PSI - Issue 42

Matěj Mžourek et al. / Procedia Structural Integrity 42 (2022) 457 – 464 Matěj Mžourek / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Conclusions • Three approaches for assessing the combined size & notch effect were analyzed. One of the two volumetric approaches features the h crit parameter to account for observed near-surface crack initiations. • The Weibull-based model of the influence of the size effect shifts the fatigue curves vertically. Better results should be obtained via also modifying the slope of the curves. • The n stress threshold parameter should not be chosen in an arbitrary matter. The value of this parameter affects the direction in which the Weibull-based model shifts fatigue curves. • The optimal value of the n stress threshold parameter found via regression is strongly dependent on the geometry of analyzed specimens. The optimal value of the parameter in this paper is approximately n = 1/ K t,A02 , but a different value is expected for specimens manufactured from the same material but of different geometries. • Application of the h crit parameter increased fatigue strength estimation accuracy when notched specimens were considered. Such improvement was not present when only unnotched specimens were analyzed. Acknowledgements The support from ESIF, EU Operational Programme Research, Development, and Education, from the Center of Advanced Aerospace Technology (CZ.02.1.01/0.0/0.0/16_019/0000826), Faculty of Mechanical Engineering, Czech Technical University in Prague, and from the Grant Agency of the Czech Technical University in Prague (SGS20/158/OHK2/3T/12) is gratefully acknowledged. References Ai Y, Zhu S-P, Liao D, et al (2019) Probabilistic modelling of Notch fatigue and size effect of components using highly stressed volume approach. International Journal of Fatigue 127:110–119. doi: 10.1016/j.ijfatigue.2019.06.002 Blasón S, Muniz-Calvente M, Koller R, et al (2017) Probabilistic assessment of fatigue data from shape homologous but different scale specimens. application to an experimental program. Engineering Fracture Mechanics 185:193–209. doi: 10.1016/j.engfracmech.2017.05.017 Buch A (1984) Notch-size effect in fatigue of steel specimens - verification of some calculation methods. Materialwissenschaft und Werkstofftechnik 15:338–348. doi: 10.1002/mawe.19840151004 Garwood MF, Zurburg HH, Erickson MA. Correlation of Laboratory Tests and Service Performance. Interpretation of Tests and Correlation with Service, Philadelphia: ASM; 1951, 1–77. Mäde L, Schmitz S, Gottschalk H, Beck T (2018) Combined notch and size effect modeling in a local probabilistic approach for LCF. Computational Materials Science 142:377–388. doi: 10.1016/j.commatsci.2017.10.022 Murakami Y, Masuo H, Tanaka Y, Nakatani M (2019) Defect analysis for additively manufactured materials in fatigue from the viewpoint of quality control and statistics of extremes. Procedia Structural Integrity 19:113–122. doi: 10.1016/j.prostr.2019.12.014 Mžourek M, Papuga J, Matušů M, Mára V, Čapek J, Nesládek M. (2023) Investigation of the size effect on 42CrMo4+QT steel in the high-cycle fatigue domain. Submitted to International Journal of Fatigue . Pavlina EJ, Van Tyne CJ. (2008) Correlation of Yield Strength and Tensile Strength with Hardness for Steels. Journal of Materials Engineering and Performance 17:888–93. doi: 10.1007/s11665-008-9225-5. Sandberg D, Olsson M (2016) An investigation of the prediction accuracy for volume based HCF models using scaled geometries and scaled loading. International Journal of Fatigue 82:317–324. doi: 10.1016/j.ijfatigue.2015.04.024 Schmitz S, Seibel T, Beck T, et al (2013) A probabilistic model for LCF. Computational Materials Science 79:584–590. doi: 10.1016/j.commatsci.2013.07.015 Tom aszewski T, Sempruch J, Piątkowski T (2014) Verification of selected models of the size effect based on high -cycle fatigue testing on mini specimens made of en aw-6063 aluminum alloy. Journal of Theoretical and Applied Mechanics 883. doi: 10.15632/jtam-pl.52.4.883