This research focused on studying the influence of friction stir welding (FSW) factors-such as the type of the welding tool, the speed of the welding tool and the welding speed-on the impact toughness of the panels made of AA6061-T6 aluminum alloy sheets with thickness of 3mm. The aluminum alloys have multiple uses in industry, but are quite difficult to be welded by fusion welding processes, including MIG welding, and laser welding. By using a milling machine, it was possible to employ the FSW process, applying four constant welding speeds (800, 1000, 1250, 1600 rpm) and three welding speeds (32, 63, 80 mm/min). Tool pins with square cylindrical and threaded tapered cylindrical profiles were used in the experimental programme. The machined samples were subjected to Charpy V notch impact test at room temperature and the results were compared to the impact energy of the base metal. The results show higher values of the impact energy when the tool pin used has square profile.

To investigate the reaction forces produced by the change in momentum of a water jet, an experimental and computational fluid dynamics (CFD) study are carried out. In the experiment, the water jet forces on a test horizontal hemispherical cup are measured. ANSYS CFX simulation code is used to provide a 3D CFD simulation of a circular cross section water jet released from a nozzle and moves upward in the air before striking a horizontal hemispherical cup and a flat plate. The progress in the CFD simulation within the last decade make it possible to analyze and visualize the flow pattern of complex multiphase free surface fluid flow. The simulated forces of the vertical water jet against a horizontal hemispherical cup using ANSYS CFX code are compared with the experimental forces generated by the water jet as it strikes a hemispherical cup. A good agreement is found in the CFD results compared with the experimental results. 21.649 % was the maximum percent difference recorded at 0.245 kg/sec flowrate and 0.484 % was the minimum percent difference at 0.368 kg/sec flowrate.

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