Environmental fatigue of unidirectional glass-carbon fiber reinforced hybrid composite

Unidirectional glass fiber reinforced and glass-carbon fiber reinforced (glass to carbon fiber volume ratio 3:1) epoxy matrix composite samples were subjected to tension-tension fatigue in air and in distilled water at 25°C. While no significant change in fatigue life was observed for both types of samples tested in air and in water when cyclically tested at 85% of average ultimate tensile strength (UTS), the detrimental effect of water becomes apparent at lower stress levels of 65 and 45% UTS. Compared to samples tested in air, cyclic loading in water results in shorter fatigue lives for both glass and hybrid samples. While all of the glass fiber composite samples did not survive to 10⁶ cycles when loaded in water, hybrid samples showed better retention in structural integrity under environmental fatigue for lives up to 10⁷ cycles, a consequence of the corrosion resistant of carbon fiber. Thus, by incorporating appropriate amount of carbon fibers in glass fiber composite, a much better performance in fatigue can be achieved for glass-carbon hybrid composite.