Grip mechanisms and mechanical characterization of outsole materials: towards shoe slip resistance prediction

Slipping-related falls are a prevalent source of injuries that have driven the development of various experimental devices to assess the slip resistance of footwear products. These devices are useful for testing existing solutions and identifying the most suitable products for a specific use. During a slip event, the mechanical loadings undergone by the outsole material are generally strongly heterogeneous, leading to a coupling between the stud geometry and the material mechanical behaviour (Jones et al., 2018). Most of the previous studies emphasize the role of the viscoelastic properties on the slip resistance but the experiments are often performed using commercially available footwear products with a large range of outsoles geometry and materials; making the conclusion difficult to generalize. More specifically, the exact solicitations frequencies applied on the outsole are still unknown, hindering the identification of the targeted material properties for optimizing the slip resistance of the outsoles. Among the challenges to overcome to optimize the slip resistance of the shoes, finely identifying the aforementioned properties is a critical issue and requires isolating the contribution of the material from the geometry of the outsole.