PSI - Issue 2_B

Manuela Sander et al. / Procedia Structural Integrity 2 (2016) 034–041 M. Sander et al./ Structural Integrity Procedia 00 (2016) 000–000

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A comparison of the residual lifetimes starting from the smallest inclusion size of 30 µm, from which in experiments a crack initiates, is shown in Fig. 10. It becomes obvious that the approach of Shiozawa et al. overestimates the lifetime, but the slope of the experimental S-N curve matches very well, because the parameters have been calculated from the S-N curve. However, the calculations using the regression line of the Felix experiments with the same crack model also overestimate the lifetime, but match the experimental results better. The overestimation using the regression of the Felix experiments can be explained with interaction effects, which are indicated by the arrest marks on the fracture surface, as well as with the crack growth model, which will be investigated both in future. 4. Conclusions Machines, components and structures are often exposed a very high number of cycles with variable amplitude loadings and different mean stresses. Therefore, experimental investigations for different R -ratios and variable amplitude loadings in terms of the standardized load spectra Felix and WISPER for the high-strength steel 34CrNiMo6 are presented. Due to VHCF testing it could be shown that the mean stress effect is influenced. Moreover, due to variable amplitude loading the S-N curves are shifted to higher lifetimes and arrest marks are produced on the fracture surface surrounding the non-metallic inclusion in the fish-eye. These arrest marks have been used for the calculation of a crack growth curve, with which the lifetimes of the constant amplitude loadings could be reproduced. Acknowledgements The authors thank the German Research Foundation (DFG SA 960/2-2) for the financial support. References Fitzka, M., Mayer, H., 2015. Variable amplitude testing of 2024-T351 aluminum alloy using ultrasonic and servo-hydraulic fatigue testing equipment. Procedia Engineering 101, 169-176 Forschungskuratorium Maschinenbau, 2013. Analytical Strength Assessment of components: FKM Guideline. VDMA Verlag Hück, M., 1983. Ein verbessertes Verfahren für die Auswertung von Treppenstufenversuchen. Zeitschrift für Werkstofftechnik 14, 406-417 Kovacs, S., Beck, T., Singheiser, L., 2013. Influence of mean stresses on fatigue life and damage of a turbine blade steel in the VHCF-regime. International Journal of Fatigue 49, 90-99 Mayer, H., 2006. Ultrasonic torsion and tension–compression fatigue testing: Measuring principles and investigations on 2024-T351 aluminium alloy. International Journal of Fatigue 28, 1446-1455 Mayer, H., Haydn, W., Schuller, R., Issler, S., Bacher-Höchst, M., 2009. Very high cycle fatigue properties of bainitic high carbon-chromium steel under variable amplitude loading. In: International Journal of Fatigue 31, 1300-1308 Mayer, H., Stochjanovic, S., Ede, C., Zettl, B., 2007. Beitrag niedriger Lastamplituden zur Ermüdungsschädigung von 0,15% C Stahl. Mat.-wiss. u. Werkstofftechnik 38, 581-590 Meischel, M., Stanzl-Tschegg, S.E., Arcani, A., Iyyer, N., Apetre, N., Phan, N., 2015. Constant and variable-amplitude loading of aluminum alloy 7075 in the VHCF regime. Procedia Engineering 1011, 501-508 Müller, T., 2016. Einfluss variable Amplitudenbelastungen auf die Rissinitiierung und das Risswachstum im Bereich sehr hoher Lastwechselzahlen. PhD-Thesis, University of Rostock Müller, T., Sander, M., 2013. On the use of ultrasonic fatigue testing technique – Variable amplitude loadings and crack growth monitoring. Ultrasonics 53, 1417-1424 Müller, T., Sander, M., 2013. Experimental and analytical study of the effect of variable amplitude loadings in VHCF regime. ICF 13, Bejing Murakami, Y., 2002. Metal Fatigue: Effects of small defects and non-metallic inclusions. Elsevier, London NASGRO – Fracture Mechanics and Fatigue Crack Growth Analysis Software, Reference manual, Version 6.0, 2009 Newman, J.C. Jr., 1999. Application of small-crack theory to aircraft materials. In: Ravichandran, K. S.; Ritchie, R. O.; Murakami, Y. (eds.): Small Fatigue Cracks: Mechanics, Mechanisms and Applications, Elsevier Science Ltd., Amsterdam, 431-442 Ogawa, T., Stanzl-Tschegg, S., Schönbauer, B., 2014. A fracture mechanics approach to interior fatigue crack growth in the very high cycle regime. Engineering Fracture Mechancis 115, 241-254 Sander, M., Müller, T., Lebahn, J., 2014. Influence of mean stress and variable amplitude loading on the fatigue behaviour of a high-strength steel in VHCF regime. International Journal of Fatigue 62, 10-20 Shiozawa, K., Murai, M., Shimatani, Y., Yoshimoto, T., 2010. Transition of fatigue failure mode of Ni-Cr-Mo low alloy steel in very high cycle fatigue. International Journal of Fatigue 32, 531-550 Stanzl-Tschegg, S., 2014. Very high cycle fatigue measuring techniques. International Journal of Fatigue 60, 2-17