CMMI-EPSRC: Quantitative Characterization of Mission Critical Microstructures of Engineering Metals with Diffusive Ultrasound

该奖项由美国国家科学基金会工程局- UKRI工程与物理科学研究委员会领导机构（ENG-EPSRC）资助，这是美国国家科学基金会与英国研究与创新（UKRI）工程与物理科学研究委员会（EPSRC）之间的合作征集。它将资助能够可靠地保证安全关键金属部件的研究，例如用于航空航天和核能工业的金属部件，从而促进科学进步，促进国家繁荣和福利。在金属零件制造过程中发生的热机械过程会产生决定强度、疲劳寿命、蠕变和耐腐蚀性的晶粒微观结构。在生产过程中仔细控制这些微观结构，并在组件完成后对其进行非破坏性表征是至关重要的。虽然超声波技术是获取材料内部特性的唯一实用手段，但它的工业用途非常有限，因为根据这种微观结构准确解释超声波信号仍然是一个未解决的问题。在精心准备后，依赖于对牺牲样品进行破坏性测试的替代技术被认为是不充分的，例如飞机发动机的故障就证明了这一点。该项目将通过提出一种新的方法来解释由于微观结构纹理和不均匀性引起的超声波散射，从而克服这些缺点，这可能会彻底改变在整个生产和服务中，在高温和复杂形状下使用非破坏性，非接触式超声波表征的方法。这种能力将支持新的先进制造工艺的发展，其对复杂几何形状的质量控制和保证的重要需求目前仅部分得到满足。与伦敦帝国理工学院的博兰博士合作，将提供国际研究交流和博士后科学家培训的机会，以及通过英国无损评估研究中心促进行业推广的途径。本研究旨在为超声漫射波场方法的发展做出基础性贡献，该方法能够对工程金属的关键任务微观结构进行体积表征。它将通过设计和校准实验转导机制和信号处理技术来实现这一目标，这些技术可以从不同样品几何形状的漫射波场中提取完整的格林张量，并将扩散率、衰减和散射的特性与微结构相关的特性联系起来。在此基础上，结合辐射传递理论推导出一般的多重散射理论，以解释纹理和微观结构对相干波的影响，并描述非相干波的扩散。这种波扩散的计算模型将根据实验结果进行验证，并用于构建漫射波场与材料微观结构之间定量联系的知识库。最后，将开发一种鲁棒的反演方法，从漫射波场数据中推导出关键的微观结构特性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded through the NSF Directorate for Engineering - UKRI Engineering and Physical Sciences Research Council Lead Agency (ENG-EPSRC) Opportunity, a collaborative solicitation between NSF and the Engineering and Physical Sciences Research Council (EPSRC) of United Kingdom Research and Innovation (UKRI). It will fund research that enables reliable assurance of safety-critical metal components, for example those used in the aerospace and nuclear power industries, thereby promoting the progress of science, and advancing the national prosperity and welfare. Thermomechanical processes that occur during manufacturing of metal parts result in grain microstructures that dictate strength, fatigue life, and creep and corrosion resistance. It is essential that these microstructures be carefully controlled during production and non-destructively characterized once a component is finished. Although ultrasound technology is the only practical means to access internal material properties, it has seen very limited industrial usage, as accurate interpretation of ultrasonic signals in terms of such microstructure remains an unsolved problem. Alternative techniques that rely on destructive testing of sacrificial samples after elaborate preparation are recognized as inadequate, as evidenced for example by failures of aircraft engines. This project will overcome these shortcomings by advancing a new method of interpreting ultrasonic wave scattering due to microstructural texture and inhomogeneities, potentially revolutionizing the use of non-destructive, contactless, ultrasonic characterization throughout production and in service, at elevated temperatures and on complex shapes. This capability will support the growth of new advanced manufacturing processes, whose vital need of quality control and assurance on complex geometries is currently only partially met. Collaboration with Dr. Bo Lan of Imperial College London will provide opportunities for international research exchange and training of postdoctoral scientists, as well as routes for industry outreach facilitated through the United Kingdom Research Centre in Nondestructive Evaluation.This research aims to make fundamental contributions to the development of an ultrasonic diffuse wave field method that enables volumetric characterization of mission critical microstructure of engineering metals. It will achieve this objective by designing and calibrating experimental transduction mechanisms and signal processing techniques for extracting the full Green’s tensor from the diffuse wave field on different sample geometries, and relating properties of diffusivity, attenuation, and scattering to microstructure-related properties. Further, a general multiple scattering theory will be derived in combination with radiative transfer theory, to account for the effects of texture and microstructures on coherent waves and to describe the incoherent wave diffusion. Computational models of such wave diffusion will be validated against experimental results and used to construct a knowledge database of quantitative linkages between the diffuse wave field and material microstructures. Finally, a robust inversion method will be developed for deducing critical microstructural properties from the diffuse wave field data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.