鋼材の脆性き裂伝播停止挙動に関する : 考察

概要

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Crack arrestability of the material has been measured by a crack arrest toughness Kca 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 analyses 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 paper, 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 type experiments are analyzed. The results show that local stress criterion rather than energy criterion controls the crack run-arrest process in structual steel.