Fatigue Testing beyond Extremes

超越极限的疲劳测试

• 批准号: EP/T026529/2
• 负责人: Jicheng Gong
• 金额: $ 89.13万
• 依托单位: King's College London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FT026529%2F2
• 关键词: Fatigue; Testing; beyond; Extremes

Fatigue is the most pervasive failure mode that affects nearly all industrial sectors - including energy industries involving power plants, anemo-electric and tidal stream generators; transport vehicles and aircraft; national infrastructure such railway and bridges; military equipment from a blade in an engine to a whole ship; medical devices and human body implants. The economic cost of fracture has been enormous, approaching 4% of GDP, whereas 50-90% of all these mechanical failures are due to fatigue. Most fatigue failures are unexpected, and can lead to catastrophic consequences. In safety-critical sectors such as the aero-space and nuclear industries, there are ever increasing demands for better understanding of fatigue with respect to the microstructure of metallic components and the demanding environments that they are placed in.The ultra-small, ultra fast fatigue testing techniques I have created are able to make a breakthrough by addressing the classic needle in haystack problem in fatigue crack initiation (FCI) and short crack growth (SCG). Fatigue at these early stages is localized within a few hundred micro-meters. However, they account for more than 50% life in low cycle fatigue (LCF) and approximately 90% in the high cycle fatigue (HCF) regime, and contribute to the largest portion of scatter. My micro- and meso- cantilever techniques are capable of isolating FCI and SCG in selected microstructure features, allowing for the systematic exploration of slip evolution, slip band decohesion and short crack propagation in the context of an exquisitely well characterised volume of material. The ultra-fast testing rate up to 20 kHz means robust exploration can be achieved to 10^9 cycles and beyond, in hours in contrast to months or years demanded by the conventional method. This proposal, through further development of state-of-the-art extremely small and fast fatigue testing techniques, looks to radically change the technical scope of fatigue analysis by allowing environmental effects to be systematically explored at the levels of FCI and SCG and across the HCF and LCF regimes. In-situ ultrasonic fatigue testing rig will be installed in an advanced scanning electron microscope, enabling in-situ observation of the progression of HCF FCI and SCG at the resolution of ~ 1 nm. I will apply these cutting edge techniques to underpinning major fatigue issues in Ti and Ni alloys of technologically importance to the aero-engine industry and proton accelerators, specifically:(i) To achieve a breakthrough in mechanistic understanding of HCF FCI and SCG in titanium alloys with respect to the environments and deliver essential HCF FCI and SCG properties;(ii) To make groundbreaking study of fatigue in Alpha Case and dwelling fatigue in titanium alloys, which are major issues in aero-engine industry; (iii) To determine the effect of the heavy irradiation on HCF performance of Ti-alloys that will be used in the next generation proton accelerators; (iv) To achieve comprehensively understanding of the environmental effect on fatigue in single-crystal nickel superalloys that have the heterogeneous distribution of gamma' phase and element segregation;(v) To determine the HCF and LCF performance of the multi-functional coatings on the surface of a nickel turbo blade in the context of atmosphere, temperature and pre-corrosion treatment.A Ultrasonic Fatigue Testing Centre will be established to satisfy the frequent HCF assessment requests from the industry. The new functions developed on the ultrasonic fatigue testing rig in this project will be transferred to the national lab at Culham to update the bespoke rig in a 'hot cell', for study of active materials in support of fission and fusion innovation.

疲劳是影响几乎所有工业部门的最普遍的故障模式，包括涉及发电厂、风电和潮汐流发电机的能源行业；运输车辆和飞机；铁路、桥梁等国家基础设施；从发动机叶片到整艘船的军事装备；医疗设备和人体植入物。断裂的经济成本是巨大的，接近GDP的4%，而所有这些机械故障中有50-90%是由于疲劳造成的。大多数疲劳失效都是意料之外的，并可能导致灾难性的后果。在航空航天和核工业等安全关键部门，人们越来越需要更好地了解金属部件的微观结构及其所处的苛刻环境的疲劳。我所创建的超小型、超快速疲劳测试技术能够通过解决疲劳裂纹萌生（FCI）和短裂纹扩展（SCG）中的经典“大海捞针”问题取得突破。这些早期阶段的疲劳局限在几百微米范围内。然而，它们在低周疲劳（LCF）状态下占50%以上的寿命，在高周疲劳（HCF）状态下约占90%的寿命，并且是造成散射的最大部分。我的微悬臂和中观悬臂技术能够在选定的微观结构特征中分离出FCI和SCG，从而允许系统地探索滑移演化、滑移带脱黏和短裂纹扩展，这些都是在材料的精细特征体积的背景下进行的。高达20 kHz的超快测试速率意味着可以在数小时内实现10^9个周期甚至更多的稳健勘探，而传统方法则需要数月或数年。该提案通过进一步发展最先进的小型和快速疲劳测试技术，通过允许系统地探索FCI和SCG水平以及HCF和LCF制度的环境影响，从根本上改变疲劳分析的技术范围。在先进的扫描电子显微镜上安装原位超声疲劳试验台，可以在~ 1 nm分辨率下对HCF FCI和SCG的进展进行现场观察。我将运用这些前沿技术来解决对航空发动机工业和质子加速器具有重要技术意义的钛和镍合金的主要疲劳问题，具体而言：(I)在对钛合金中HCF FCI和SCG的机制理解方面取得突破，并提供基本的HCF FCI和SCG性能；（二）开创性地研究了航空发动机工业中的重大问题——阿尔法壳体疲劳和钛合金停留疲劳；确定重辐照对将用于下一代质子加速器的钛合金的HCF性能的影响；(4)全面了解具有γ′相不均匀分布和元素偏析的单晶镍高温合金的环境对疲劳的影响；(v)确定镍涡轮叶片表面多功能涂层在大气、温度和预腐蚀处理条件下的HCF和LCF性能。将建立一个超声疲劳测试中心，以满足业界频繁的HCF评估要求。在这个项目中，超声波疲劳试验台开发的新功能将转移到Culham的国家实验室，在“热室”中更新定制的试验台，用于研究支持裂变和聚变创新的活性材料。