Description of fatigue damage in carbon black filled natural rubber

The present paper deals with fatigue damage at the macroscopic scale in carbon black filled natural rubber under uniaxial loading conditions. Uniaxial tension-compression, fully relaxing uniaxial tension and non-relaxing uniaxial tension loading conditions were applied until samples failure. Results, summarized in a Haigh diagram, show that only one type of fatigue damage is observed for uniaxial tension-compression and fully relaxing uniaxial tension loading conditions, and that several different types of fatigue damage take place in non-relaxing uniaxial tension loading conditions. The different damage types observed under non-relaxing uniaxial tension loading conditions are closely related to the improvement of rubber fatigue life. Therefore, as fatigue life improvement is classically supposed to be due to stress-induced crystallization, a similar conclusion can be drawn for the occurrence of different types of fatigue damage.