Effect of work of adhesion on contact of an elastica with a flat surface

Abstract

The JKR technique has enjoyed widespread usage in recent years for measuring the work of adhesion between an elastomeric cap and substrates of interest. Although some success has been seen in coating the cap with other materials, the requirement that one of the contacting members be elastomeric remains an important feature of the test. The use of a soft structure instead of a soft material for the flexible contact element is proposed here. A flexible strip is bent and then pushed onto a rigid horizontal surface. First a JKR type of analysis is carried out, in which the surface energy is assumed to be proportional to the contact area, and the effects of adhesion are represented by a bending couple at the two separation points of the strip with the surface. For a given work of adhesion, the magnitude of the unknown couple is varied until the total energy is minimized. Then a DMT type of model is considered, with forces acting in the cohesive zone outside of each separation point. The forces are either constant or are linear functions of the gap. For both analyses, the effect of adhesion on the contact length, displacements, and forces is investigated. The results can be applied to determine the work of adhesion, based on measurements taken from such a contact problem.