An Enhanced Stochastic Two-Scale Model for Metal-to-Metal Seals

• Main Authors: Francesc Pérez-Ràfols, Andreas Almqvist
• Format: Article
• Language: English
• Published: MDPI AG 2018-10-01
• Series: Lubricants
• Subjects: leakage; contact mechanics; reynolds equation; two-scale modelling; stochastic; metal-to-metal seal
• Online Access: http://www.mdpi.com/2075-4442/6/4/87

Leakage in static metal-to-metal seals is predominantly determined by the topography of the contacting surfaces. The topography consists of features that span the entire range from its carefully engineered geometry down to micro-sized surface asperities. The mesh density necessary to fully resolve all the features, in this large span of length scales, generates too many degrees of freedom for a direct numerical approach to be applicable. Some kind of sophistication, either incorporated in the mathematical model or in the numerical solution procedure or even a combination of both is therefore required. For instance, in a two-scale model, the geometrical features can be addressed in the global-scale model, while the features belonging to length scales smaller than a given cut-off value are addressed in the local-scale model. However, the classical two-scale approaches do not explicitly address the stochastic nature of the surfaces, and this has turned out to be a requirement in order to obtain quantitative predictions of leakage in metal-to-metal seals. In this work, we present a continued development of an already existing two-scale model, which incorporates a stochastic element. The novelty lies in the way we characterise the permeability at the local scale and how this is used to build a more efficient and useful approach.