Fatigue Behavior of Cord-Rubber Composite Materials under Different Loading Conditions

Cord-rubber composites are subjected to a wide range of loads in various applications. However, their fatigue behavior remains relatively under-researched. To address this gap, a set of representative specimens was developed, and a validated numerical model was employed to assess fatigue-relevant parameters. In this study, we present the results from two series of tests with different strain ratios (<i>R</i> values). One series was subjected to a pure pulsating tensile strain (<i>R</i> ~0), while the second series experienced an increased mean strain with an <i>R</i> ratio between 0.2 and 0.3. A direct comparison of the two series demonstrated that a higher strain ratio results in a longer service life. This is reflected in an increase in the slope (<i>k</i>) from 13 to 23, as well as an increase in the ultimate fiber strain from 8% to 11% at <i>N_d</i> = 50,000 load cycles for a survival probability of 50%. Both series indicate a comparable scatter in the test results. This comparative analysis shows that the strain ratio significantly impacts the fatigue behavior of cord-rubber composite materials based on cyclic tests under different loading conditions. The findings of this study demonstrate the necessity of considering different load situations when evaluating or designing components.