CMMI-EPSRC: Thermoacoustic response of Additively Manufactured metals: A multi-scale study from grain to component scales

该建议建立在现有合作的基础上，该合作侧重于通过在从铝到Hastelloy X的常规制造金属的板和梁中使用详细的实验和模拟来实现对高达750K和800赫兹的热声激励的材料结构响应的多尺度理解。结果显示，在微观尺度上，变形倾向于集中在材料微结构中的较大晶体中，位置与宏观尺度均匀分析预测的位置不同(Carroll等，Int。进一步的实验室规模实验，使用在宽带热声激励过程中测量的表面形变图，证实了当非均匀加热产生热屈曲时，存在模式跳跃和移位(Lopez-Alba等，J.Sound&Vision439：241-250,2019)。考虑到这一点，研究小组将这些测试扩展到组件规模，为简单组件的热声激发耦合模型建立了定量验证程序(Berke等人，Exptl。机械，56(2)：231-243,2016)。为此，该团队开发了两种独特的实验设备：在伊利诺伊州，用于局部加热和优惠券的模式激励；在利物浦，在21kW的空间分布加热，同时对小部件施加随机宽带激励。这两个钻井平台都具有实时、全场温度和位移测量能力。相应地，Lambros和Patterson在极端载荷下材料的多尺度力学(Lambros)和结构响应的测量、模拟和验证(Patterson)方面具有互补的专业知识。建议利用这些发现、设施和专业知识来了解在苛刻环境中受到极端热机械激励的部件生产中添加制造的潜力。这种类型的结构很可能是小批量生产的，因此适合考虑添加制造；然而，极端的温度和机械加载条件使其对任何材料的应用都具有挑战性。此类部件的成功设计、制造和服务部署需要了解加载的多尺度材料-结构响应及其随部件从初始状态到摇摆到开始可检测到的非关键损伤的过程的演变。对于减法制造的金属，这些反应是在基本水平上理解的；然而，对于加法制造的金属，在任何一种室温下，对这些材料-结构相互作用的基本了解都非常有限(Attar等人，IJ Mach。工具与制造，133：85-102,2018，Foehring等人，Mat.SCI。英语。A，724：536-546,2018)或高温(Roberts等人，进步)。添加。马努，2018年1-8)。由于含有先前所研究的较大的寡晶的独特微观结构，其制造的复杂的热机械历史以及显著的残余应力的存在，人们假设添加加工的金属在极端热声载荷下的响应将显著不同于减法加工的金属，特别是在缺陷驱动的过程中，例如失效。这项建议扩展了Lambros和Patterson的研究范围，增加了Sutcliffe(雷尼绍AMPD研发总监，RAE Silver Medallist 2018年研究金属添加剂制造20多年)提供的添加剂制造专业知识和设施，他拥有无与伦比的最新添加剂制造技术。

The proposal builds on an existing collaboration which has focussed on achieving a multi-scale understanding of the material-structure response to thermoacoustic excitation at up to 750K and 800 Hz using detailed experiments and simulations, in plates and beams of conventionally-manufactured metals, ranging from aluminium to Hastelloy X. Results have shown, at a microscale, a tendency for deformation to concentrate in the larger grains of oligocrystal within the material microstructure at locations disparate from where macroscale homogeneous analysis predicts (Carroll et al., Int. J. Fatigue, 57: 140-150, 2013), demonstrating that non-uniformity in the microstructure can lead to significant and service critical errors in predicting failure.Further laboratory-scale experiments, using maps of surface deformation measured during broadband thermoacoustic excitation, have confirmed the presence of mode jumping and shifting when non-uniform heating generates thermal buckling (Lopez-Alba et al, J. Sound & Vibration 439:241-250, 2019). With this in mind, the research team scaled these tests to component scale, establishing quantitative validation procedures for coupled models of thermoacoustic excitation of simple components (Berke et al, Exptl. Mech., 56(2):231-243, 2016). In doing so, the team developed two unique pieces of experimental apparatus: in Illinois, for localised heating and modal excitation of coupons; and in Liverpool, to deliver spatially distributed heating at 21kW while simultaneously applying random broadband excitation to small components. Both rigs have real-time, full-field temperature and displacement measurement capability. Lambros and Patterson have correspondingly complementary expertise in multi-scale mechanics of materials under extreme loading (Lambros) and in measurement, simulation and validation of structural responses (Patterson).It is proposed to exploit these findings, facilities and expertise to understand the potential for additive manufacturing in the production of components subject to extreme thermomechanical excitation in demanding environments. It is likely that this type of structure will be produced in small quantities rendering it appropriate to consider additive manufacturing; however, the extreme conditions of temperature and mechanical loading make it a challenging application for any material. Successful design, manufacture and service deployment of such components requires an understanding of the multi-scale material-structure response to loading and its evolution with a component's progression from its virgin state through shake-down towards initiation of detectable non-critical damage. These responses are understood at a fundamental level for subtractively-manufactured metals; however, there is very limited fundamental understanding of these material-structural interactions for additively-manufactured metals, at either room temperature (Attar et al, IJ Mach. Tools & Manu., 133: 85-102, 2018, Foehring et al, Mat. Sci. Eng. A, 724: 536-546, 2018) or elevated temperatures (Roberts et al, Progress. Add. Manu., 1-8, 2018). It is hypothesized, because of the unique microstructure containing the previously studied larger grains of oligocrystal, the complex thermomechanical history of their manufacture and the presence of significant residual stresses, that the response of additively-manufactured metals under extreme thermoacoustic loading will be significantly different from their subtractively-manufactured counterparts, especially in defect-driven processes such as failure. This proposal extends the research of Lambros and Patterson by adding the additive manufacturing expertise and facilities provided by Sutcliffe (R&D Director at Renishaw AMPD, RAe Silver Medallist 2018 with over 20 years researching metal additive manufacturing) who has unparalleled access to the latest additive manufacturing technology.