PSI - Issue 33

Sabrina Vantadori et al. / Procedia Structural Integrity 33 (2021) 773–780 Author name / Structural Integrity Procedia 00 (2019) 000–000

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4. Conclusions In the present research work, the fatigue behaviour of DCI specimens subjected to uniaxial and biaxial cyclic loading under high/medium-cycle fatigue has been theoretically investigated. In particular, the fatigue strength (for both infinite and finite life tests) and the fatigue lifetime (for finite life tests) of the above DCI specimens have been evaluated by means of a stress-based multiaxial fatigue criterion (Vantadori et al. (2020a). On the basis of the obtained results, a quite satisfactory accuracy in the evaluation of fatigue endurance condition has been achieved. Moreover, for finite life tests, the estimated fatigue lives are in good agreement with the experimental ones, and the obtained accuracy level is far greater than that related to the well-known stress invariant based criterion proposed by Crossland in the past. To conclude, it can be said that further investigations are needed in order to theoretically take into account the presence of material intrinsic defects, which strongly affect the fatigue behaviour of DCIs.

4.0 20.0 MEAN SQUARE ERROR , T RMS PRESENT CRITERION CROSSLAND CRITERION 8.0 12.0 16.0

0.0

TENSILE TORSIONAL BIAXIAL

LOADING CONDITION

Fig. 5. Mean square error value for finite life fatigue tests.

Acknowledgements The present research work is supported by Italian Ministry of University and Research (P.R.I.N. National Grant 2017, Project code 2017HFPKZY; University of Parma Research Unit). References Araújo, J.A., Dantas, A.P., Castro, F.C., Mamiya, E.N., Ferreira, J.L.A., 2011. On the characterization of the critical plane with a simple and fast alternative measure of the shear stress amplitude in multiaxial fatigue, International Journal of Fatigue 33, 1092-1100. Bellini, C., Di Cocco, V., Favaro, G., Iacoviello, F., Sorrentino, L., 2019. Ductile cast irons: microstructure influence on the fatigue initiation mechanisms. Fatigue & Fracture of Engineering Materials and Structures 42, 2172– 2182. Benedetti, M., Torresani, E., Fontanari, V., Lusuardi, D., 2017. Fatigue and fracture resistance of heavy-section ferritic ductile cast iron. Metals 7, 88. Borsato, T., Ferro, P., Berto, F., 2018. Novel method for the fatigue strength assessment of heavy sections made by ductile cast iron in presence of solidification defects. Fatigue & Fracture of Engineering Materials and Structures 41, 1746– 1757. Carpinteri, A., Vantadori, S., Łagoda, T., Karolczuk, A., Kurek, M., Ronchei, C., 2018. Fatigue assessment of metallic components under uniaxial and multiaxial variable amplitude loading. Fatigue & Fracture of Engineering Materials and Structures 41, 1306-1317. Cengiz, C., 2012. Out of Phase Multiaxial Fatigue Strength of a Cast Iron (Master thesis). Milan, Politecnico di Milano. Di Cocco, V., Iacoviello, F., 2017. Ductile cast irons: microstructure influence on the damaging micromechanisms in overloaded fatigue cracks. Engineering Failure Analysis 82, 340-349.