基于3D-DIC技术的8.8级高强螺栓延性断裂研究

Study on ductile fracture of grade 8.8 high-strength bolt on the basis of 3D-DIC technology

应力三轴度是控制建筑结构钢材延性断裂的一项重要因素。以国产8.8级高强螺栓为试验材料,借助三维数字成像技术(Three-Dimensional Digital Image Correlation,3D-DIC)研究了典型建筑结构钢材在高应力三轴度水平的断裂行为。研究结果表明:对于建筑结构钢,应力三轴度和断裂应变间呈典型的线性相关关系,据此提出了应力三轴度的简化计算方程;Johnson-Cook断裂模型可以有效反映8.8级高强螺栓的应力三轴度—断裂应变关系,并给出了相应的断裂参数。

Stress triaxiality is an important factor that controls the ductile fracture of structural steels.Based on the Three-Dimensional Digital Image Correlation(3D-DIC)technology,the study experimentally investigated the fracture behavior of typical structural materials by using grade 8.8 high strength bolts.The results indicated that,the stress triaxiality and equivalent fracture strain typically follows a linear relationship,thereby a simplified formula to calculate stress triaxiality is proposed,and for grade 8.8 bolts,the relationship between fracture strain and stress triaxiality could be well expressed by the stress state part of Johnson-Cook fracture model,and the fracture parameters are also demonstrated in this study.