Fatigue Damage Of Textile Cord-Elastomer Composites under Compression-Tension Loadings

Compression-tension fatigue significantly damages textile cord-elastomer composites used in industrial products. However, conventional fatigue test methods only allow limited control over these conditions. This work introduces the new Extension-Compression-Uniaxial (ECU) fatigue test. This test allows for strict uniaxial loading with separate control over tensile and compressive strain amplitudes, while keeping a specimen design that reflects industrial applications. The ECU test is validated through a comparative fatigue study on textile cords made from different filament materials, cord constructions, and elastomer matrices. These cords were subjected to pure tension, pure compression, and combined compression-tension loading. The experiments reveal clear differences in damage development across loading modes. Combined loading leads to the most significant drop in mechanical performance. In contrast, pure compression affects mainly the elastomer matrix, while tensile loading highlights damage growth within the cord. Temperature and number of cycles greatly influence fatigue progression. Variations in elastomer stiffness have a limited impact within the investigated range. Post-mortem X-ray tomography and scanning electron microscopy highlight the multiscale damage processes triggered by different loading scenarios, revealing distinct failure mechanisms at the filament level. The results show that the ECU test is a useful tool for isolating and studying fatigue damage mechanisms in reinforced elastomer systems under complex loading conditions.