Through Process Modelling of Welded Aluminium Structures
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This thesis aims to evaluate the accuracy, efficiency and robustness of a ‘Through Process Modelling’ concept tailored for analysis of the structural behaviour of welded aluminium structures. In short, the modelling concept relies upon the coupling of a welding simulation tool (WELDSIM), a microstructure model (NaMo) and a non-linear mechanical model (LS-DYNA). An experimental database addressing the capacity and ductility of simple welded joints of 6xxx and 7xxx alloys have been established. The experimental database includes results from studies on butt-welded specimens of aluminium alloy AA6005, AA6060, AA6061, AA7046 and AA7108. Two tempers; T4 and T6 prior to welding were investigated and the subsequent effects of natural ageing (NA) and post weld heat treatment (PWHT) were assessed. Cross-weld tensile tests were carried out with digital image correlation (DIC) to record the inhomogeneous strain field in these specimens. Variations of the mechanical properties of the material in the vicinity of the weld were further studied by hardness measurements. Uniaxial tensile tests were carried out to document and compare properties of unwelded and welded test specimens in the various conditions. Numerical investigations are carried out based on WELDSIM, NaMo and LS-DYNA for the AA6005, AA6060 and AA6061 alloys. The results are compared with the experimental data to identify present capability and limitations of the modelling approach.