An integrated (ICME) approach to multiscale modelling of the fabrication and joining of powder processed parts

基于金属粉末的生产方法，如HIP或增材层制造（ALM）的适用性受到无法以足够的精度定义工艺参数以提供工业生产所需质量的限制。同样，由于缺乏对相关合金系统中发生的气液相相互作用和固态相变影响的理解，部件制造所需的连接技术的实施受到了限制。基于实际试验和物理评估的传统解决方案既昂贵又耗时，而且对于能源和推进工业中遇到的长使用寿命来说是不可行的，而基于经验的现象学建模方法无法提供所需的保真度。为了满足这些工业需求，提出了一种多尺度建模方法，该方法将实验验证与材料建模的应用相结合，在捕获相关物理所需的短长度尺度上，与技术的发展一起，以一致的方式将预测的行为结合在更高长度尺度上，用于组件级模拟。多尺度模型集成将由许多组成部分组成，从焊接和增材制造中的短尺度流体流动和液/气相互作用的基于新多物理场的计算流体动力学计算开始。这些将提供孔隙度形成的数据，这些数据将与颗粒结构的元胞自动机预测相结合。将开发新的方法，将这些细尺度数据结合在基于有限元的晶体塑性框架中，以定义具有代表性的体积单元，用于模拟部件应力分析中的宏观行为。组件级仿真工作将建立在EPSRC Smith教授制造奖学金的基础上，通过利用在焊接施加的微观结构变化影响方面获得的知识，对高完整性焊接技术进行全寿命方法的研究。这些对焊缝在使用过程中的抗退化性和对裂纹的敏感性有深远的影响。从奖学金工作中获得的316L不锈钢的微观结构特征数据也将为模型验证提供基础。这个项目发展的一个关键部分将是扩展，从典型的单值确定性模型，到基于统计的材料特性和过程可变性的描述。这是一项具有挑战性的活动，但建模工具必须能够预测在真实材料中看到的散射。一个成功的解决方案不仅将产生新的科学，而且将明显导致概率寿命方法的发展，这些方法具有基于风险的决策输出，这对工业有明显的好处。这种方法为更好地了解现有英国核反应堆机组和任何长期结构性能重要的工业部门的组件和焊缝的使用性能提供了前景。在美国，类似的发展导致了一个被称为集成计算材料工程（ICME）的新领域。这是一种多学科的产品设计方法，具有巨大的经济潜力，ICME的成功实施将彻底改变组件的设计和制造方式。该提案将利用基于ICME的方法解决316L不锈钢HIPped和TIG焊接部件的工业演示的建模和设计挑战。由航空航天和能源行业的合作伙伴提供的演示将展示在不同市场部门可以实现的好处。拟议中的项目将是英国首次尝试将ICME工具用于大规模工业示范。

The applicability of metallic powder based production methods such as HIP or additive layer manufacturing (ALM) are restricted by an inability to define the process parameters with sufficient accuracy to provide the quality required for industrial production. Similarly the implementation of the joining technologies needed for component fabrication is limited by a lack of understanding of both the gas-liquid phase interactions and the effect of the solid state phase transformations that occur in the relevant alloy systems. Traditional solutions, based on practical trials and physical assessment, are both costly and time consuming and for the long service lives encountered in the energy and propulsion industries are not feasible while empirically based phenomenological modelling approaches cannot provide the required fidelity. To address these industrial needs a multiscale modelling approach is proposed which combines experimental validation with the application of materials modelling, at the short length scales required to capture the relevant physics, together with the development of techniques to incorporate the predicted behaviour in a consistent manner at higher length scales for application to component level simulations. The multiscale model integration will consist of a number of component parts commencing with new multiphysics based computational fluid dynamics calculations of the short length scale fluid flow and liquid/gas interactions in welding and additive manufacturing. These will provide data on porosity formation which will be combined with cellular automata predictions of grain structure. Novel methods will be developed to combine this fine scale data in a finite element based crystal plasticity framework to define representative volume elements for modelling the macroscopic behaviour in component stress analysis.The component level simulation work will build upon the EPSRC Manufacturing Fellowship of Prof Smith on a whole-life approach to high integrity welding technologies by utilising the knowledge gained on the effect of the microstructural changes imposed by welding. These have a profound influence on a weld's resistance to in-service degradation and upon its sensitivity to the presence of cracking. The microstructural characterisation data available on 316L stainess steel from the Fellowship work will also provide a basis for the model validation.A key part of the developments in this project will be the extension, from typical single value deterministic models, to statistically based descriptions of material properties and process variability. This is a challenging activity but it is essential that modelling tools become capable of predicting the scatter that is seen in real materials. A successful solution will not only generate novel science but will clearly lead to the development of probabilistic lifing methods with risk based outputs for decision making which have clear benefits for industry. This approach provides the prospect of a better understanding of in-service performance of components and welds in both the existing UK nuclear reactor fleet and in any industrial sector where long term structural performance is important.Similar developments in the US have led to a new field known as Integrated Computational Materials Engineering (ICME). This is a multi-disciplinary approach to product design that offers huge economic potential and the successful implementation of ICME will revolutionise the way components are being designed and manufactured. This proposal will address the modelling and design challenge using an ICME based approach on industrial demonstrators of 316L stainless steel HIPped and TIG welded parts. The demonstrators, supplied by the partners from the aerospace and energy industries, will show the benefits that can be achieved in different market sectors. The proposed programme will be the first attempt in the UK to use ICME tools on large industrial scale demonstrators.