鋳鍛造欠陥の疲労強度評価(その3) : 微小集合欠陥

概要

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As material flaws have great influence on fatigue strength of cast or forged components, it is important to establish evaluation method of fatigue strength for a material with flaws. In the previous studies, fracture mechanics approach using "intrinsic crack model" was made to estimate fatigue strength of material with a round-shaped flaw and with a small flaw. In this paper, evaluation method of fatigue strength was discussed for a material with clustered small flaws, and following results were obtained. (1) Evaluation method of the fatigue strength for a material with clustered small flaws is proposed. This method is based on the fracture mechanics approach using "intrinsic crack model" and equivalent correction factor of nearness of flaws. (2) Estimated fatigue limit by the proposed method agreed with fatigue test results on nodular graphite cast iron (JIS FCD 600) which have many micro-shrinkage cavities. (3) Equivalent correction factor of nearness of the clustered small flaws can be obtained by brittle fracture test on a material which has similar clustered small flaws at an extremely low temperature.
社団法人日本船舶海洋工学会の論文