We present a simplified computational framework based on the cohesive finite element method (CFEM) for predicting the macroscale fracture measures such as K_IC and J_IC of ductile metals as functions of microstructural attributes. Currently, no systematic approach exists to explicitly quantify the effects of grain and grain boundary behavior on the fracture measures of polycrystalline materials. Our computational approach involves embedding a microstructure region around the crack tip in a compact tension specimen subjected to mode-I loading and explicitly resolving fracture processes in the microstructure. To track how the interplay between intergranular and transgranular fracture mechanisms affect the fracture processes and consequently K_IC and J_IC, a grain boundary misorientation dependent interfacial separation model is used. The framework allows exploration of the effects of microstructure on the macroscopic fracture measures via the manifestation of different fracture mechanisms. Calculations carried out for Mo capture and delineate the competing effects between (a) intergranular and transgranular fracture and (b) constituent plasticity and fracture on the overall fracture toughness of the material. The use of statistically equivalent microstructure sample sets (SEMSS) allows the statistical distributions of K_IC to be predicted for Mo with different grain sizes. The results indicate that, as the minimum grain boundary interfacial strength decreases and the grain yield strength increases, intergranular fracture becomes more pronounced over transgranular fracture. Consequently, the plastic dissipation primarily associated with transgranular fracture is suppressed, resulting in lower overall fracture toughness. Microstructures with intermediate levels of grain size exhibit the toughest material response via a combination of tortuous crack paths and plastic dissipation. Finally, the results are analytically quantified in a manner that takes into account the effects of grain boundary characteristics, constituent plasticity, and stochasticity via the use of the SEMSS. Although the calculations here are performed on Mo in a simplified setting, the approach can be extended and applied to other material systems.

我们提出了一种基于内聚有限元方法（CFEM）的简化计算框架，用于预测宏观断裂措施，例如韧性金属的K _IC和J _IC作为微观结构属性的函数。目前，还没有系统的方法来明确地量化晶粒和晶界行为对多晶材料断裂措施的影响。我们的计算方法包括在经受I型载荷的紧凑拉伸试样中将裂纹尖端周围的微观结构区域嵌入，并明确解决微观结构中的断裂过程。为了跟踪晶间和穿晶断裂机制之间的相互作用如何影响断裂过程，并因此ķ_IC和J _IC，使用了晶界取向不正确的界面分离模型。该框架允许通过不同断裂机制的表现来探索微观结构对宏观断裂措施的影响。对Mo的捕获进行了计算，并描述了（a）晶间和跨晶断裂与（b）组成塑性和断裂对材料整体断裂韧性之间的竞争作用。使用统计上等效的微结构样品集（SEMSS）可以对K _IC进行统计分布可以预测具有不同晶粒尺寸的钼。结果表明，随着最小晶界界面强度的降低和晶粒屈服强度的增加，晶界断裂比晶界断裂更为明显。因此，抑制了主要与经晶断裂相关的塑性耗散，导致较低的整体断裂韧性。具有中等裂纹尺寸的微结构通过曲折的裂纹路径和塑性耗散的组合表现出最强的材料响应。最后，通过使用SEMSS，以考虑晶界特征，成分可塑性和随机性影响的方式对结果进行分析量化。尽管此处的计算是在Mo的简化设置下进行的，