평활시험편에 있어서 균혈형상비 변화에 따른 표면균열의 피로수명과 균열관통거동

The Fatigue Life and Penetration Behavior by Variety of Aspect Ration on Smooth Specimen

Fatigue life and penetration behavior were examined analytically by variety of initial front face crack length and initial crack depth. The fatigue crack shape before penetration is almost semielliptical, and the aspect ratio by calculation using the Newman-Raju's formula is smaller than the value obtained by the experiment. It is found that the crack growth behavior on the back surface after penetration is unique and can be divided into three stage a, b and c. By using the K value proposed by the authors, particular crack growth behavior and the change in crack shape can be evaluated quantitatively. It is found that fatigue life and penetration behavior were more dependent on initial front face crack length than initial crack depth.