鋼材の脆性き裂伝播・停止の力学モデル(2) : 温度勾配型試験への適用

概要

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Fracture mechanical model, which is based on local fracture stress criterion and takes account of the effect of crack closure stress by unbroken ligaments formed near the plate surface and of crack-bowing inside the plate, is extended to a crack propagation and arrest simulation in a specimen with temperature gradient. The model reproduced acceleration, deceleration and arrest behavior of a crack. With increasing crack length and increasing temperature at crack-tip, thickness and length of the ligaments increase, thereby increasing the effect of crack closure by the ligament and bringing about crack-arrest. The crack is arrested at a point where dynamic fracture toughness versus crack velocity curve shows a minimum. Nominal arrest toughness calculated from applied stress and arrest crack length showed Arrhenius type temperature dependency. The nominal arrest toughness weakly depends on temperature gradient.