| Abstract |
The objective of DEEPWELD is to develop a multi-physics multi-scale numerical tool for simulating the Friction Stir Welding process, that will be able to obtain accurate predictions of residual stresses, weld properties and tool loads. The new tool will be a large step forward compared to current thermo-mechanical solutions, indeed the latter depend on well calibrated heat fluxes used as energy input in the model. These heat fluxes must be obtained by measurements of data during experiments. This prevents optimisation of the process parameters and real usage of the FSW simulation system in a design environment for predictive simulation of the behaviour of parts.
A novel approach will be followed in DEEPWELD. A detailed simulation of the material flow around the tool will be coupled to a simulation of the complete welding process. The software developments forming the core of DEEPWELD will be focussed on:
" a material flow solver capable of simulating the material flow around the tool;
" coupling of the material flow solver to existing but modified industrial FE codes; this will allow the use of all existing features of the industrial codes to handle industrial applications and ease exploitation of the new tool in the industrial environment.
" since the temperature will strongly affect the rheology of the material, a material model (metallurgy) capable of dealing with the large variations in material properties throughout the weld region will be developed and implemented;
" furthermore, an appropriate friction law which describes the behaviour at the interface between tool and weld material needs to be implemented.
DEEPWELD also involves a strong experimental part. Experiments will be conducted at two levels to obtain on one hand the required input data for the simulation such as accurate reologhical material properties, improved metallurgy models, friction models, material flow visualization and on the other hand detailed validation on industrial real-life applications. Experiments on 2XXX and 7XXX alloys will be conducted on conventional and bobbin tool technology machines. Aeronautical coupons will be experimentally and virtually welded and structural response tests will be carried out to further validate predictions of the numerical tool. Guidance for certification of welded parts will be drafted.
DEEPWELD objectives are a step forward compared the simulation activities in former fp5 WAFS project. Since several partners of DEEPWELD were involved in WAFS, knowledge will be bridged into DEEPWELD hence reducing risks in R&D activities. DEEPWELD can also contribute to fp6 WEL-AIR project completely dedicated to experimental usage of FSW and other welding techniques. Dissemination of DEEPWELD results to other EU (EuroStir, etc) or national R&D projects in FSW will be performed. |
