疲労き裂伝ぱ寿命がばらつかなくなるき裂長さの定量的予測

抄録

The fatigue crack growth behavior is not reproducible when a crack initiates and grows in a smooth material at a constant stress amplitude. However, a reproducible crack length L₀ has been reported in which the variation in fatigue crack growth rate converges by observation of the crack growth behavior on the specimen surface. However, L₀ volume has not been predicted quantitatively and the physical meaning of L₀ is unknown, so it cannot be used in the design. Therefore, the authors analyzed the L₀ quantitatively by analyzing the growth behavior of the three-dimensional crack front shape which grows inside the material. The aim is to develop a quantitative prediction method for L₀ by analyzing the growth behavior by changing the crack front shape quantitatively. As a result, for the fatigue crack with the ideal crack shape, the possibility of the fatigue crack growth mechanism proposed by the authors was shown. For the complicated shape of the fatigue crack front shape, which depends on the hardness of the microstructures that randomly arranged in front of the fatigue crack, the difference of the stress intensity factor was explained by mechanics. It was shown that the possibility that L₀ physically exists in the fatigue crack with the ideal crack front shape analyzed in this study.