Gladskyi M., Tymoshenko O., Koval V.
National Technical University of Ukraine «Kyiv Polytechnic Institute», Kyiv, Ukraine (
Гладский М.Н., к.т.н., Тимошенко А.В., к.т.н., Коваль В.В.
НТУУ «Киевский политехнический институт», г. Киев ,Украина
ВЛИЯНИЕ КОНЦЕНТРАЦИИ НАПРЯЖЕНИЙ НА ЦИКЛИЧЕСКОЕ ДЕФОРМИРОВАНИЕ СТАЛИ 20 ПРИ РАСТЯЖЕНИИ И КРУЧЕНИИ
Abstract. Notch effects on uniaxial and torsion fatigue behavior of low-carbon steel 20 are investigated in this study. Constant amplitude axial and torsion both load and strain-controlled tests were conducted on smooth and notched tubular specimens. Maximum principal stress theory was chosen as driving parameter for experimental program. Torsion loading resulted in significantly shorter lives and fatigue data could not be correlated by the maximum principal stress theory for smooth specimens. However, considering fatigue notch factor for notched tubes the maximum principal stress theory gives acceptable results. The Finite Element Analysis was used to estimate local stress-strain response at the notch root due to stress concentration. Fatigue strength of notched specimens was predicted based on fatigue strength of the smooth specimens and the fatigue notch factor. As compared to the notched specimens fatigue data the predicted lives are slightly conservative for axial loading and overly conservative for torsion loading.The Fatemi- Socie (FS) critical plane parameter was found to correlate all constant amplitude data of both specimen geometries well since this shear-based critical plane damage parameter represents the actual shear damage crack initiation mechanism experimentally observed for both smooth and notched specimens and under both axial and torsion loadings.
Keywords: Notch deformation, Notch strain, Notch stress, Life Prediction, Low carbon steel
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