Crash assessment of welded aluminium structures

In order to investigate the deformation and failure behaviour of welded aluminium joints and to validate the appropriate computational procedures under consideration of welding, residual stresses, experimental tests and numerical investigations have been performed. For the investigations, the age-hardened aluminium alloys AW6060 (AlMgSi) and AW7003 (AlZn6Mg0.8Zr) and their welds were chosen. As a result of the static and dynamic materials and component tests, the failure takes place in the weld and in the region of the fusion line due to the lower yield strength of the weld compared to the base material. The residual stresses obtained by a weld simulation were taken into account as initial conditions for a subsequent crash simulation. As a result, the influence of the welding residual stresses on the failure under crash loading is negligible. For the computational simulation of tensile and shear failure, a failure curve consisting of a combination of the Gurson model and the strain criterion of Johnson-Cook was qualified as a suitable failure model. To describe the failure of the weld, a simplified approach based on a constant lower bound failure strain also describes the test results quiet well.