Abstract:

Under various strain ratios (R=max/min) loads and variable amplitude loading, uniaxial fatigue experiments are carried out for dumbbell cylindrical specimens of filled natural rubber, and the effect of variable amplitude loading on fatigue life is investigated. Based on the fatigue measurement data, a unified fatigue prediction model with equivalent strain amplitude damage is established. The predicted life of cylindrical specimen is within a factor of two compared to tested life underR>0 andR<0 loading conditions. Variable amplitude loadings are selected to show the effects ofR-ratio, load level, load sequence and dwell periods on uniaxial fatigue life test. The predicted life under variable amplitude loading based on Miner linear damage rule and the unified life prediction model is fully within a factor of two compared to measured life. The dumbbell specimens are tested under random loading. The predicted life is calculated based on rain-flow count and unified fatigue prediction model, while the maximum error is less than 34% for tested and predicted life. The proposed unified fatigue life prediction model and Miner linear damage rule can be used to estimate the fatigue life of a filled natural rubber component under variable loading conditions.

Key words: fatigue life, filled natural rubber, life prediction, strain ratio, variable amplitude loading