Liao-Liang Ke

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.

Surface texture, as an important surface engineering technique, can enhance the tribological properties of contact surfaces. This work presents the experimental investigation of the fretting wear behavior of silicone rubber films with biomimetic surface texture under a spherical indenter. Inspired by human fingerprints and tree frog toe pads, hexagonal loop textures with three different texture spacing are created on the surface of silicone rubber films. Three types of indenters are considered: stainless steel, polypropylene, and silicone rubber. The impact of texture spacing, displacement amplitude, normal force, frequency, and indenter material on fretting wear behaviors is discussed in detail. The wear volume is measured by the three-dimensional white light profiler. The surface wear morphology and fretting wear mechanism of textured surfaces are analyzed using a scanning electron microscope. It is found that adding surface texture can effectively decrease the coefficient of friction (COF) of silicone rubber. In addition, the smaller the texture spacing, the more pronounced COF decreases, and the lower the specific wear rate.