Adhesive contact and kinetics of adherence between a rigid sphere and an elastomeric solid

Abstract

The adhesive contact of rigid spherical punches on viscoelastic solids is studied using a solution of the axisymmetric Boussinesq problem, assuming an integral constant to be non-zero. The JKR theory, based on the energy balance, is then found. The stress tensor is computed by superposition of the Hertzian stress tensor and the flat punch stress tensor, and is plotted for two particular cases: zero and minimum negative applied loads. It is shown that, whatever the load, the existence of molecular attraction forces provokes infinite stresses at the edge of the contact area. Fracture mechanics concepts are used to study the kinetics of adherence. It is shown that the general equation used allows the kinetics of interfacial crack propagation to be predicted in all types of test: fixed load; displacement; loading velocity; and crosshead velocity. Finally, the problem of the tackiness of elastomers and the dwell time effect on adherence are examined. The experimental results collected in this review have been obtained for the contact surface glass ball/polyurethane. All the theoretical predictions are verified with a reproducibility of better than 2%.