延性き裂発生・進展抵抗の材料依存性評価のための数理損傷モデルの提案 : 延性き裂進展シミュレーション手法の構築(力学特性)

概要

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This study develops a damage model for characterizing the ductile crack growth on the bases of observation of micro-void nucleation for recent structural steels. The resistance to ductile crack initiation is controlled by a local strain at the tip of a notch or a fatigue pre-crack of a specimen. On the other hand, ductile crack extension is controlled by a stress triaxiality dependent critical strain for ductile failure obtained by tension tests of circumferentially notched round-bar specimens. In steels used, the main process for ductile failure is nucleation of micro-voids, whose size is in the order of 1 μm, that are generated at the final stage of ductile failure. According to these observations, a damage model is proposed for simulating the ductile crack extension. This model enables the prediction of the crack growth resistance in terms of CTOD for fatigue pre-cracked specimens with two different crack depth ratios a_0/W, where a_0 is the initial crack length and W is the specimen width.
社団法人日本鉄鋼協会の論文
2008-06-01