Finite element analysis of plastic failure in heat-affected zone of welded aluminium connections

Finite element analyses of plastic failure in the heat-affected zone of a generic welded aluminium connection are presented. The analyses include process history through multi-scale modelling. The heterogeneous material properties of the heat-affected zone are calculated using welding simulations to obtain the temperature history as input to coupled precipitation, yield strength and work-hardening models. Thermal history-dependent material parameters are mapped as field variables onto the finite element model to account for their spatial variation inside the heat-affected zone. The welded connection is modelled using shell elements, solid elements and cohesive-zone elements. Convergence studies show that very small elements are needed (much less than the plate thickness) to resolve the large strain gradients within the HAZ and to obtain converged solutions. Non-local regularization is vital in shell element analyses to obtain accurate estimates of the ductility of the welded connection. Two methods for estimating the ductility in the welded aluminium connection with coarser meshes are proposed.