PSI - Issue 53

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Martin Stepanek et al. / Procedia Structural Integrity 53 (2024) 58–64 Author name / Structural Integrity Procedia 00 (2019) 000–000

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4. Conclusions The prediction of the fatigue life compared to the real service life (in this case very accurately simulated in laboratory conditions) usually shows a certain deviation. This is because the fatigue life calculations are not based on any exact physical law, but are based on hypotheses, in this case on the chosen multiaxial criteria. The acceptability of the hypothesis/criterion is usually evaluated by a factor of two, i.e., the hypothesis/criterion is acceptable if the calculated and predicted fatigue life does not differ by more than a factor of two. Such a difference can be taken into account by choosing a reasonable safety factor for fatigue life. The most appropriate experimentally verified hypothesis/criterion can then be used for sizing/assessing specific components (functional samples) made from the given materials. In Fig. 9 is a milling head with the trade name KRAKEN and two of its optimized variants.

Fig. 9. KRAKEN milling head and its optimized variants.

Other components developed with a similar approach were: the turning knife, the folding mechanism of a wheelchair, a protective frame holder of a low-floor tram. The contribution describes only the basic technical conditions of the project and the chosen methodological procedure. The specific values of the experiments and calculations will be presented in a special issue of the journal Fatigue and Fracture of Engineering Materials and Structures. Acknowledgments The project with the designation FW01010462 entitled "Computational and experimental support for 3D printing of metal components made by DMLS technology and exposed to multiaxial fatigue loading" was financially supported by the Technology Agency of the Czech Republic. References Chmelko, V., Margetin, M., 2020. The performance of selected multiaxial criteria under tension/torsion loading conditions. International Journal of Fatigue 135 (2020) 105532. Findley, W.N., 1957. Fatigue of metals under combinations of stresses. Trans ASME 1957; 79:1337–8. Findley, W.N., 1959. A theory for the effect of mean stress on fatigue of metals under combined torsion and axial load or bending. Trans ASME 1959; 81:301–5. Dang Van, K., Griveau, B., Message, O., 1989. On a new multiaxial fatigue limit criterion: theory and application. Biaxial and multiaxial fatigue, EGF 3. London: Mechanical Engineering Publications; pp. 479–96. Dang-Van, K., 1993. Macro-micro approach in high-cycle multiaxial fatigue. In: McDowell DL, Ellis R, editors. Advances in Multiaxial Fatigue, ASTM STP 1191. Philadelphia: American Society for Testing and Materials; pp. 120–30. Carpinteri, A., Macha, E., Brighenty, R., Spagnoli, A., 1999. Expected principal stress directions for multiaxial random loading – Part I: theoretical aspects of weight function method. International Journal of Fatigue; 21:83–8. https://doi.org/10.1016/S0142-1123 (98) 00046-2. Carpinteri, A., Spagnoli, A., Vantadori, S., 2003. A multiaxial fatigue criterion for random loading. Fatigue Eng. Mater. Struct. 26:515–22. https://doi.org/10.1046/j.1460-2695.2003.00620.x.