Physics-based modeling of the temperature-dependent fatigue behavior of natural and synthetic polyisoprene rubbers

The mechanical properties of rubbers are typically highly sensitive to temperature, and fatigue crack initiation resistance is no exception. Despite abundant documentation in the scientific literature, the mechanisms driving this temperature dependence remain insufficiently understood. A common approach to addressing this phenomenon is the time-temperature equivalence method. Although it offers reasonably accurate results, it lacks predictive power due to its empirical nature. This article introduces a novel predictive model for the S-N curves of rubbers with respect to temperature, grounded in the Work-Heat Equivalence Principle. This innovative framework is built on a robust physical foundation, with its predictive accuracy enhanced by the absence of fitting parameters. The model's performance is evaluated using an extensive dataset, including newly acquired experimental data, literature-derived results from temperature-controlled fatigue tests on isoprene rubber (IR), and insights from fatigue tests performed on thick rubber parts accompanied by self-heating-induced temperature rises reported in previous studies. The good correlation between the model's predictions and experimental observations underscores the significant role of the proposed mechanism in governing the temperature dependency of rubber fatigue life. • A physics-based model is developed to predict the temperature-dependent fatigue life of rubbers • It relies on the Work-Heat Equivalence Principle and is comparable to Continuum Damage Mechanics to some extent. • The model requires no fitting parameters and yields accurate predictions (RMSE < 30%) • The model can be coupled with the Cracking Energy Density to account for multiaxiality.