Effect of retraction speed on adhesion of elastomer fibrillar structures

We studied the dependence of adhesion on retraction speed in elastic fibrillar structures. The evolution of the real contact area and crack propagation speeds at the contact interface was characterized during retraction using a custom measurement system. The experimental results showed an increase in the average crack propagation speed and the rate of change of real contact area during pull-off, for increasing retraction speed. Our results indicate that during pull-off, the critical contact area does not have significant contribution to rate-dependent adhesion, whereas rate of change in the contact area and the crack propagation speed contribute significantly to rate-dependent adhesion.