Fatigue of carbon cord-rubber composites: Effect of frequency, R ratio and life prediction using constant life models

The influence of frequency and R ratio on tensile fatigue of carbon cord reinforced HNBR composites has been studied. Frequency was found to have negligible effect on fatigue life, due to minimal heat build-up even at the highest frequency. Longer fatigue life at higher R ratios at a given maximum cyclic stress level was associated with the dynamic process of forming and melting of crystallites during loading and unloading, leading to a crackarresting effect. The applicability of various analytical constant life diagram (CLD) models showed that the modified Harris's CLD and piecewise linear CLD gave a reasonably good agreement with experimental fatigue data.