J積分による疲労き裂伝ぱ速度の評価

概要

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The fatigue crack propagation rate (da/dN) up to I mm/cycle has been obtained for three-points bent specimens of HT 80 steel subjected to gross cyclic plastic deformation. The effect of incremental plasticity on da/dN was examined in terms of maximum J value (J_m), Iike in the case of the effect of maximum stress intensity (K_<max>) in linear fracture mechanics. ΔJ values were determined from the load versus deflection hysteresis loops and J_m values were estimated based on the three parameters method proposed by Garwood et al using the envelope of load versus deflection hysteresis loops. The fatigue crack propagation rate during incremental plastic deflection cannot be predicted by the ΔJ criterion alone, but it can be done by the combination of ΔJ and J_m criteria, giving an agreement with the extrapolation of linear elastic fatigue crack propagation rate data. These experimental results suggest that J_m is a very important parameter for gross plastic crack problems.
社団法人日本材料学会の論文
1978-08-15