Developing a numerical method to accurately simulate the brittle crack propagation phenomenon is crucial for ensuring the safety of large-scale steel structures. Although recent studies have demonstrated that using the local fracture stress criterion as the fracture condition is effective, the most critical issue is that the methods for evaluating local stress in the vicinity of the dynamically propagating crack front have not been established. To address this, this paper proposes a strategy for analysing a dynamically propagating crack in 3D solids on the basis of the s-version finite element method (s-method). In the proposed strategy, the local mesh is defined in the vicinity of the crack front as an ideal structured mesh aligned with both the crack front direction and crack propagation direction to accurately simulate the local stress field. The dynamically propagating crack front was modelled by a combination of the nodal force release method and local mesh update. The proposed strategy was verified by evaluating the accuracies of the local stress in stationary and dynamically propagating circular crack problems as well as those of the stress intensity factor. The results demonstrate that the proposed strategy provides unprecedented accuracy and efficiency of local stress evaluation in problems of dynamic crack propagation in a 3D solid without requiring any complicated remeshing procedures. Therefore, the proposed strategy has potential as the basis of a numeral framework for analysing dynamic brittle crack propagation problems dominated by the local fracture stress criterion.

开发一种精确模拟脆性裂纹扩展现象的数值方法对于确保大型钢结构的安全至关重要。虽然最近的研究表明，使用局部断裂应力准则作为断裂条件是有效的，但最关键的问题是评估动态扩展裂纹前沿附近局部应力的方法尚未建立。为了解决这个问题，本文提出了一种基于 s 版本有限元方法（s 方法）分析 3D 实体中动态扩展裂纹的策略。在所提出的策略中，将裂纹前沿附近的局部网格定义为与裂纹前沿方向和裂纹扩展方向对齐的理想结构化网格，以准确模拟局部应力场。动态扩展裂纹前沿采用节点力释放方法和局部网格更新相结合的方法进行建模。通过评估静态和动态传播的圆形裂纹问题中局部应力的准确性以及应力强度因子的准确性，验证了所提出的策略。结果表明，所提出的策略在 3D 实体中的动态裂纹扩展问题中提供了前所未有的局部应力评估准确性和效率，而无需任何复杂的重新网格划分程序。因此，所提出的策略具有作为分析由局部断裂应力准则主导的动态脆性裂纹扩展问题的数字框架的潜力。