Unique load dependency of static friction of wrinkles formed on textile-embedded elastomer surfaces

We investigate, over a wide range of normal loads, the static friction on textile-embedded elastomer surfaces that show hierarchical microstructures tunable by adjusting internal in-plane compressive strains. These microstructures, under compression, comprise small protrusions on textile fibers and surface-buckling-based wrinkles with periodicities on the order of tens and hundreds of microns, respectively. The static-friction coefficients unexpectedly increase under normal loads. This unique property, associated with the transition from partial to almost total contact, depends on both loads and the aspect ratio of the wrinkles. Wrinkle-structure tuning modulates load-dependent friction’s nonlinearity, which may augment the tribological performance of elastomeric materials.