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DEEPWELD
Detailed Multi-Physics Modelling of Friction Stir Welding

Background

DEEPWELD contributes to strengthening the competitiveness of the aeronautical industry in Europe. Friction stir welding (FSW) is a new technique that could revolutionise the way aircraft are built by replacing riveting with welding. The benefits of FSW include the ability to join materials that are difficult to fusion weld. It is a simple, robust process that involves no consumables. When handled properly, FSW results in a defect-free weld with superior properties. However, there is still a lack of knowledge on its applicability to aircraft structures. Although there is still a significant need for experiments, an advanced simulation tool is required to understand further the effect of the various welding parameters on the properties of the welds.

Project objectives

The overall goal of DEEPWELD is the development of a new multi-physics and multi-scale numerical tool for the accurate modelling of the friction stir welding process. This tool will help shorten the design cycle and decrease cost by reducing the number of experimental prototypes, replacing them with virtual prototypes. The DEEPWELD software will be equipped with a thermo-fluid module in order to simulate the important material flow around the FSW tool and an advanced metallurgy model in order to predict the evolution of microstructures. Specifically instrumented experiments will be conducted in order to define accurate thermally varying friction laws, material constitutive laws and data in order to validate the new numerical tool.

FSW experiment at UCL
FSW experiment at UCL

Description of the work

The work is organised into four technical Work Packages:

Work Package 1: Detailed specifications of industrial target applications: The development of a numerical tool to simulate the FSW process, within the DEEPWELD consortium, will be carried out following specifications of the industrial end-users. This Work Package defines these specifications in terms of materials, applications, performance, software and experiments.

Work Package 2: Physics and Metallurgy: The first objective is to provide quantitative information to be introduced as input in the numerical codes to be developed in the DEEPWELD Project. The second objective is to provide sufficient information for a better understanding of the physical phenomena occurring during FSW. This is required to select appropriate modelling assumptions for the different models or modules (thermo-fluid, thermo-mechanical, and metallurgical).

Work Package 3: Multi-physics simulation tool development: Development of a general, numerical tool incorporating the coupling of the following fields: mechanical, thermal, metallurgy and flow calculation. The development of this general and multi-physics model will allow for predictive FSW simulations by: 1) eliminating the equivalent heat flux determined from experiments and replacing it by a thermo-fluid calculation, which will predict the amount of heat generated through plastic work and friction; 2) taking into account the changes in mechanical properties due to transformations in the micro-structure of the material.

Work Package 4: Validation and Applications: The objectives of this Work Package are: 1) an experimental validation campaign with a wide range of operating conditions; 2) a welding parameters optimisation in order to maximise the quality of the welds; 3) an application to the coupons’ representative of industrial applications; 4) a structural response and certification to provide a quality criterion for the optimisation analysis.

Expected results

The expected result of DEEPWELD is a multi-physics and multi-scale simulation tool for the modelling of friction stir welding, able to achieve, among other things, accurate predictions of residual stresses, distortions, weld properties and tool loads.

Modelling of FSW
Modelling of FSW

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