Effect of Stress Ratio on the Fatigue Crack Growth Behaviour of C/C Composites

INTRODUCTION C/C composites have been used for aerospace application due to their excellent properties such as low density, high heat resistance in inert gas atmosphere, high specific strength and etc. Since C/C composites have relatively higher fracture resistance than other CMCs, this material can also be used as structural components with high reliability. The fatigue properties are also important in long-time use of C/C composites as a structure. Although many researchers have been studying the mechanical properties of this material, its properties related to fatigue have not been studied in sufficient details so far. In this study, tension-tension fatigue tests were performed with compact tension specimen of C/C composites with 0/90 layers. The effect of stress ratio on fatigue crack growth behaviour was also investigated based on fracture mechanics.