Fig. 5.
Methodology for determining the optimal and singular shapes for dry adhesion between two solid objects. (a) Deformed configuration of the optimal shape at pull-off. At this state, a uniform stress equal to the theoretical adhesion strength σth is distributed over the contact region. (b) Reverse of the pull-off configuration by superposition of a uniform pressure equal to σth over the contact region, which results in the undeformed configuration of the optimal shape depicted in c. (d) Deformed configuration of the singular shape at pull-off. At this state, a singular stress equivalent to that associated with a crack external to the contact region is assumed to be distributed over the contact interface. (e) Reverse of the pull-off configuration by superposition of a singular pressure distribution over the contact region, giving the undeformed configuration of the singular shape depicted in f.