Loading conditions impact on the compression fatigue behavior of filled styrene butadiene rubber

Fatigue failure, commonly encountered in rubber materials, is a critical issue. In this study, the compression fatigue tests of filled styrene-butadiene rubber (SBR) under different loading conditions were performed, applying cylindrical specimens. A stress-strain curve and modulus drop curves were generated by nine fatigue loading cases, covering different R ratios in the range of 0 < R < 1. The temperature variation in the process of compression fatigue was explored. Three different approaches were applied to investigate the fatigue life of the SBR (it is used twice hence abbreviation should be used) vulcanizates. These methods were validated in assessing the fatigue failure of the specimens. According to the experimental fatigue life, a fatigue life prediction model based on strain amplitude as the damage parameter was established. The results demonstrated that both R ratio and strain amplitude could affect the fatigue life. For all the loading cases, the fatigue life generally increases with the increase of R ratio. Under the compression loading condition, the narrower range of strain and the lower mean strain are beneficial to the fatigue resistance of rubbers, which also indicates a larger pre-load provides much higher fatigue resistance. During the fatigue loading, the temperature rises rapidly until it reaches a peak value, then drops slightly, and finally reaches a plateau.