PSI - Issue 68

Gül Demirer et al. / Procedia Structural Integrity 68 (2025) 190–196 G. Demirer and A. Kayran / Procedia Structural Integrity 00 (2024) 000–000

196

7

Effects of gaps and overlaps

40

30

20

Load [kN]

Quasi-isotropic VS panel- ignoring defects GAP-Defect Layer, 640 elm. OVERLAP-Defect Layer, 640 elm.

10

0

0

0.5

1

1.5

Displacement [mm]

Fig. 6. Load-displacement curves indicating the e ff ects of gaps and overlaps

4. Conclusion

This study presents a numerical buckling analysis of a VS laminate with embedded gaps and overlaps. To incor porate these manufacturing-induced defects into the FE model, two distinct numerical approaches, the defect layer method and the pixelation method, are employed. This comparative study aims to highlight the strengths and limita tions of each method in predicting the influence of gaps and overlaps on buckling load and normalized sti ff ness. The defect layer method demonstrated better convergence with fewer elements, enhancing computational e ffi ciency. In contrast, the pixelation method showed high mesh dependency, requiring a greater mesh density to e ff ectively capture the e ff ects of gaps. The analysis further reveals that gaps diminish both the buckling load and in-plane sti ff ness, while overlaps enhance overall mechanical performance, particularly a ff ecting the buckling load more than the in-plane sti ff ness. Conversely, gaps have a more pronounced impact on reducing in-plane sti ff ness. Blom-Schieber, A., Setoodeh, S., Hol, J., Gurdal, Z., 2008. Design of variable-sti ff ness conical shells for maximum fundamental eigenfrequency. Computers & Structures 86, 870–878. Fayazbakhsh, K., 2013. The Impact of Gaps and Overlaps on Variable Sti ff ness Composites Manufactured by Automated Fiber Placement. Ph.D. thesis. McGill University. Gurdal, Z., Tatting, B., Wu, K., 2005. Tow-placement technology and fabrication issues for laminated composite structures, in: 46th AIAA / ASME / ASCE / AHS / ASC Structures, Structural Dynamics and Materials Conference, AIAA 2005-2017, pp. 1–17. Haddadpour, H., Zamani, Z., 2012. Curvilinear fiber optimization tools for aeroelastic design of composite wings. Journal of Fluids and Structures 33, 180–190. Li, X., Hallett, S., Wisnom, M., 2015. Modelling the e ff ect of gaps and overlaps in Automated Fibre Placement (AFP) manufactured laminates. Science and Engineering of Composite Materials 22, 115–129. Liguori, F.S., Zucco, G., Madeo, A., Magisano, D., Leonetti, L., Garcea, G., Weaver, P.M., 2019. Postbuckling optimisation of a variable angle tow composite wingbox using a multi-modal koiter approach. Thin-Walled Structures 138, 183–198. Lopes, C., Camanho, P., Gu¨rdal, Z., Tatting, B., 2007. Progressive failure analysis of tow-placed, variable-sti ff ness composite panels. International Journal of Solids and Structures 44, 8493–8516. Lopes, C., Gu¨rdal, Z., Camanho, P., 2008. Variable-sti ff ness composite panels: Buckling and first-ply failure improvements over straight-fibre laminates. Computers & Structures 86, 897–907. Marouene, A., Boukhili, R., Chen, J., Yousefpour, A., 2016. E ff ects of gaps and overlaps on the buckling behavior of an optimally designed variable-sti ff ness composite laminates – A numerical and experimental study. Composite Structures 140, 556–566. Nguyen, M.H., Vijayachandran, A.A., Davidson, P., Call, D., Lee, D., Waas, A.M., 2019. E ff ect of automated fiber placement (AFP) manufacturing signature on mechanical performance of composite structures. Composite Structures 228, 111335. Vijayachandran, A.A., Davidson, P., Waas, A.M., 2020. Optimal fiber paths for robotically manufactured composite structural panels. International Journal of Non-Linear Mechanics 126, 103567. Vijayachandran, A.A., Waas, A.M., 2022. Steered fiber paths for improved in-plane compressive response of aerostructural panels: Experimental studies and numerical modeling. Composite Structures 289, 115426. References