Full-field elasto-plasticity in dissimilar welded joins

Design codes for weld properties are over-conservative due to uncertainty in performance. Importantly, standard tests are not suitable for the complex stress states involved and the highly variable geometry of joins, e.g. T-joins. This is a spatially complex problem that lends itself to spatially-resolved full-field measurements of deformation. However, we urgently require numerical methods to interpret the experimental data for useful parameter extraction to inform component design. The purpose of this project is to develop integrated experimental-modelling methods with Digital Image Correlation (DIC) and the Virtual Fields Method (VFM) for extracting the full field deformation behaviour of fusion-relevant dissimilar joins. This will be achieved through the development of existing numerical methods to extract elasto-plastic constitutive parameters and true stress-strain data from varied dissimilar join geometry with controlled stress concentrators to reflect tokomak engineering-relevant situations.

This PhD project will push VFM parameterisation towards the automatic detection of deformation zones within dissimilar welded joins. In comparison to finite element analyses, the VFM is up to 125 times faster as it requires no forward modelling, iteratively solving the weak form of the equilibrium equations for non-linear problems.