PSI - Issue 39

J.C. Ehrström et al. / Procedia Structural Integrity 39 (2022) 98–103 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The test is performed under constant amplitude loading at a maximum stress of 135 MPa, R = 0.1. The representation of a lower wing spectrum at a 1g – stress of 90 MPa with a constant amplitude cycling at 135 MPa is conservative. The fatigue test up to 220000 cycles is concluded by a residual strength test at the maximum capacity of the testing machine corresponding to 257 MPa gross stress. This value is well above the 225 MPa required by the common 2.5 factor between 1g – stress and limit stress. The results open the way to the implementation of advanced lower wing covers 25% lighter than the 2024 T351 baseline, when density is considered in addition to stress allowable, with very large inspection intervals. Acknowledgement The authors thank GTM Advanced Structures for manufacturing the bonded panels and Strain Solutions Ltd for the Thermal Surface Analysis. References Beumler, T., 2009. Presentation at the Royal Aerospace Society Hamburg Branch at Hamburg University of Applied Sciences, https://www.fzt.haw hamburg.de/pers/Scholz/dglr/hh/text_2009_10_29_Fiber_Metal_Laminates.pdf, consulted on September 27, 2021. Şen, I., 2015.Lay -up optimization of Fiber Metal Laminates, PhD thesis, Technische Universiteit Delft. Eastin, R.G, Mowery, J. B., 2009, 30 Years of Damage Tolerance – Have we got it right, in ICAF 2009 DOI: 10.1007/978-90-481-2746-7_10 Strain Solutions Ltd https://www.strainsolutions.com/thermoelasticity consulted on September 28, 2021 Torenbeek E., 2013, Advanced Aircraft Design, Wiley. Schijve, J., Vlutters, A.M., Ichsan, Provó Kluit, J.C., 1984, Crack growth in aluminium alloy sheet material under flight-simulation loading, A comparison between TWIST and MINITWIST, FALSTAFF AND SHORT FALSTAFF, Effect of truncating high loads, Delft University of Technology, Department of Aerospace Engineering, Report LR-441. Mendonça W.R.P., da Silva D.F.N.R., 2020, Analysis, Prediction and Correlation of Fiber Metal Laminate Crack Growth in Semi-Wing Full-Scale Test. In: Niepokolczycki A., Komorowski J. (eds) ICAF 2019 – Structural Integrity in the Age of Additive Manufacturing. ICAF 2019. Lecture Notes in Mechanical Engineering. Springer, Cham. https://doi.org/10.1007/978-3-030-21503-3_55 Beumler, T., 2004, Flying GLARE® A contribution to aircraft certification issues on strength properties in non-damaged and fatigue damaged GLARE® structures, PhD Thesis, Delft University of Technology. Hunt, E., Williams, A., Jones, M., 1999, in: Structural Integrity for the Next Millennium, Proceedings of the 20th ICAF Symposium (Internatioanl Committee on Aeronatical Fatigue), Bellevue, Washington, United States. Duprat, D., 2019, Practical Fatigue and Damage Tolerance for Aircraft. First edition (e-book in Kindle format). Fabre, F., Bayona-Carrillo, N., Laye, J., Schuster, U., 2017, FML for Lower Wing Skins, Presentation at the FML Outlook Workshop, Delft Faculty of Aerospace Engineering, 2 – 3 November 2017.