PSI - Issue 28

Wei Song et al. / Procedia Structural Integrity 28 (2020) 200–207 Author name / Structural Integrity Procedia 00 (2020) 000 – 000

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4. Conclusion In the current study, six different fatigue damage parameters, which express by strain or energy values combining with critical plane criteria, notch gradient, stress concentration factor, were evaluated for 10CrNi3MoV steel and its undermatched weldments under multiaxial low cycle fatigue loadings. The following conclusions can be summarized from the current research: (1) A modified SWT energy fatigue damage parameter is proposed for multiaxial low cycle fatigue analysis, in which stress concentration factor and additional material constant are introduced to describe the notch effect associated with the critical plane. (2) The fatigue damage parameters on the basis of effect critical distance and notch gradient can successfully evaluate the variation of characteristic values of notched components subjected to multiaxial low cycle fatigue loading, and this holds true dependently of the geometrical feature. (3) For in-phase proportional and 90 º non-proportional loadings, FS, FS-M and Made models provide conservative prediction results of fatigue life, While, the ZSP and Macha multiaxial fatigue models give slight non conservative prediction results. The proposed fatigue model in terms of energy damage incorporating the energy concentration factor provide more accurate multiaxial low cycle fatigue life predictions for notch specimens, which implies this model is more suitable for notch components. References [1] Liao D., Zhu S., Correiac J., Jesusc A., Calçadac R., Computational framework for multiaxial fatigue life prediction of compressor discs considering notch effects , Eng. Frac. Mechanics. [2] Fatemi A, Socie DF., A critical plane approach to multiaxial fatigue damage including out-of-phase loading. Fatigue Fract Eng Mater Struct. 11 (1988): 149 – 66. [3] Takahiro M., Takamoto I., Evaluation of multiaxial low cycle fatigue life for type 316L stainless steel notched specimen under non-proportional loading. Theor. Appl. Fract. Mech. 84 (2016) 98-105. [4] Nicholas R.G., Ali F., On the consideration of normal and shear stress interaction in multiaxial fatigue damage analysis. Int. J. Fatigue 100 (2017) 322-336. [5] Ellyin, F., Fatigue damage, crack growth and life prediction, Edmonton: Chapman and Hall (1997). [6] Jinsoo P., Drew N., Evaluation of an energy-based approach and a critical plane approach for predicting constant amplitude multiaxial fatigue life. Int. J. Fatigue 22 (2000) 23-39. [7] Daniel K., Phani C., On Deviatoric Interpretation of Neuber’s Rule and the SWT Paramete rs. Theor. Appl. Fract. Mech. 71 (2004) 98-105. [8] Andrea C., Filippo B., Alberto C., Fatigue assessment of notched specimens by means of a critical plane-based criterion and energy concepts. Theor. Appl. Fract. Mech. 84 (2016) 57-63. [9] Macha E, Niesłony A. Critical plane fatigue life models of materials a nd structures under multiaxial stationary random loading: the state-of the-art in opole research centre cesti and directions of future activities. Int. J. Fatigue, 39 (2012), 95-102. [10] Mäde L, Schmitz S, Gottschalk H, Beck T. Combined notch and size effect modeling in a local probabilistic approach for LCF. Computational Materials Science, 142 (2018) 377-388.