過大応力負荷後の疲労き裂進展の加速とストップホール法によるき裂進展挙動の改善 Acceleration of Fatigue Crack Growth after Overloading and Improving Crack Growth Behavior by Drilling Stop-Hole
When an overload was applied during fatigue crack growth test with constant stress amplitude under negative stress ratio, not only the retardation but also the acceleration of the crack growth was occurred, depending on the experimental conditions. In the present study the acceleration behavior of crack growth after overload was investigated and the method of improving the crack growth behavior of that was investigated. Where the cyclic stress level was higher than a critical level and the overload level was also higher than a critical level, the crack growth rate after overloading was kept higher level than the baseline which is crack growth rate of specimen without applying of overload. It is considered from the experimental results that the crack growth acceleration was caused by the tensile residual stress distribution in front of the crack tips. Therefore, it was discussed that removing the overload plastic zone in front of the crack tips would be effective to improve crack growth behavior of the overloaded specimen. Then the effect of drilling stop-holes at crack tips or in the vicinity of crack tips on crack growth was investigated. The crack growth behavior of the overloaded specimen where stop-holes were drilled and pins inserted into them was compared with that of the base which was obtained by using a specimen without stop-holes. In the case where the stop-holes were drilled, the crack growth behavior of the overloaded specimen was not improved. However, the crack growth behavior after applying overload was improved in the case in which pins were inserted into stop-holes.
- 圧力技術 = Pressure engineering : journal of Japan High Pressure Institute
圧力技術 = Pressure engineering : journal of Japan High Pressure Institute 50(1), 24-32, 2012-01-25