Finite element modelling of welded aluminium members subjected to four-point bending

Finite element analyses are performed to predict the structural behaviour of welded and un-welded I-section aluminium members subjected to four-point bending. A modelling procedure using shell elements is established, where careful modelling of the inhomogeneous material properties due to welding is an important ingredient. A material model comprising anisotropic plasticity and ductile fracture is adopted. The yield function and work hardening parameters for the heat-affected zone, weld and base material are determined based on material tests and experimental data available in the literature. The numerical simulations comprise explicit analyses for a basic, relatively coarse mesh and implicit analyses for the same basic mesh and a refined mesh. Simulations are performed with perfect and imperfect geometries, since some beams fail by local buckling. The numerical results are compared with existing experimental data, and, in general, good agreement with the experimental results is obtained. However, the solutions are found to be mesh dependent for members failing by strain localisation and fracture in the tension flange.