rubbing process. In practice systems are dynamic and evolve during operation, for example in terms of boundary film formation, surface and sub-surface damage accumulation, lubricant compositional changes etc. The evolution of lubricated systems is initiated at the atomic and molecular scale but is driven by, and is perceived at the macroscale. The challenge is thus to develop models underpinned by dedicated experiments carried out at different scales. However the majority of experiments cannot access molecular scales and it is thus important to model intermediate scales in the most accurate way so that there is no loss of information when trying to “jump” directly from atomistic and molecular to continuum models. Examples here will be provided where different modelling schemes are used to capture surface roughness, adhesion, rheology in confinement and other important tribological phenomena using the right set of tools at the right scale; integration of these tools and their link with micro- and macro-scale models are key to providing predictive capabilities that can be used to improve performance of engineering components and produce innovative solutions.