Numerical simulation of crack extension in aluminium welds

Experimental and numerical investigations on stable crack extension of aluminium-laser beam welds (6XXX-series) are presented. Experiments are carried out on C(T)-specimens. Initial cracks are assumed in the base material and in the fusion zone. Local mechanical quantities are determined by micro-flat tensile specimen, taken from the weld nugget, the heat affected zone and the base material. Finite element calculations together with an evolution strategy are used in order to determine parameters of the Gurson-Tvergaard-Needleman model (GTN-model) used for the simulations. Crack propagation in the base material as well as in the undermatched fusion zone is described in terms of fracture resistance curves. It is found that the GTN-model is able to simulate ductile crack growth in the base material and the fusion zone using non-standard model parameters. (C) 2003 Elsevier B.V. All rights reserved.