Characterization of Fatigue Behavior in Quasi-Isotropic Laminate of Ceramic Composite

Fatigue damage mechanisms in a quasi-isotropic laminate, [0/ ² 45/90] _s of silicon carbide fiber reinforced calcium-alumino-silicate glass ceramic composite was investigated. Several tests were conducted at different maximum stress levels which intro duced varying degree of initial matrix cracking in 90°, 45° and 0° plies. The initial damage and change in modulus was monitored during the fatigue cycling. Specimens with a considerable amount of initial cracking in 0° plies failed in less than 700 cycles, and others did not fail over one million cycles. The results of this study confirmed the findings of the previous studies regarding the existence of fatigue limit in ceramic composites. The fatigue limit did not correspond to the proportional limit of the static test as reported in the previous studies, however, it corresponded to the initial damage or static loading condition where 0° plies were largely intact.