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

向21世纪高价值制造业的下一步过渡需要开发创新工艺，以(i)减少周期时间和成本，从而最大限度地提高生产率和更高的盈利能力；（ii）提高性能和质量，同时减少对环境的影响。为了实现这一目标，现代制造业所需的发展和强化需要更广泛地使用更高的温度、力、变形和加载率。在实践中，建模和仿真工具的开发和应用是应对这些挑战的唯一可行方法，特别是对于新的变革性制造工艺。传统上，诸如轧制和锻造等工艺一直是新兴经济体的支柱，例如在印度，中国。这些具有低变形率的过程被很好地理解。拟议的研究涉及变形速率谱另一端的过程，其特征是异常高的幅度-这是创新的，潜在的变革性的，但鲜为人知。超声辅助加工等材料去除工艺和直线摩擦焊接等固态连接工艺以及新型精加工工艺都属于这一类；这些将在本项目中得到强调。在这种加载机制下，人们面临着重大挑战。首先，由于处理非常快，很难或不可能中断诊断目的；这一事实强调了数学建模对确定最佳实践和优化物理因素的分析的重要性。其次，实验验证——这是数学建模练习的重要部分——必须通过高速摄影/摄像等技术进行。第三，准确的建模要求材料的本构行为在代表过程的变形率下得到很好的理解。但对于镍基高温合金、钛和镁合金等新型、高等级合金系统来说，情况还不是这样。因此，需要对这类提出的新研究——例如，使用增强分离式霍普金森压力棒技术。最后，在高应变速率状态下，温度梯度显著；这些会造成很大的热应力，因此有可能出现开裂、断裂等。准确地对这些模型进行建模是一个重大的挑战，但如果要生产现实的制造模拟，就必须这样做。提出的研究解决了具有工业相关案例研究和应用的先进材料变革性制造过程模拟的具体挑战。为了有效地管理项目，工作方案分为七个工作包，包括(1)材料行为的建模；（ii）连续行为和过程区建模；（iii）材料特性；（iv）工艺特性和制造参数；(v)优化研究；工业反馈分析；管理和传播。

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.