Analysis and Prediction of Multiple-Site Damage (MSD) Fatigue Crack Growth

A technique was developed to calculate the stress intensity factor for multiple interacting cracks. The analysis was verified through comparison with accepted methods of calculating stress intensity factors. The technique was incorporated into a fatigue crack growth prediction model and used to predict the fatigue crack growth life for multiple-site damage (MSD). The analysis was verified through comparison with experiments conducted on uniaxially loaded flat panels with multiple cracks. Configurations with nearly equal and unequal crack distributions were examined. The fatigue crack growth predictions agreed within 20 percent of the experimental lives for all crack configurations considered.