Collaborative Research: An Integrated Multiscale Modeling and Experimental Approach to High Cycle Fatigue Life Prediction

该合作项目的研究目标是采用紧密集成的建模/实验方法研究代表性工程合金（304奥氏体不锈钢、Inconel 718+镍基高温合金和Ti-6Al-4V合金）的高周疲劳失效。将丰富的时空有限元方法和多尺度疲劳损伤模型相结合，建立了一个计算框架。通过这种方法，将获得新的知识，通过研究的关键因素，如载荷循环，应力历史和三轴性，非线性耦合之间的负载，和复杂的几何形状，这是众所周知的严重影响疲劳破坏，一般不完全占在经验设计方法，正在实践中的今天。通过计算工作揭示的基本机制将通过现有的实验数据以及建议的高周疲劳试验进行验证和确认，其特征在于原位监测疲劳裂纹的萌生和扩展。此外，将进行微观结构表征，以建立所观察到的微观结构变形机制和建议的多尺度材料模型之间的映射。如果成功，该项目将在许多关键工程应用中的高周疲劳失效的基本机制上揭开新的一页。示例包括用于能源和电力应用的涡轮机、航空航天结构部件和高性能电子产品。该项目开发的多尺度仿真模型和实验技术也将引起其他研究人员的兴趣，他们正在研究更广泛的材料和设备的高周疲劳机制。所获得的高周疲劳研究成果将完全纳入本科/研究生课程。知识将通过网络手段，通过各种渠道向广大受众传播，包括毕业生、本科生、K-12和代表性不足的群体。

The research objective of this collaborative project is to investigate high cycle fatigue failure in representative engineering alloys (304 austenitic stainless steel, Inconel 718+ Ni-based superalloy and Ti-6Al-4V alloy) with a tightly integrated modeling/experimental approach. A computational framework will be established based on the integration of an enriched space-time finite element method and a multiscale fatigue damage model. With this approach, new knowledge will be gained through studies on key factors such as load cycles, stress history and triaxiality, nonlinear coupling among the loads, and complex geometry, which are known to critically influence the fatigue failure and generally not fully accounted for in the empirical design approaches that are being practiced today. The fundamental mechanisms revealed through the computational efforts will be verified and validated through existing experimental data as well as proposed high cycle fatigue tests featuring in-situ monitoring of fatigue crack initiation and propagation. Additionally, microstructural characterization will be performed to establish a map between the observed microstructural deformation mechanism and the proposed multiscale material model.If successful, this project will shed new night on the fundamental mechanisms that govern the high cycle fatigue failure in many critical engineering applications. Examples include turbines used for energy and power applications, aerospace structural components, and high-performance electronics. The multiscale simulation models and experimental techniques developed from this project will also be of interest to other researchers who are studying high cycle fatigue mechanism for a broader range of materials and devices. The acquired research results on the topic of high cycle fatigue will be fully incorporated into the undergraduate/graduate curricula. With a cyber-enabled approach, the knowledge will be disseminated through a variety of channels towards a wide range of audiences, including graduates, undergraduates, K-12 and underrepresented groups.