破面生成エネルギーを考慮した高張力鋼の脆性き裂伝ば数値モデル: 脆性き裂伝ぱ数値モデルの構築　第1報

摘要

Brittle fracture propagation issue has been focused from the viewpoint of margin of safety in some steel structures which require high fracture safety. In this study, Importance of absorption of fracture surface energy(G_c) during cleavage crack propagation in poly-crystal material is pointed out. Model experiment at -196 deg.C by Compact Crack Arrest specimen and FEM analyses based on the local stress criterion method were performed using YP32 steel and its material constant considering G_c concept. FEM analyses where the critical stress,δ_f is set to 2150MPa which is the same value as its critical stress for crack initiation and G_c is set to be 500J/m~2 show excellent agreement with experiment in their crack propagation velocity and arrested location.%動的き裂伝ぱに関する研究は,Griffith(1921)のエネルギー論に基づいた破壊力学の創立から30年後頃から行われるようになり,初期にはMott(1948),Yoffe(1951),Broberg(1960),Craggs(1960)らにより,エネルギー平衡条件によるき裂伝ぱ速度加速現象や,脆性き裂が一定速度に飽和する定常状態の理論的考察がなされた.それらの基礎式は,き裂伝ぱが進行する際のエネルギー変化として,以下の式(1)こより示されるものである.