A Modified Model for Static Friction of a Soft and Hard Solid Interface

TL;DR

This paper introduces a modified static friction model for soft-hard interfaces that incorporates both bond formation and rupture, improving prediction accuracy and emphasizing the role of molecular bonds over residual stress effects.

Contribution

The model advances static friction understanding by including bond formation dynamics, aligning predictions closely with experimental data for soft-solid interfaces.

Findings

The model accurately predicts static friction in experiments.

Bond formation significantly influences static friction.

Residual stress does not affect static strength.

Abstract

We present a modified model based on shear rate and aging time dependent static friction between a soft solid such as gelatin hydrogel and a hard surface for instance glass surface. Earlier the model for static friction (Juvekar and Singh, 2016) considered only the bond rupture process as a result, the friction model over predicts the static friction in the experiment. The friction model now takes into account both formation and rupture of molecular chains at the sliding interface. It is also assumed that age of the newly formed bonds during the rupture process is the same as the aging time. As a result, the model predicts quite well the experimental data and thus highlighting the significance of bond formation in static friction. Moreover, it is also observed that residual stress has no effect on static strength.