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

Zircaloy-4合金的疲劳裂纹扩展速率(FCG)和裂纹路径在微观结构上高度敏感，并且依赖于织构。这项工作的目的是从机理上了解这些微观结构效应。采用扩展有限元方法和储能密度断裂准则的晶体塑性有限元模型，模拟了多晶微结构中的裂纹扩展，并与实验数据进行了比较。提出了一种新的FCG频率的解析解，便于快速估计。该模型基于SED断裂准则，但与经典断裂力学相关联，从而能够以更高的速率进行裂纹尖端SED计算。其他正在进行的工作旨在捕捉短FCG率上的辐射效应。在存在裂纹的情况下，位错通道的清除正在进行研究。另外的实验工作是为了了解氢化物对Zircaloy-4中短FCG的影响。一系列研究中的第一项已经开始。最后，将进行研究，将以前的工作联系起来。第一个目标是模拟前面提到的从加入三角洲-氢化物相的实验。第二个目标是纳入辐射损伤模型，对氢化锆-4的辐射损伤进行理论评估。

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.