Modelling of microstructure-sensitive short fatigue crack propagation in Zircaloy-4: influence of microstructure, hydrides, and irradiation

锆-4合金的疲劳裂纹扩展速率和裂纹路径对微观结构高度敏感，并依赖于织构。这项工作的目的是获得这些微观结构的影响机制的理解。晶体塑性有限元模拟与扩展有限元法和存储能量密度（SED）断裂准则被用来模拟裂纹扩展的多晶微观结构与实验数据进行比较。一个新的分析解决方案FCG率的发展，促进快速估计。该模型是基于SED断裂准则，但与经典断裂力学，使裂纹尖端SED计算在更高的速率。正在进行的其他工作旨在捕获辐照对短FCG速率的影响。在裂纹存在的情况下，正在研究位错通道清除。附加的实验工作旨在了解锆-4合金中的氧化物对短FCG的影响。一系列研究中的第一项已经开始。最后，将开展研究，将以前的工作联系起来。第一个目标将是模拟前面提到的实验纳入δ-氢化物相。第二个目标将是将辐射损伤模型的理论评估的辐照损伤的锆-4合金。

Rates of fatigue crack growth (FCG) and crack paths in Zircaloy-4 are highly microstructurally sensitive and dependent upon texture. This work is aimed at gaining mechanistic understanding of these microstructural effects. Crystal plasticity finite element modelling with the eXtended Finite Element Method and a stored energy density (SED) fracture criterion is used to simulate crack propagation in polycrystalline microstructures for comparison with experimental data. A new analytic solution for FCG rate is developed, facilitating rapid estimates. The model is based on a SED fracture criterion but is linked with classical fracture mechanics, enabling crack tip SED calculations at higher rates. Other work which is underway is aimed at capturing irradiation effects on short FCG rate. Dislocation channel clearing is being investigated in the presence of a crack. Additional experimental work is aimed at understanding the influence of hydrides on short FCG in Zircaloy-4. The first of a series of studies has begun. Lastly, studies will be carried out which will link previous work. The first aim will be to simulate previously mentioned experiments from incorporating the delta-hydride phase. The second aim will then be to incorporate the irradiation damage model for a theoretical assessment of irradiation damage on hydrided Zircaloy-4.