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

该提案建立在现有合作的基础上，该合作的重点是通过详细的实验和模拟，在从铝到哈氏合金x等传统制造金属的板和梁中，实现对高达750K和800 Hz的热声激励下材料结构响应的多尺度理解。在材料微观结构中，变形倾向于集中在与宏观均匀分析预测的位置不同的较大的寡晶颗粒中（Carroll等人，Int.）。[j] .疲劳，57:140-150,2013)，这表明微观结构的不均匀性会导致预测失效的重大和服务关键错误。进一步的实验室规模实验，使用宽带热声激励期间测量的表面变形图，证实了当不均匀加热产生热屈曲时存在模式跳跃和转移（Lopez-Alba et al .， J. Sound & Vibration 439:241-250, 2019）。考虑到这一点，研究小组将这些测试扩展到组件规模，建立了简单组件热声激励耦合模型的定量验证程序（Berke et al, Exptl）。动力机械。生态学报，56(2):231-243,2016)。为此，该团队开发了两种独特的实验装置：在伊利诺伊州，用于优惠券的局部加热和模态激励；在利物浦，提供21kW的空间分布加热，同时对小部件施加随机宽带激励。这两款钻机都具有实时、现场温度和位移测量能力。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）方面具有相应的互补专业知识。建议利用这些发现，设施和专业知识来了解增材制造在苛刻环境中受极端热机械激励的部件生产中的潜力。这种类型的结构可能会少量生产，因此可以考虑增材制造；然而，温度和机械载荷的极端条件使其成为任何材料的具有挑战性的应用。此类组件的成功设计、制造和服务部署需要了解材料结构对载荷的多尺度响应及其随组件从初始状态到振动到可检测的非临界损伤的演变过程。对于减法制造的金属，这些反应在基本层面上得到了理解；然而，无论是在室温下，对增材制造金属的这些材料-结构相互作用的基本理解都非常有限(Attar等人，IJ Mach。工具和操作。中国科学：地球科学，2018,(3):85-102。Eng。生态学报，2018,37(4):536-546)。添加,马努。， 1-8, 2018)。据推测，由于独特的微观结构包含先前研究过的较大的寡晶颗粒，其制造的复杂的热力学历史和显著残余应力的存在，增材制造的金属在极端热声载荷下的响应将显著不同于减法制造的金属，特别是在缺陷驱动的过程中，如失效。该提案通过增加Sutcliffe （Renishaw AMPD研发总监，2018年RAe银奖获得者，研究金属增材制造超过20年）提供的增材制造专业知识和设施，扩展了Lambros和Patterson的研究，他拥有无与伦比的最新增材制造技术。

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.