PSI - Issue 33

R. Nobile et al. / Procedia Structural Integrity 33 (2021) 685–694 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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presence of high porosity in the core compared to the opposite side (Fig. 10b below). Finally, the damage modalities of the AFS30 specimens that are found in all the specimens are indentation, detachment, and fracture of the core. The mode of damage in this case appears not to change in the absence or presence of impact damage. The only specimen with skin fracture was observed for the AFS-30_P5 specimen in the presence of impact (Fig. 11b right). a b

Fig. 11. (a) AFS-30 specimens after 3-points bending testes in the absence and (b) in the presence of impact damage.

4. Conclusions In this work, the influence of impact damage on the mechanical bending behavior and failure mechanisms of GFRP sandwich skin panels with aluminum foam of a similar type but with different densities was investigated. The skins of the cross-layer laminates in fiberglass and epoxy resin were produced by hand-layup and subsequent vacuum lamination. The NDT controls on the impacted specimens highlighted the delamination zones identified by both IRT and UT techniques and the deformation zones (identified by UT controls). The specimens obtained were subjected to bending tests on three points in the absence and in the presence of impact damage. It has been shown that the presence of impact damage affects the mechanical behavior and damage methods of the specimens with less thick and less dense foam, a phenomenon not observed for the other type of specimens. Acknowledgements The authors would like to thank Prof. Umberto Galietti, Eng. Davide Palumbo and Eng. Rosa de Finis for sharing thermographic equipment. References Ahmed, S., Lee, S., Cho, C., Choi, K. K., 2011. Experimental study on low velocity impact response of CFRP-aluminum foam core sandwich plates, 18th International Conference on Composite Materials. Jeju, Korea, in Proc. of ICCM18. Cho, U., Hong, S. J., Lee, S. K., Cho, C., 2012. Impact fracture behaviour at the material of aluminium foam. Materials Science and Engineering: A 539, 250 – 258. Dattoma, V., Castriota, A., Nobile, R., Panella, F. W., Pirinu, A., Saponaro, A., 2018. Numerical and experimental analysis of aeronautical CFRP components subjected to structural loads. 6th International Conference Integrity-Reliability-Failure, Lisbon, Portugal, in Proc. of IRF2018. Frostig, Y., 1992. Behavior of delaminated sandwich beam with transversely flexible core – high-order theory. Composite Structures 20, 1 – 16. Hashim, A. H., Nordin, Jumahat, A., Ismail, M. H., 2014. Compressive Properties of Glass Fibre Reinforced Polymer (GFRP) Rod with Aluminium Foam Core, Advances in Environmental Biology 8 (8), 2780 – 2785. Hosur, M. V., Chowdhury, F., Jeelani, S., 2007. Low-velocity impact response and ultrasonic NDE of woven carbon/ epoxy nanoclay nanocomposites. Journal of Composite Materials 41 (18), 2195 – 2212. Jones, Robert M., 1999. Mechanics of Composite Materials, Taylor & Francis, Inc., Chapter 2: Macromechanical Behaviour of a lamina. Kara, E., Crupi, V., Epasto, G., Guglielmino, E., Aykul, H., 2014. Flexural behaviour of glass fiber reinforced aluminium honeycomb sandwiches in flatwise and edgewise positions, 16th European Conference on Composite Materials. Seville, Spain, in Proc. of ECCM16.