Edge effects in adhesive and non-adhesive indentation: Experimental and numerical insights

The indentation test of a steel indenter on soft rubber is conducted with a focus on investigating how the indenter location influences the contact behavior. It is observed that when the indenter is positioned close to the edge of the rubber block, the shape of the contact area becomes noncircular, and the normal force required to indent the rubber to the same depth is smaller compared to the case when the indenter is farther from the edge. To explore the effect of edge in adhesive contact, a sticky rubber with a lower elastic modulus is used. The adhesive contact behavior exhibits a distinct peak in adhesive force at an intermediate distance from the edge, after which the adhesive force decreases as the indenter moves farther from the edge. Numerical simulations are performed to discuss the mechanisms behind the observed adhesion enhancement. These simulations suggest that the asymmetry in the contact area and the pinning effect at the edge play a significant role in increasing the adhesive force.