Simulation of the global response of a friction stir weld using local constitutive behavior

The local and global mechanical responses of friction stir welded AA-2024 were studied experimentally and modeled using the finite element technique. A technique employing tensile testing and digital image correlation was used to obtain the full field strain distribution in transversely loaded welds, as well as the local constitutive behavior of the various weld regions. Two-dimensional, plane stress and plane strain, finite element models of the welded specimen were constructed using the local constitutive properties as input data and the local and global responses in tension were simulated. Nearly plane stress conditions were found to exist in the specimen as demonstrated by the correspondence between experimental results and the predictions of the 2-D models. These findings were further corroborated by use of a 3-D finite element model. The 3-D model was also used to examine the constraint developed in specimens of various widths.