Fatigue Characteristics of Vulcanized Natural Rubber for Antivibration (1st Report, A Study on the Effect of Stress Ratio Focused on Fatigue Damage)

In order to investigate fatigue characteristics of vulcanized natural rubber, fatigue tests were carried out under various stress ratios R. It was considered that the fatigue cracks were initiated from defects in very early stage of total life. The fatigue life was nearly equal to the fatigue crack propagation life and the propagation process was independent of R. The crack growth rate was proportional to the crack length to about the first power, when the crack length was defined as the length of the direction perpendicular to the loading direction. The crack propagation mode was dependent on R. Under 0 < R < 1 condition, the crack tended to propagate along the loading direction because of crystallization.