Ductile Failure Prediction of Friction Stir Welded AA7075-T6 Aluminum Alloy Weakened by a V-notch

With increasing applications of the Friction Stir Welding (FSW), a proper study of the fracture behavior is required. In this research, fracture behavior of AA7075-T6 alloy joint made by FSW is investigated by evaluat-ing a fracture test on the Diagonally Loaded Square Plate (DLSP) specimen containing a V-notch, under various loading conditions. Significant plastic deformation takes place around the notch tip at the propagation instance, which shows the elastic-plastic behavior of the welded joint. Ductile failure needs some elastic-plastic fracture mechanics criteria, which are complex and time-consuming. To deal with this, the Equivalent Material Concept (EMC) was applied via replacing a virtual brittle material with a ductile material by equating the tensile behavior of the welded material. In order to predict the Load-Carrying Capacity (LCC) of the FSW DLSP specimens, the EMC was used, which is in conjunction with two brittle fracture criteria called the Maximum Tangential Stress (MTS) and the Mean Stress (MS). Finally, results indicate that with a slight difference, two mentioned criteria could predict the LLC of the V-notched specimens.