Study on fast crack propagation and arrest behavior of a long crack in steel

根据断裂力学的概念，用止裂韧性K&lt；ca&gt；来测量材料的止裂性能。近年来的动态断裂力学实验研究表明，相对较短的止裂裂纹与较长的止裂裂纹具有不同的止裂性能。这种差异可能来自这样一个事实，即这些分析本质上是基于Griffith类型的能量准则，而Griffith类型的能量准则只是一个必要条件。因此，应该考虑局部应力准则，这可能是一个充分条件，以阐明裂纹止裂行为。在本研究中，提出了一个结构钢脆性裂纹扩展和止裂的简单模型。对霍尔模型进行了修正，考虑了裂纹尖端区的塑性功，并假定HRR应力场计算裂纹尖端局部应力。基于所提出的模型，分析了模拟常规和宽板试验的脆性裂纹扩展和止裂行为。结果表明，局部应力判据而不是能量判据控制了结构钢裂纹的止裂过程。

Crack arrestability of the material has been measured by a crack arrest toughness K_<ca> based on fracture mechanics concept. Recent experimental studies involving dynamic fracture mechanics analysis show that there is a discrepancy between crack arrest property associated with relatively short arrested crack and that with very long crack. This discrepancy may come from the fact that these analyzes are essentially based on Griffith type energy criterion, which is nothing but a necessary condition. Thus, local stress criterion which might be a sufficient condition should be taken into account in order to clarify the crack arrest behavior.In this study, a simple model for brittle crack propagation and arrest in structural steel is proposed. The hall's model is modified to account for plastic work done in the crack tip region, and HRR stress field is assumed to evaluate crack tip local stress. Based on the model proposed, brittle crack propagation and arrest behaviors simulating both conventional and wide plate experiments are analyzed. The results show that local stress criterion rather than energy criterion controls the crack run-arrest process in structual steel.