Singular dynamics in the failure of soft adhesive contacts

TL;DR

This study investigates the singular dynamics during the failure of soft adhesive contacts, revealing how gels recover after detachment through surface stress relaxation and viscous flow.

Contribution

It introduces a detailed characterization of the failure and recovery process in compliant gels, highlighting the singular nature of the detachment dynamics.

Findings

Gel recoils with a power-law surface profile post-detachment

Detachment dynamics driven by surface stress and viscous flow

Importance of both liquid and solid phases in gel mechanics

Abstract

We characterize the mechanical recovery of compliant silicone gels following adhesive contact failure. We establish broad, stable adhesive contacts between rigid microspheres and soft gels, then stretch the gels to large deformations by pulling quasi-statically on the contact. Eventually, the adhesive contact begins to fail, and ultimately slides to a final contact point on the bottom of the sphere. Immediately after detachment, the gel recoils quickly with a self-similar surface profile that evolves as a power law in time, suggesting that the adhesive detachment point is singular. The singular dynamics we observe are consistent with a relaxation process driven by surface stress and slowed by viscous flow through the porous, elastic network of the gel. Our results emphasize the importance of accounting for both the liquid and solid phases of gels in understanding their mechanics, especially under extreme deformation.