A model for frictional stress relaxation at the interface between a soft and a hard solid

•Model for stress relaxation during hold phase of slide-hold-slide experiment of polymer block on hard surface is developed.•Model incorporates aging and velocity dependent strengthening of bonds between pendent chains of block and hard surface.•Model is validated using experiments on stress relaxation of gelatin block on glass surface and scaling laws proposed.•Model predicts residual stress during relaxation process and shows that it is independent of sliding velocity.•Model predicts velocity strengthening and velocity weakening regimes of friction stress along with the transition velocity. In this article, we present a model for the dynamics of relaxation of friction stress at the interface between a soft and a hard surface during the hold phase of the slide-hold-slide (SHS) experiment. The proposed model assumes that during the stress relaxation process, the bonds between dangling chains at the sliding interface undergo strengthening, the extent of which depends on both the age of the bond as well as the sliding velocity. The model predicts the existence of the residual stress, which corresponds to the point of incipient adhesion of the sliding surfaces. The model is validated using experimental data, obtained from the literature, concerning sliding of gelatin hydrogels on glass substrate. Using the values of the parameters estimated from the regression analysis of the experimental data, the scaling laws based on dynamic shear modulus of gelatin hydrogel have been proposed. [Display omitted]