At the DYMAT Conference in Switzerland last week CASA PhD candidate Jens Kristian Holmen presented how welded extruded aluminium behaves when it gets shot at.

The study demonstrates a purely numerical procedure for predicting the perforation resistance of welded extruded AA6082-T6 aluminum profiles.

Independent numerical work

The numerical work was conducted completely independent of the experimental tests that were only used for validation purposes. The outline of the three-step numerical procedure is as follows: (1) the temperature development due to a specified welding process is predicted by a thermal solver, (2) based on the chemical composition of the alloy, the temperature-time history during aging and welding, the yield strength and flow stress of the material were determined; and (3) the ballistic limit velocity is found using explicit finite element simulations.

Close correlation – slight degradation

The experimental validation program is described and it shows that the ballistic limit velocities found from the impact experiments correlate closely with the numerically predicted values obtained without any physical material or component tests. Further, welding of the 10 mm thick extrusions gives a 10% degradation of the capacity in terms of ballistic limit velocity compared to the unaffected material.