ADHESION AND FRICTION BETWEEN A SMOOTH ELASTIC SPHERICAL ASPERITY ANDA PLANE SURFACE

Attempts to establish the relationship between adhesion and friction a t the contact of solid surfaces has been frustrated by their inevitabl e roughness. The recent development of nanotribology, in which a singl e asperity contact can be modelled in the surface force apparatus (SFA ) or the atomic force microscope (AFM), has made possible the simultan eous measurement of friction and adhesion in a sliding experiment. For the case of pure adhesion, continuum mechanics models exist which ass ist in the interpretation of the measurements. In this paper these mod els are extended to include both static and sliding friction. The appr oach is through the concept of fracture mechanics, in which the rate o f release of elastic strain energy is equated to the work done against surface forces, both frictional and adhesive. The model appears to be consistent with currently available experimental data.