PSI - Issue 13

A.A. Lukyanchuk et al. / Procedia Structural Integrity 13 (2018) 1285–1290 A.A. Lukyanchuk and others / Structural Integrity Procedia 00 (2018) 000 – 000

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Figure 8 - The S-N curve for fatigue tensile tests of open-hole specimens of CFRP

5. Conclusions

The studies provided a method for experimental determining the fatigue life under tensile tests open-hole CFRP specimens. The method is based on the usage of a sensor, which fixes an increase in the thickness of the specimen in the zone of the hole (delamination). On the basis of the analysis of the obtained experimental data in the process of debugging the method, a failure criterion is proposed: an increase in the thickness of the specimen over 0.05 mm at the zone of concentrator. It is shown that the proposed failure criterion under cyclic loading allows to fix the appearance and propagation of delaminations in the zone of hole. The criterion demonstrates an acceptable repeatability of the physical picture of the initiation of macro destruction, while the fatigue scatter parameter S lgN did not exceed 0.31. Such a fatigue scatter parameter is acceptable for estimating the fatigue life and does not lead to an unreasonable increase in safety factors of fatigue, and hence the duration of certification tests for the aircraft. Acknowledgements The research was financed by Ministry of Education and Science of the Russian Federation, under agreement No.RFMEFI62518X0044 (FENIKS). The authors wish to greatly acknowledge the project partner of FENIKS, Irkut [1] Hahn, H.T., et. al. The Effect of Preloading on Fatigue Damage in Composite Structures: Part I. US Department of Transportation. Federal Aviation Administration. DOT/FAA/AR-95/79. 1996. 48 p. [2] Hahn, H.T., Cho J.B., Lim S.G. The Effect of Loading Parameters on Fatigue of Composite Laminates: Part II. US Department of Transportation. Federal Aviation Administration, DOT/FAA/AR-96/76. 1997. 92 p. [3] Hahn, H.T., Mitrovic M., Turkgenc O. The Effect of Loading Parameters on Fatigue of Composite Laminates: Part III. US Department of Transportation, Federal Aviation Administration. DOT/FAA/AR-99/22. 1999. 69 p. [4] Evaluation of damage tolerance and fatigue structural integration. AR CTs «Prochnost' - Strength» AR MAC, 2015, AC-AR25.571- 1А (Russian). [5] Vassilopoulos, A.P., Keller T., Fatigue of Fiber-reinforced Composites. Springer-Verlag London Limited, 2011, p. 69, 102-104 [6] Wilson, T. Modeling Of In- plane and Interlaminar Fatigue Behavior Of Glass and Carbon Fiber Composite Materials. ‒ Montana State University, Bozeman, Montana, 2007. ‒ 202 p. [7] Konovalov V and Pankov A. Verification of CFRP Components Fatigue Evaluation Procedure under Irregular Cycling Loading. Proc Conference ICAS, Korea, 2016. Corporation. References