Ductile damage development in friction stir welded aluminum (AA2024) joints

Ductile damage development in a friction stir welded aluminum joint subjected to tension is analyzed numerically by FE-analysis, based on a total Lagrangian formulation. An elastic-viscoplastic constitutive relation that accounts for nucleation and growth of microvoids is applied. Main focus in the paper is on the interaction between changes in the material parameters in different regions of the weld, the damage development and the position of the final fracture. Especially changes in the yield stress profile transverse to the weldline are examined, since some process parameters have been shown experimentally to affect this. It is found that damage development is highly influenced by changes in the yield stress profile and a shift in final failure is shown for comparable yield stress in the thermo-mechanically affected zone (TMAZ) and the nugget zone (NG).