PSI - Issue 42

Jakub Šedek et al. / Procedia Structural Integrity 42 (2022) 398–403 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Discussion FE results show the linear response of the load-displacement curve up to the point of stiffness change. It is related to buckling. Three half-waves developed in each section followed by four half-waves. The corresponding load is compared in Fig. 4b. The FE results are higher mainly for the pristine panel. Further, some perturbations were observed since the nature of the dynamic solver. The mass scaling applied for explicit solver was probably the reason for the inertia effect when changing the flat skin shape to buckled shape with out-of-plane displacements. Predicted failure loads are very close to the test for both, pristine and cracked panels. The development of the collapse was also captured accordingly. The bonding behaviour between sub-parts revealed as crucial for proper simulation of the failure. 6. Conclusion The analyses of the pristine and cracked panels under compressive load were carried out. The detailed FE model was created to simulate the buckling behaviour and the collapse as observed during the test. Cohesive elements were utilized between the skin, webs and caps in the FE model to capture the real failure mode of the panel. The explicit solver was used in the analysis. The FE model predicts panel collapse of 3% less for pristine and of 9% less for the cracked panel in comparison with the test. The failure mode was simulated in accordance with the test; i.e. the separation of sub-parts occurred during the collapse of both panels. The bonding properties of the interface between skin and stringers were identified as key to strength. Acknowledgements The work was carried out with the support by European Uni on’s Horizon 2020 research and innovation programme under the call H2020-CS2-CFP09-2018-02, the grant agreement No 865123, project TAILTEST - Development of a multipurpose test rig and validation of an innovative rotorcraft vertical tail. References Cytec. (2012) APC-2 PEKK Thermoplastic Polymer Technical Data Sheet. Cytec Engineering Materials. van Ingen JW, Waleson J.E.A, Offringa A, Chapman M. (2019) Double curved thermoplastic orthogrid rear fuselage shell. In: SAMPE Europe conference. Nantes, France; 2019, p. 1–10. von Kármán Th., Sechler E. E. and Donnell L.H. (1932) The strength of Thin Plates in Compression, Transaction A.S.M.E, Vol. 37, pp. 22-40, 1932 Kassapoglou Ch. (2010) Design and Analysis of Composite Structures With Applications to Aerospace Structures, 1th ed., John Wiley and Sons, UK, ISBN: 9780470972717 Hashin Z. and Rotem A. (1973) A Fatigue Failure Criterion for Fiber-Reinforced Composite Materials. Journal of Composite Materials, 7, 448 464. DOI: 10.1177/002199837300700404 Šedek J., Vlach J. and Horňas J . (2022) Ply-by Ply Model Application in Analyses of Composite Structures by Finite Elements, In: Experimental Stress Analysis 2022, Book of Extended Abstracts, Prague, Czech Republic, 6th-7th June 2022, CTU in Prague, pp. 134–135, ISBN 978-80 01-07010-9 Tan, W., & Falzon, B. (2016). Modelling the nonlinear behaviour and fracture process of AS4/PEKK thermoplastic composite under shear loading. Composites Science and Technology, 126, 60-77. https://doi.org/10.1016/j.compscitech.2016.02.008 Yu Ch. and Schafer B., (2007) Effect of Longitudinal Stress Gradients on Elastic Buckling of Thin Plates, Journal of Engineering Mechanics, DOI: 10.1061/(ASCE)0733-9399(2007)133:4(452)