MAST: Modelling of advanced materials for simulation of transformative manufacturing processes

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A transition to the next step in high-value manufacturing in the 21st century requires the development of innovative processes to (i) reduce cycle times and costs so that productivity and higher profitability are maximised, and (ii) enhance performance and quality whilst reducing environmental impact. To achieve this, the required development and intensification of modern manufacturing necessitates a broader use of higher temperatures, forces, deformations and loading rates. In practice, the development and application of modelling and simulation tools are the only practical way in which these challenges will be met, particularly for new transformative manufacturing processes. Traditionally, processes such as rolling and forging have been the mainstay of emerging economies, e.g. in India, China. These processes, with low deformation rates are well understood. The proposed research relates to processes at the other end of the deformation-rate spectrum characterised by exceptionally high magnitudes - which are innovative, potentially transformative and much less well understood. Material-removing processes such as ultrasonically-assisted machining and solid-state joining processes such as linear friction welding as well as novel finishing process are in this class; these will be emphasised in the present project. In this loading regime, one faces significant challenges. First, since processing is very fast it is difficult or impossible to interrupt for diagnostic purposes; this fact emphasises the importance of mathematical modelling for the analysis of the physical factors determining best practice and optimisation of it. Second, experimental validation - which is a vital part of the mathematical modelling exercise - must proceed by techniques such as high-speed photography/videography. Third, accurate modelling requires the constitutive behaviour of the material to be well understood at deformation rates representative of the process. This is not yet the case for novel, high grade alloy systems such as nickel-based superalloys, titanium and magnesium alloys, so that novel research of the type proposed - using an augmented split Hopkinson pressure bar technique, for example - is required. Finally, temperature gradients in the high strain-rate regime are significant; these cause large thermal stresses and therefore the possibility of cracking, fissuring etc. It is a significant challenge to model these accurately but this must be done if realistic manufacturing simulations are to be produced. The proposed research addresses specific challenges of process simulations for transformative manufacture with advanced materials with industrially-relevant case studies and applications. In order to manage the project effectively, the programme of work is split into seven work packages, covering modelling of (i) materials behaviour; (ii) modelling of continuum behaviour and process zone; (iii) materials characterisation; (iv) process characterisation & manufacturing parameters; (v) optimisation studies; (vi) analysis of industrial feedback and (vii) management and dissemination.