Multiaxial Fatigue Crack Initiation on Filled Rubbers: Statistical Aspects

Abstract

White reinforcement fillers such as precipitated silica inclusions are traditionally used in order to increase tear resistance and reduce internal heating of technical rubber components. In this work, two precipitated silicas, which essentially differ in their specific surface area, are incorporated into a natural rubber matrix and investigated according to their mechanical behaviour and fatigue lifetime. To this end, cyclic tension/compression and torsion tests have been carried out on dogbone shaped specimens. All tests have been performed until a visible millimetric crack appears on the outer surface of the specimens. Microscopic examinations are utilised in order to find out the crack growth mechanisms in both materials.While a significant difference has been observed in terms of mechanical properties, the fatigue curves seem to merge into a unique diagram for both reinforced rubber materials. The location and the orientation of the cracks are taken into account by using the largest principal stress. Furthermore, a statistical analysis is performed based upon the amount of specific inclusions per cm 3 of the rubber compound.