Comparison of AA 2024 T3 friction stir welded and riveted overlap joints with the addition of a pressurization test

The aim of this work is to investigate the Friction Stir Welding (FSW) process applicability to a typical aeronautical joint: the union of the stiffeners to sheets constituting the fuselage. To do this analysis FSW parameters of flat overlapped sheets were first identified by monitoring the temperature reached using thermography. 1.3 mm thick AA 2024 T3 overlapped sheets were welded with success and the thermal effect due to the use of different welding parameters was compared with the results of mechanical tests and microstructural investigations. FSW joint mechanical properties were compared with those detected by performing tensile tests of joints made by riveting, showing absolutely comparable values. FSW identified parameters were used to make overlap joints between flat panels and stiffeners, so as to realize a typical structure of the aeronautical sector and to compare, by pressurization tests, the resistance of such panels with similar riveted. The innovative character of this research is represented by cyclic pressurization tests, conducted as indicated by the FAR (Federal Aviation Regulation) rules on a scale model. Thus it was possible to verify that the fatigue strength of welded panels is such as to overcome the acceptability limits fixed in the aeronautical field.