Fretting Behavior of Biomimetic-Textured Silicone Rubber Under Varying Wetting Conditions

A textured surface can significantly enhance the tribological properties of a robotic soft gripper in wet environments. However, external disturbances such as wind, sound waves, water flow, and mechanical vibrations often lead to fretting contact on the soft gripper's surface. This article imitates the toe pad texture of tree frogs, renowned for their strong climbing abilities, to prepare silicone rubber films with hexagonal textures of different sizes and experimentally studies their fretting behavior under both deionized water and silicone oil wetting conditions. The effects of texture size, normal force, wetting condition, displacement amplitude, and frequency on the fretting behaviors of silicone rubber films are discussed in detail. The results indicate that textured surfaces significantly enhance the coefficient of friction (COF) of silicone rubber under wetting conditions with a small normal force and high frequency. Furthermore, the larger the texture size, the more noticeable the increase in COF.