基于弥散燃料颗粒开裂的金属基体裂纹特征模型

金属基弥散燃料元件在特殊工况下会发生表面起泡失效。燃料颗粒开裂是金属基体开裂的前提条件，只有当金属基体开裂后元件才会发生表面起泡。燃料颗粒开裂后，裂纹宽度和塑性区长度等裂纹特征决定了金属基体开裂行为。基于弹塑性断裂力学和应力平衡条件，建立了基于弥散燃料颗粒开裂的金属基体裂纹特征模型。计算结果表明：裂纹张开位移随退火温度和燃耗深度的升高而增加；裂纹尖端塑性区长度主要与退火温度相关。裂纹张开位移和塑性区长度的计算结果与实验数据均符合较好，验证了金属基体裂纹特征模型的有效性。

Crack Characteristic Model of Metal Matrix Induced by Dispersion Fuel Particle Cracking

Metal matrix dispersion fuel will be vitiated in the form of surface blistering under special conditions. Fuel particle cracking is the precondition of metal matrix cracking, and surface blistering will occur only when the metal matrix is cracked. After fuel particle cracking, the crack characteristics, such as crack width and plastic zone length, determine the cracking behavior of metal matrix. Based on the elastic-plastic fracture mechanics and stress equilibrium, the crack characteristic model of metal matrix induced by dispersion fuel particle cracking was established. The calculation results show that the crack opening displacement increases with the annealing temperature and the burnup. The length of plastic zone at the crack tip is mainly related to annealing temperature. The calculated results of crack opening displacement and plastic zone length are in good agreement with the experimental data, verifying the validity of the crack characteristic model of metal matrix.