A FATIGUE-CRACK GROWTH-MODEL FOR RANDOM FIBER COMPOSITES

Fatigue crack growth behavior of a randomly oriented short carbon fibe r reinforced polyether ether ketone (PEEK) composite is studied at fou r different load ratios. Based on the experimental data, a new fatigue crack growth model is proposed which accounts for crack growth throug hout the entire fatigue cycle and not just at the maximum load. The pr oposed model involves a weighted averaging procedure and is found to f it the fatigue crack growth rates at all load ratios in a single power law equation. Finally, it is observed that the fatigue threshold inte nsity of this material decreases with increasing load ratio.