弾塑性破壊力学パラメータに基づく繰返し過大荷重による配管材のき裂進展評価法の提案

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概要

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• The magnitude of Niigata-ken Chuetsu-Oki earthquake in 2007 was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the crack growth behaviors due to the cyclic overload like large earthquake. Fatigue crack growth is usually evaluated by Pariss law using the range of stress intensity factor (ΔK). However, ΔK is inappropriate in a loading condition beyond small scale yielding. In this study, the crack growth behaviors for piping materials were investigated based on an elastic-plastic fracture mechanics parameter, J-integral. It was indicated that the crack growth due to the cyclic overload beyond small scale yielding could be the sum of fatigue and ductile crack growth. The retardation effect of excessive loading on the crack growth was observed after the loading. The modified Wheeler model using J-integral has been proposed for the prediction of retardation effect. Finally, an evaluation method for crack growth behaviors due to the cyclic overload is suggested.

著者

• 鬼沢 邦雄

  （独）日本原子力研究開発機構

• 李 銀生

  （独）原子力安全基盤機構

• 山口 義仁

  （独）日本原子力研究開発機構

• 勝山 仁哉

  （独）日本原子力研究開発機構

• 杉野 英治

  （独）原子力安全基盤機構

関連論文

• 弾塑性破壊力学パラメータに基づく繰返し過大荷重による配管材のき裂進展評価法の提案
• 過大な圧縮荷重がき裂進展挙動に及ぼす影響
• 地震荷重下における配管のき裂進展評価手法の提案

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