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Human skin is characterised by a complex and highly variable friction behaviour. Although the variation of friction coefficients measured for skin depends on numerous parameters related to the skin itself, the surface in contact as well as contact conditions, water or sweat – either bound in the stratum corneum and manifest as skin hydration or in form of liquid films lubricating the interface – is the most important factor. Here, we analyse the variation of previous experimental data on the basis of the adhesion friction model and show how lower and upper bounds, i.e. envelope functions, can be derived for measured skin-friction coefficients. From these envelope functions, essential tribological parameters such as the interfacial shear strength and the real contact area of skin are estimated. [ABSTRACT FROM PUBLISHER]

In this paper, in-shoe blister formation during running is analyzed and possibilities to reduce these cutaneous lesions by appropriate sock properties are discussed. Six types of cotton-made athletic socks were studied in order to evaluate the influence of the knitted structure on the sock-to-skin friction (terry jersey, plain jersey, and non-raised jersey duffel structures). The contact conditions between a running shoe and foot areas prone to friction blisters were simulated using a linear reciprocating tribometer, and the friction behavior of the socks in contact with a mechanical skin model was investigated. In additional experiments, the shock absorption properties of the socks were measured. Among the investigated socks, the terry jersey fabric knitted in a specific process and a dense, tight jersey structure, i.e. a plain jersey knitted with two yarns, were found to be most suitable for running socks. [ABSTRACT FROM PUBLISHER]