Fatigue behaviour of rubber is a very important characteristic due to its extensive use in many
engineering applications. In most applications, rubber is commonly subjected to fluctuating loads,
which often lead to failure due to the nucleation and growth of defects or cracks. Due to their
viscoelastic behavior, rubbers have a high damping ability. Very often rubbers are subjected to
different frequencies in the service, such as engine mounts. The effect of frequency on the fatigue
lifetime needs deep investigations. In present work, the effect of frequency on the styrene
butadiene (SBR) and nitrile-butadiene rubber (NBR) with 0,20,30,50 and 70 Phr of carbon black
was investigated. It was found that the fatigue lifetime decreased with the increase of the
frequency. Increasing carbon black (CB) contents in rubber improved the fatigue resistant and
increased of the fatigue lifetime.