2017 年 62 巻 8 号 p. 532-536
The tribological properties, such as static friction, of compliant elastic materials have proven important for industrial applications, including seals, windshield wipers, robot hands, grips on tools, and sports equipment. Deformable surfaces with designed microstructures may provide characteristic tribological properties based on their complex contact states. Here the static friction is investigated, over a wide range of normal loads, between a flat glass surface and textile-embedded elastomer surfaces that show hierarchical microstructures. The microstructures comprise small protrusions on each textile fiber and surface-buckling-based wrinkles with periodicities on the order of tens and hundreds of microns, respectively. The static friction becomes increasingly higher with increases in the normal loads applied to the structure surfaces. Observations of the contact areas reveal that the contact states nonlinearly change with changing normal loads. In addition, the wavy shapes are flattened at high loads. This unique, load-dependent static friction, associated with the transition from partial to almost full contact, depends on both the normal loads and the aspect ratio of the wrinkles. By tuning the structure of wrinkles, it is possible to extend the monotonic load-dependency of friction into the highly nonlinear range, which may augment the tribological performance of elastomeric materials.
