A New Approach to the Fatigue Life Prediction for Notched Components Under Multiaxial Cyclic Loading

Zhi-qiang TAO, De-guang SHANG

Abstract


A new fatigue life prediction approach for notched components is proposed under multiaxial cycle loading. Firstly, the pseudo equivalent strain-real equivalent stress relationship is determined by utilizing the Neuber’s rule and the material stress-strain relation under proportional loading. Secondly, the pseudo elastic strain histories at the notch need to be solved for the investigated notched components under multiaxial cyclic loading. Thirdly, for the pseudo elastic strain histories, it is proposed that the Shang–Wang multiaxial fatigue damage parameter can be used to substitute the equivalent strain under proportional loading to take account of the additional hardening due to the non-proportionality of external loadings. Meanwhile, the real equivalent stress amplitude at the notch can be solved. Fourthly, based on the real equivalent stress amplitude at the notch integrated with the Neuber’s rule, the real equivalent strain amplitude can be determined. Finally, the real equivalent strain amplitude is utilized to predict the fatigue crack initiation lifetime of notched components. The proposed method is verified by the experimental data of SAE 1045 notched shaft specimens under proportional and non-proportional cyclic loading. The results showed the prediction errors are mostly within a factor of 2.

Keywords


Multiaxial cyclic loading, Notched components, Fatigue life prediction, Non-proportional hardening


DOI
10.12783/dtetr/ameme2017/16189

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