微小き裂からき裂が発生するための限界応力

概要

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The value of ΔK_<eff,th> for a medium carbon steel (0.46%C) was measured by a rotating bending fatigue test using specimens which were annealed after introducing fatigue cracks. Since the fatigue cracks become ideal cracks after annealing, ΔK_<eff,,th> can be determined by finding the critical stress under which no crack growth occurs. The values of K_<op>/K_<max> for a stationary fatigue crack in the rotating bending fatigue test(R=-1) were estimated by the Dugdale model as K_<op>/K_<max>=-1.0 over a wide range of stresses. The values of ΔK_<eff,th> obtained in this study were 3.4〜3.6 MPa・m^<1/2> and were approximately independent of crack size in the range from 100 μm to 1 000 μm. The importance of this value for short cracks is emphasized from the view point of fatigue under varying loads which include both high and low stress amplitudes.
一般社団法人日本機械学会の論文
1987-05-25