Journal of Ocean Engineering and Technology (한국해양공학회지)

Korean Society of Ocean Engineers (한국해양공학회)
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A Fatigue Life Prediction by Growth Characteristics of a Small Surface Crack

작은 표면균열의 성장특성에 의한 수명예측

  • Suh, Chang-Min (Dept. of Mechanical Engineering, Kyungpook National University) ;
  • Lim, Chang-Soon (Korea Minting and Security Printing Corperation) ;
  • Gang, Yong-Gu (Dept. of Machanical Engineering, Kumoh National Institute of Technology)
  • 서창민 (경북대학교, 기계공학과) ;
  • 임창순 (한국조폐공사대구지사) ;
  • 강용구 (금오공과대학 기계공학과)
  • Published : 1989.12.01

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Abstract

This paper deals with a fatigue life prediction of a surface crack based on the experimentally obtained relationship between surface crack length ratio $a/a_{f}$ and cycle ratio $N/N_{f}$ using micro computer. Firstly $a/a_{f}$-$N/N_{f}$ curves obtained from experimental tests, were assumed as three curves UC(the upper limit curve), LC(the lower limit curve) and MC(the middle curve), and these were utilized to predict the fatigue life. Comparing the calculated values which represent the characteristics of crack growth behaviors from the three assumed curves with the experimental ones, it has been found that in the stable crack growth region, they coincide reasonably well each other. And the differences between the fatigue lives obtained from the assumed curves and the experimental fatigue life did not exceed 20%. Using the characteristics of $a/a_{f}$-$N/N_{f}$ curves, it is possible to predict the da/dN-Kmax curves and the S-$N_{f}$ curves.

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