Numerical micro-texture optimization for lubricated contacts—A critical discussion

What is it about?

Despite numerous experimental and theoretical studies reported in the literature, surface micro-texturing to control friction and wear in lubricated tribo-contacts is still in the trial-and-error phase. The tribological behaviour and advantageous micro-texture geometries and arrangements largely depend on the contact type and the operating conditions. Industrial scale implementation is hampered by the complexity of numerical approaches. This substantiates the urgent need to numerically design and optimize micro-textures for specific conditions. Since these aspects have not been covered by other review articles yet, we aim at summarizing the existing state-of-the art regarding optimization strategies for micro-textures applied in hydrodynamically and elastohydrodynamically lubricated contacts. Our analysis demonstrates the great potential of optimization strategies to further tailor micro-textures with the overall aim to reduce friction and wear, thus contributing toward an improved energy efficiency and sustainability.

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Photo by Jon Tyson on Unsplash

Photo by Jon Tyson on Unsplash

Why is it important?

Despite numerous experimental and numerical studies for HL and EHL contacts, surface texturing still largely relies on trial-and-error testing. Although some general design recommendations have been derived in literature, their introduction into industrial applications is hampered by the fact that the tribological performance mostly depends on the respective contact and operating conditions. Therefore, surface textures always must be designed for the underlying kinematics, stresses, and contact situations. Suitable simulation approaches can serve as a numerical zoom into the tribological contact, thus contributing toward the design of surface textures with reduced experimental effort. However, the requirements for numerical modelling are complex due to the involved physical phenomena and multi-scale domains. Consequently, the practical feasibility in an industrial context has been hampered by the lack of publicly available source codes, commercial software solutions and/or detailed recommendations for the consideration of relevant phenomena as well as the lack of a methodology for efficient optimization. These aspects, with a strong focus on numerical modelling of both HL and EHL contacts, as well as the involved optimization approaches have not yet been addressed by other articles reviewing the state-of-the-art in surface microtexturing. Therefore, this article aims at shedding some light on numerical modelling and optimization approaches.