Dependence of the Threshold Stress of Micro Crack Propagation on a Stress Ratio

Plane bending and cyclic torsion tests, and a combination of them are first carried out with a stress ratio R=0 using annealed cracked specimens made of carbon steel. The threshold stress of micro fatigue crack propagation under a mixed mode can be well determined using the maximum principal stress...

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Bibliographic Details
Published inTransactions of the Japan Society of Mechanical Engineers Series A Vol. 54; no. 497; pp. 8 - 13
Main Authors KITAOKA, Seiichiro, CHEN, Jian-qiao, SEIKA, Masaichiro
Format Journal Article
LanguageEnglish
Japanese
Published The Japan Society of Mechanical Engineers 1988
Subjects
Crack Opening Displacement
Crack Propagation Threshold
Fatigue
Fatigue Limit
Mixed Mode
Stress Ratio
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Summary:Plane bending and cyclic torsion tests, and a combination of them are first carried out with a stress ratio R=0 using annealed cracked specimens made of carbon steel. The threshold stress of micro fatigue crack propagation under a mixed mode can be well determined using the maximum principal stress criterion because of no crack closure in this case. Next, plane bending tests are performed with various stress ratios R. Based on the assumption that crack opening displacement on the threshold level is constant regardless of R, the relation between R and the threshold stress is formulated. The suggested expression is found to be in good agreement with the test results and can be applied to the whole range of the stress ratio.
ISSN:0387-5008
1884-8338
DOI:10.1299/kikaia.54.8