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

锆合金4的疲劳裂纹扩展速率（FCG）和裂纹路径具有高度的微观结构敏感性和依赖于织构。这项工作的目的是获得这些微观结构效应的机械理解。采用扩展有限元法建立了晶体塑性有限元模型，采用存储能量密度断裂准则模拟了多晶组织中的裂纹扩展，并与实验数据进行了比较。开发了一种新的FCG速率解析解，便于快速估算。该模型基于SED断裂准则，但与经典断裂力学相结合，可以以更高的速率进行裂纹尖端SED计算。正在进行的其他工作旨在捕捉辐照对短FCG速率的影响。在存在裂纹的情况下，研究了位错通道的清除。进一步的实验工作旨在了解氢化物对锆合金-4中短FCG的影响。一系列研究的第一项已经开始。最后，将进行研究，将以前的工作联系起来。第一个目标将是模拟前面提到的结合德尔塔-氢化物相的实验。第二个目标是将辐照损伤模型纳入对氢化锆-4辐照损伤的理论评估。

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.