Predictive Modelling for Incremental Cold Flow Forming: An integrated framework for fundamental understanding and process optimisation

增量冷流成形（ICFF）是一种用于生产高质量、旋转对称、中空工程部件的金属成形工艺，广泛应用于航空航天、汽车和石油天然气行业。在ICFF中，圆柱形预制件附着在旋转芯轴上，轴向平移辊对外表面施加压缩。这导致挤压的工件材料通过显著的塑性变形。由于增加的过程-滚轮在任何时候都与工件外表面的一小块区域接触-材料的挤压发生的力明显低于传统成型工艺所需的力。因此，ICFF非常适合于高强度、不易变形的材料。该过程是“冷的”，因为在工件和滚轮之间发生接触的地方应用了冷却剂。在材料的再结晶温度以下发生明显的变形。结果，冷加工硬化导致最终产品的强度、刚度和硬度增加。与传统的锻造和深拉深相比，ICFF的一个显著优势是它使工程师能够灵活地设计不同尺寸的复杂部件。与标准制造路线相比，ICFF可以通过提高产量、减少生产时间和改善材料性能来节省大量成本。此外，ICFF允许快速原型来支持虚拟产品设计，从而降低开发成本并推动创新。尽管ICFF与传统方法相比具有显著优势，但仍存在相当大的挑战。在广泛采用之前，必须克服这些问题。首先是过程的可重复性和可靠性不令人满意；它可能是不稳定的，材料可能会发生故障。控制复杂的ICFF过程具有挑战性。这是由于大量的工艺参数和高度非线性的变形性质。关键的是，目前还没有准确和可靠的模型来阐明在ICFF期间发生的基本物理机制。如果没有这样的模型，将ICFF应用于新产品和新材料将需要昂贵的组件规模的试错测试，并且仍然是一门艺术，而不是一门科学。先进成形研究中心（AFRC）和格拉斯哥计算工程中心（GCEC）之间的这项合作研究计划的主要目的是开发一个工程设计框架来模拟ICFF。了解材料对ICFF施加的加载机制的响应是模型开发的关键组成部分。为此，我们将在AFRC进行详细的材料特性研究。工件上的载荷将使用高度仪器化的研究专用ICFF机器进行测量。此外，将开发用于ICFF的材料表征程序，使工业界能够测试用于ICFF的新材料，从而减少对昂贵的ICFF试验的需求。计算模型将建立在MoFEM提供的现有框架上，并大大扩展该框架- MoFEM是GCEC开发的最先进的通用有限元库。该模型将考虑到ICFF的所有关键特征，包括显著变形、旋转部件之间的接触、热效应和残余应力。这些过程的高度非线性和耦合性质使得建模具有挑战性。MoFEM的模块化特性使我们能够专注于为ICFF设计新的、高效的和健壮的数值方法，而不是开发库的核心。该模型精确模拟一系列ICFF应用的能力将通过在AFRC进行的组件规模测试来证明。最后，模型的预测能力将通过数值优化工艺参数来评估，以实现所需的净形状。

Incremental cold flow forming (ICFF) is a metal forming process for the production of high-quality, rotationally-symmetric, hollow engineering components as widely utilised by the aerospace, automotive and oil & gas sectors. In ICFF, a cylindrical preform is attached to a rotating mandrel and axially-translating rollers apply compression to the outer surface. This leads to extrusion of the workpiece material via significant plastic deformation. As a result of the incremental process - rollers are in contact with a small area of the exterior surface of the workpiece at any one time - the extrusion of the material occurs with significantly lower force than required for conventional forming processes. ICFF is thus well suited to high-strength, hard-to-deform materials. The process is "cold" as a coolant is applied where contact occurs between the workpiece and the roller. The deformation occurs significantly below the material's recrystallisation temperature. As a result, cold work hardening occurs leading to increased strength, stiffness and hardness of the final product. A significant advantage of ICFF over conventional forging and deep drawing is the flexibility it gives engineers to design complex components of varying size. ICFF can result in considerable cost savings via improved yields, reduced production times and improved material properties, as compared to standard manufacturing routes. Furthermore, ICFF allows for rapid prototyping to support virtual product design, thereby reducing development cost and driving innovation.Despite the significant advantages that ICFF has over conventional methods, considerable challenges remain. These must be overcome prior to its widespread adoption. Foremost is the unsatisfactory repeatability and reliability of the process; it can be unstable and failure of the material can occur. Controlling the complex ICFF process is challenging. This is compounded by the large number of process parameters and the highly nonlinear nature of the deformation. Critically, there is currently no accurate and robust model to elucidate the fundamental physical mechanisms that occur during ICFF. Without such a model, the application of ICFF to new products and materials will require costly trial-and-error component-scale testing and remain an art as opposed to a science. The primary aim of this collaborative research proposal between the Advanced Forming Research Centre (AFRC) and the Glasgow Computational Engineering Centre (GCEC) is to develop an engineering design framework to model ICFF. Understanding the response of materials to the loading regime imposed by ICFF is a key component of the model development. To this end, we will undertake a detailed materials characterisation study at the AFRC. The loading on the workpiece will be measured using a highly-instrumented, research-dedicated ICFF machine. In addition, a materials characterisation procedure for ICFF will be developed that will allow industry to test new materials for ICFF thereby reducing the need for costly ICFF trials.The computational model will build upon and significantly extend the existing framework provided by MoFEM - a state-of-the-art, general purpose finite element library developed within the GCEC. The model will account for all key features of ICFF, including significant deformations, contact between rotating parts, thermal effects and residual stresses. The highly non-linear and coupled nature of these processes makes modelling challenging. The modular nature of MoFEM allows us to focus on designing new, efficient and robust numerical methods for ICFF rather than developing the core of the library. The ability of the model to accurately simulate a range of ICFF applications will be demonstrated using component scale testing conducted at the AFRC. Finally the predictive capabilities of the model will be assessed by numerically optimising the process parameters to achieve a desired net shape.