Fractal surface-based three-dimensional modeling to study the role of morphology and physiology in human skin friction

Human skin plays an important role in our perception of contact made throughout the day. In this work, we study the interplay of various morphological and physiological factors that dictate its contact mechanics. A hybrid computational-empirical approach is developed to model skin friction and to understand the role of roughness in contact mechanics of human skin variations in structural properties. A fractal rough surface is considered to model the skin surface. A layered three-dimensional finite element model is generated with stratum corneum, viable epidermis, and dermis which is further used to determine its mechanical response under normal loading. An empirical relationship is then used to predict the coefficient of friction. The effects of varying the Young's modulus, roughness parameters, thickness of stratum corneum and domain size are studied. Simulations are performed for multiple realizations to quantify statistical variations. Our results show that the proposed approach can replicate several experimental findings from the literature such as the decrease in skin friction with humidity and increasing roughness. The study provides qualitative and quantitative insight into the role of roughness in the contact mechanics of human skin while accounting for the effects of micro-level interfacial phenomena.