溝を有する試験片の疲労き裂伝ぱと応力拡大係数の評価について

概要

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In oeder to predict the fatigue life of machine equipment,the fatigue crack propagation law is usually investigated by using smooth specimens.However,few investigations of the crack propagation have been carried out on the specimens having the cross-section of complicated shape.In this study,the specimen with three grooves which were cut in the loading direction was used to clarify the crack propagation and the crack clsure behavior at the suddenly changed site of the thickness.The crack propagation rate was observed to be once accelerated and then decelerated in the vicinity of the first groove.The variation of crack clsure point was different between the grooved specimen and the smooth specimen.The stress intensity factor was evaluated using the calibration curve between the crack propagation rate and the stress intensity factor of the grooved specimen was higher in front of the first groove and lower behind it,compared to the smooth specimen.The crack propagation law evaluated with K_<max> becomes complicated in the vicinity of the first groove due to the change of thickness.Thus,the crack propagation rate once increases and thendecreases with the maximum value of stress intensity factor K_<max> when the crack crosses the groove.
社団法人日本材料学会の論文
1993-11-15