Most major aircraft manufacturers use friction-stir welding (FSW) to join aluminum parts. The trick is that the aluminum never reaches its melting point and hence prevents typical solidification defects found in fusion type welding.
One of our Predictive Engineering engineers worked to develop a simulation package that can model the weld process using smoothed particle hydrodynamics on the graphical processing unit (GPU). The simulation code allows the engineer to predict joint efficiency, cleanliness (minimal defects) as well as residual stresses and deformations. That quick simulation is a huge advantage for our FSW-using clients. See our simulation video below, or at https://youtu.be/knrbYckgmqg