Modeling of microscopic crack formation to predict crack propagation resistance

由于钢结构脆性断裂具有突发性和不可控制性，因此预防脆性断裂是钢结构完整性的重要考虑因素之一。在这项研究中，我们进行了系统的实验和测量，以了解脆性裂纹扩展的微观机制。然后，我们开发了数值模型来定量评估裂纹的扩展。首先，我们澄清了解理面配方的温度依赖性。此外，我们还开发了一个数值模型来模拟晶粒中的几何解理面。其次，结合力学和金相学的知识，建立了裂纹分支的数值模型。验证结果表明，该模型可以预测裂纹分支起裂概率。

The prevention of brittle fracture is one of the most important considerations for structural integrity of steel structures because of the sudden and uncontrolled nature of such failures. In this study, we conducted systematic experiments and measurements to understand microscopic mechanism of brittle crack propagation. We then developed numerical models to quantitatively evaluate the crack propagation.First, we clarified temperature dependence of formulation of cleavage facets. In addition, we developed a numerical model to simulate geometries cleavage facets in a grain. Second, we developed numerical model of crack branching by unifying the knowledges of mechanics and metallography. Results of validation showed probability of crack branching initiation can be predicted by using the proposed model.