Shear fatigue of the bonded and frictional interface under constant normal pre-stress

Fatigue damage in the idealised bonded interfaces under constant normal pre-stress is studied by scanning electron microscopy and it is found to involve several microstructurally small cracks with different lengths and orientations. Evolution of fatigue damage in the adhesive occurs as the small cracks grow, coalesce and interact with each other. The theory related to these phenomena is not yet established. Therefore, a phenomenological model of fatigue damage is proposed based on the experimentally-measured compliance of the modified napkin ring specimen. The cohesive zone law describing the quasi-static fracture of the interface is re-formulated to include the effect of fatigue damage.