PSI - Issue 43

Tereza Juhászová et al. / Procedia Structural Integrity 43 (2023) 172–177 Tereza Juhaszova/ Structural Integrity Procedia 00 (2022) 000 – 000

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The linear part of the data presented in Fig. 4 (b), was fitted using a power function. In Fig. 5, experimental data with fitted functions is plotted. From this fitting, Paris’ law material constants C and m were evaluated. A comparison for all the studied cases is given in Table 2. The constant m does not show a significant variance, but its value grows with the stress ratio R used in the experiment. In contrast, the constant C decreases in relation to the growth of the stress ratio. Table 2. Comparison of the evaluated Paris’s law material constant for the IPE 80 profile and various stress ratios R . Load ratio R [-] m [-] C [mm/no of cycles MPam 1/2 ] 0.1 2.231 1.038 × 10 -8 0.3 2.426 1.330 × 10 -9 0.5 2.524 2.635 × 10 -10 The values of the interval of m for metallic materials are usually from 2 up to 8. In a recent study by Seitl et al. (2022) the influence of a thickness to Paris’ law constants for the same grade of stainless steel was investigated. In comparison, the values in this study for m were in the range between 4.9 and 5.4, and for C it varied between 0.9 4. 9×10 -11 . Conclusion In this contribution, we analyzed the influence of the stress ratio R on the FCGR in an IPE 80 beam made of AISI 304 stainless steel. In total, three specimens were tested under three-point bending with various stress ratios R (0.1, 0.3 and 0.5). To evaluate the experimentally obtained data, a numerical model in the ANSYS Mechanical APDL software was created. The linear part of the experimental data (SIF vs. FCGR) was evaluated using Paris ’ equation. The obtained results of the material parameter m show higher values of the crack growth rate with a higher stress ratio applied. The dispersion of the values does not show a significant trend. These results could be interpreted as a faster growth of a fatigue crack with a greater stress ratio. On the other hand, the values of Paris ’ law constant C show inverse proportionality to the size of the load ratio. The results of this study could also be used in a probabilistic analysis of fatigue damage assessment, see e.g. Krejsa et al. (2016). Acknowledgements The research was supported by the project No. 20-00761S of the Czech Science Foundation, and by the project n.o. FAST-J-22-7959 of the Brno University of Technology internal grant agency. References ANSYS, INC. 2021. Ansys® Academic Mechanical APDL, Release 21.2. Arrayago, I., E. Gardner, R.L., 2015. Description of stress — strain curves for stainless steel alloys. Materials & Design 87, 540 – 552. Baddoo, N.R., 2008. Stainless steel in construction: A review of research, applications, challenges and opportunities. Journal of Constructional Steel Research. 64(11), 1199 – 1206. Braet, L., Juhászová, T., Jindra, D., Marka, P., Seitl, S., 2021. Finding the optimal stress state of a stainless -steel IPE profile for fatigue experiments. Procedia Structural Integrity 33, 1065 – 1072. Eurocode 3: Design of steel structures – Part 1-1: General rules and rules for buildings 2005. Gardner, L., 2005. The use of stainless steel in structures. Progress in Structural Engineering and Materials 7(2), 45 – 55. Gedge, G., 2008. Structural uses of stainless steel - buildings and civil engineering. Journal of Constructional Steel Research 64(11), 1194 – 1198. Irwin, G.R. 1957. Analysis of Stresses and Strains Near the End of a Crack Traversing a Plate. Journal of Applied Mechanics 24(3), 361 – 364. Westergaard, H.M. 1939. Bearing Pressures and Cracks: Bearing Pressures Through a Slightly Waved Surface or Through a Nearly Flat Part of a Cylinder, and Related Problems of Cracks. Journal of Applied Mechanics. 6(2), 49 – 53. Jindra, D., Kala, Z., Kala, J., Seitl, S, 2021. Experimental and Numerical simulation of a Three Point Bending Test of a Stainless Steel Beam. Transportation Research Procedia 55, 1114 – 1121. Krejsa, M., Koubova, L., Flodr, J., Protivinsky, J. and Nguyen, Q. T., 2016. Probabilistic prediction of fatigue damage based on linear fracture mechanics, Frattura ed Integrità Strutturale, 11(39), 143– 159. Murakami, Y. Stress Intensity Factors Handbook. Volume 5. Oxford: Pergamon Press, 2001. Paris, P.C., Erdogan F., 1963. A critical analysis of crack propagation laws. Journal of Fluids Engineering, Transactions 85(4), 528 – 533. Seitl, S., Miarka, P., Kala, Z., Klusák, J., 2017. Effect of rivet holes on calibration curves for edge cracks under various loading types in steel bridge structure. Procedia Structural Integrity 5, 697 – 704 Seitl, S., Pokorný, P., Klusák, J., Duda, S., Lesiuk, G., 2022. Effect of Specimen Thickness on Fatigue Crack Growth Resistan ce in Paris Region in AISI 304 Steel. Fatigue and Fracture of Materials and Structures. Structural Integrity, 24 Tada, H., Paris, P. C., Irwin, G. R., 2000. The stress analysis of cracks handbook. 3rd ed. New York: ASME Press. Tylek, I., Kuchta, K., 2014. Mechanical properties of structural stainless steels. Technical Transactions Civil Engineering 12, 59 – 80.