Influence of defects size on the fatigue properties of an industrial EPDM

Fatigue life of rubber components is known to be linked with the defects population. Indeed, cracks initiate around these defects, and propagate until the final failure of parts. In the present work, the defects size influence on the fatigue properties is estimated by drilling calibrated holes of different sizes in pure shear samples and analyzing fatigue crack initiation and propagation stages around these defects. The use of the square root of the area projected on the tensile direction as a representative size measurement allows gathering in the same plot natural defects and calibrated holes results. Finally, it is found that the number of cycles for crack initiation stage is much more influenced by the defects size than the number of cycles for crack propagation stage.