Effect of Changing Plastic Work on Macroscopic Properties

钛合金由于其能够承受恶劣的热环境和机械环境而被广泛用于制造航空发动机部件。最近对钛合金特性的了解表明，在制造过程中赋予合金的塑性功可能对材料性能产生长期影响。虽然这通常会影响整体性能（例如体积硬度），但新型制造和加工技术（例如增材制造和激光冲击喷丸）的进步已经显示出改变局部材料性能以实现组件所需性能的有希望的结果。本计画的目的是研究改变塑性功对钛合金宏观性质的影响。这项研究结合了实验研究和多尺度建模，将特定的微观结构特征与宏观弹塑性特性相关联，从而导致开发新的方法和工具，用于预测并最终通过各种制造和加工技术为这些合金规定所需的行为。实验将涉及对钛合金施加不同程度的严重塑性变形，然后对其进行广泛的机械测试，以探测应力状态，温度和应变速率对屈服和流动行为的影响。将通过试验前后的微观结构分析提供初始和最终缺陷状态以及应力松弛机制的详细信息。这些实验结果将用于连接晶体塑性体规模的连续强度模型。这些模型将扩展我们在组件级模拟方面的知识，并扩展多尺度建模工作流程。目前正在为镁开发类似的工作流程，这将作为本研究框架的基础。将创建目标钛合金的实验验证数值模型，并用于填充弹塑性各向异性连续体模型库。通过利用对塑性功效应的理解，这些模型可以在制造过程中选择性地分配给结构的不同区域，以优化下一代组件的性能。该研究项目得到了劳斯莱斯的支持，因为获得的知识和开发的方法将有助于该公司进一步了解塑性功变化的基本现象及其对改进发动机部件设计的影响。该项目也属于工程设计和制造技术的EPSRC研究领域的福尔斯，因为开发的方法将提高当前和未来产品的材料建模能力，并确定特定的加工路线，以实现复杂工程结构的微观结构优化。

Titanium alloys are the widely used to manufacture aero-engine components due to their capability to withstand harsh thermal and mechanical environments. Recent understanding developed on the characterisation of Titanium alloy has shown that plastic work imparted in the alloys during the manufacturing process can have long-lasting effects on the material properties. While this usually affects the global properties (e.g. the bulk hardness), the advancement of novel manufacturing and processing techniques, such as additive manufacturing and laser-shock peening, has shown promising results in altering local material properties to achieve the required performance in a component. The aim of this project is to investigate the effect of changing plastic work on the macroscopic properties of Titanium alloys. This research incorporates experimental investigations and multiscale modelling to correlate specific microstructural features to macroscopic elasto-plastic properties, which then leads to the development of new methods and tools for predicting and ultimately prescribing the desired behaviours to these alloys through various manufacturing and processing techniques. The experiments will involve applying varying degree of severe plastic deformation on Titanium alloys, which will then be subjected to a wide range of mechanical testing to probe the effects of stress-state, temperature and strain-rate on yield and flow behaviour. Details of the initial and final defect states and stress relaxation mechanisms will be provided by microstructural analysis prior to and after testing. These experimental results will then used to connect the crystal plasticity to bulk-scale continuum strength models. These models will expand our knowledge in component-level simulations and extend the multiscale modelling workflow. A similar workflow is currently being developed for Magnesium, which will act as the basis of the framework for this research to build upon. Experimentally-validated numerical models for the Titanium alloy of interest will be created and be used to populate the library of elasto-plastic anisotropic continuum models. By exploiting the understand of the effect of plastic work, these models can be selectively assigned to different regions of a structure during the manufacturing process to optimise the performance of next-generation components. This research project is supported by Rolls-Royce as the knowledge gained and the methods developed will aid the company in further understanding the underlying phenomena of changing plastic work and its implications for improving its engine component design. This project also falls within the EPSRC Research Areas of Engineering Design and Manufacturing Technologies as the developed methods will improve the material modelling capability for current and future products, as well as identify specific processing routes to achieve microstructural optimisation of complex engineering structures.