Elastoplastic fracture analysis of thin notched AA7075-AA2024 dissimilar friction-stir-welded plates under mixed mode I/II loading

In this research, fracture of friction-stir welding (FSW) of AA2024-T3 and AA7075-T6 aluminum alloys weakened by notches is studied. In the experimental part, a rectangular specimen, called U-notched diagonally loaded square plate (UNDLSP) and made of welded AA2024-T3 and AA7075-T6 aluminum alloys, is used for fracture tests under pure mode I and mixed mode I/II loading conditions. For fracture tests, different notch tip radii and different ratios of loading mode combinations are considered. In the theoretical part, due to ductility of the material under test, combination of the equivalent material concept (EMC) with two brittle fracture criteria (maximum tangential stress and mean stress criteria) is used to predict the load-bearing capacity (LBC) of the samples. By comparing the experimental and theoretical results, it is revealed that both criteria in combination with EMC are able to predict the LBC of the U-notched samples well and with high accuracy.