PSI - Issue 38

Sara Eliasson et al. / Procedia Structural Integrity 38 (2022) 631–639 Author name / Structural Integrity Procedia 00 (2021) 000 – 000

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indicating a specimen with less flaws and a more stable fatigue damage development. The size of the strain for AT0_6 is also lower. Utilizing these data for design with a UD CFRP material it is important to consider the variation of the results. Both the knowledge of the stiffness degradation behavior and the fatigue limit could be used as fatigue design guidelines. 6. Conclusions - The fatigue limit of the UD CFRP material indicates being at least 80 % of UTS. - Differences in the strain development over time can be connected to the high spread in the fatigue results and the varying failure modes of the specimens. - A strain design criterion should be set after a fatigue specimen with a lower strain that has a stable development of strain and stiffness degradation over time, since this is the most conservative. Acknowledgements The authors would like to thank the Centre for ECO2 Vehicle Design, funded by the Swedish Innovation Agency Vinnova (Grant Number 2016-05195), and Scania CV AB for financial support. References André, D., 2017. Pydic - a python suite for local digital image correlation. Version 1.0. Limoges, France. ASTM International, 2012. ASTM D3479/D3479M-12 Standard Test Method for Tension-Tension Fatigue of Polymer Matrix Composite Materials. West Conshohocken, PA 19428-2959 United States. ASTM International, 2017. ASTM D3039/D3039M-17 Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials. West Conshohocken, PA 19428-2959 United States. Blaber, J., Adair, B. and Antoniou, A., 2015. Ncorr: Open-Source 2D Digital Image Correlation Matlab Software. Experimental Mechanics, 7, 55(6), pp. 1105-1122. Eliasson, S., Wanner, S., Barsoum, Z. and Wennhage, P., 2019. Development of fatigue testing procedure for unidirectional carbon fiber composites. Procedia Structural Integrity, Volume 19, pp. 81-89. Gamstedt, E. K. and Talreja, R., 1999. Fatigue damage mechanisms in unidirectional carbon-fibre-reinforced plastics. Journal of Materials Science, Volume 34, pp. 2535-2546. LePage, W. S., Shaw, J. A. and Daly, S. H., 2017. Optimum Paint Sequence for Speckle Patterns in Digital Image Correlation. Experimental Techniques, 10, 41(5), pp. 557-563. Reifsnider, K. L., Schulte, K. and Duke, J. C., 1983. Long-Term Fatigue Behavior of Composite Materials, ASTM International. Schulte, K., 1999. Cyclic mechanical loading. In: Reinforced plastics durability. Cambridge: Woodhead Publishing Limited, pp. 151-185. Senthilnathan, K. et al., 2017. Microstructural damage dependent stiffness prediction of unidirectional CFRP composite under cyclic loading. Composites Part A: Applied Science and Manufacturing, 9, Volume 100, pp. 118-127. Sisodia, S., Gamstedt, E. K., Edgren, F. and Varna, J., 2015. Effects of voids on quasi-static and tension fatigue behaviour of carbon-fibre composite laminates. Journal of Composite Materials, 49(17), pp. 2137-2148. Sisodia, S., Kazemahvazi, S., Zenkert, D. and Edgren, F., 2011. Fatigue testing of composites with in-situ full-field strain measurement. 18th International Conference on Composite Materials. Jeju Island, Korea. Van Paepegem, W., 2010. Fatigue damage modelling of composite materials with the phenomenological residual stiffness approach. In: Fatigue life prediction of composites and composite structures. Woodhead Publishing Limited, pp. 102-138. Wenner Berg, L. J., 2020. Fatigue Testing of a Unidirectional Carbon Fiber Reinforced Polymer - Investigation of damage development using Digital Image Correlation, Degree Project in Mechanical Engineering. Stockholm: KTH Royal Institute of Technology. TRITA-SCI-GRU; 2020:354.