Nature's blueprints on bearings: Tribological and vibration performance of leaf-shaped textures for thrust roller bearings under starved lubrication

As rolling element bearings operate in challenging environments with insufficient lubrication, innovative surface modifications are needed to enhance their reliability and service life. This study investigates the influence of various leaf-inspired micro-texture patterns on the tribological and vibration performance of cylindrical thrust roller bearings operating under starved lubrication. Thereby, six distinct leaf-shaped textures, namely strawberry, cherry blossom, ginkgo, red maple, bamboo, and acer triangularis were fabricated on the raceways using laser surface texturing. Friction, wear, and vibration responses were systematically evaluated using a vertical tribo-test rig and advanced signal analysis. While most textured bearings exhibited higher friction and wear than the smooth reference, the bamboo-inspired texture achieved modest friction reduction. Guided by these findings, a pine needle-inspired texture was designed, resulting in a significant decrease in average friction by 64% and wear loss by 40% compared to the untextured group, along with reduced vibration amplitudes. The results demonstrate that careful geometric optimization of biomimetic textures, particularly those with slender, vein-like features, can substantially enhance bearing performance under lubrication-limited conditions. These insights provide a pathway for rational design of bio-inspired surface modifications in rolling element bearings, with direct implications for reliability and efficiency in demanding applications.