Residual strength research for aluminum alloy sheet with multiple site damage

This study investigated the residual strength of aluminum alloy sheet with multiple site damage (MSD) through three types of aluminum specimens test. Aluminum panels with bare collinear constant diameter holes were chosen as specimens. And there were saw cuts at both edges of all the holes. After some constant amplitude tension-tension load cycles, the MSD were found in these specimens since there were multiple fatigue cracks emanating from the saw cuts of holes. The residual strength was recorded as the maximum load when every specimen was subjected to monotonically increasing tensile load until failure occurred. The test results were compared with predicted residual strength results by five different failure prediction criteria that were often used in engineering in order to evaluate the accuracy of these criteria. The failure criteria included: fracture criterion, net ligament loss criterion, ligament yield criterion, CTOA/CTOD criterion and average stress criterion. Ligament yield criterion (Swift criterion) and average stress criterion got more accurate prediction results than other criteria.