A perspective method for the identification of the transverse and longitudinal residual internal stress in aluminium T-joint FSW. First evidences

In the aircraft industry a strong demand for weight reduction is mainly oriented to the requirements of a more stringent containment of pollution and lower fuel consumption. The potential offered by innovative joining technologies such as welding Friction Stir Welding (FSW) and other, known for some time, allow to hypothesize a significant reduction of weight. Starting from these considerations, the aim of this work is the determination, through a technical and non-destructive method, of the residual internal stresses of aluminium T-joint skins welded by means of the FSW technology. In particular the goal of this paper is to illustrate the selective capacity of the proposed methodology for the identification of longitudinal and transverse stresses. In the first part of the work a brief introduction to the problem is presented; in the second part were described the specifications of the FSW process and the materials welded in T-join configuration used. In the third part was described the non-destructive method proposed for determining internal stress state of aluminium T-joint skins. In the last part of this paper were reported the results obtained by applying the method to the welded T-joints with the FSW technology