PSI - Issue 6

Laurence A. Coles et al. / Procedia Structural Integrity 6 (2017) 5–10 Coles et al. / Structural Integrity Procedia 00 (2017) 000–000

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5. Conclusions

When observing the centre point displacement of each specimen, changes in the oscillation period can be seen after the appearance of delamination damage (triple peaks) caused by a reduction of specimen’s stiffness. The global deformation and transitions in curvature of each specimen appeared to be very similar for all the studied air-blast cases, while the out-of-plane displacement increased with the growing pressure as excepted. This behaviour follows the typical deformation typical for this type of specimen fixture and the size of loading area. In contrast to ballistic impact, the distributed character of loading leads to almost instant global flexural bending therefore avoiding any obvious significant localised indentation and associated damage. For the major and failure damage cases, greater deformation of the rear surface was more clearly observed at the free edges, resulting from the initiation of the tensile failure and delamination of the first few plies along the central band of damage. From the X-ray computed tomography results, the cloud of damage was found to grow from the rear surface of the specimens through its thickness towards the front surface as the air-blast magnitude increased. For the minor case, no significant damage was observed, but at the major and failure damage cases the specimens experienced significant damage in the form of tensile failure and widespread delamination propagating from the central line of specimen’s symmetry. Given the similar global flexural bending behavior of all the specimen across all damage cases, the initiation points of damage were consistent to the centre and free edges of the specimens. Acknowledgements The authors would like to acknowledge the experimental support of the Department of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, RI, USA. References Kumar, P., Stargel, D.S., Shukla, A., 2013. Effect of plate curvature on blast response of carbon composite panels. Composite Structures, 99, pp.19–30. Langdon, G.S. Cantwell, W.J., Guan, Z.W., Nurick, G.N., 2014. The response of polymeric composite structures to air-blast loading: a state-of the-art. International Materials Reviews, 59(3), pp.159–177. Langdon, G.S., Lee, W.C., Louca, L.A., 2015. The influence of material type on the response of plates to air-blast loading. International Journal of Impact Engineering, 78, pp.150–160. LeBlanc, J., Shukla, A., Rousseau, C., Bogdanovich, A., 2007. Shock loading of three-dimensional woven composite materials. Composite Structures, 79(3), pp.344–355. Silberschmidt, V.V. (ed.), 2016. Dynamic Deformation, Damage and Fracture in Composite Materials and Structures. Elsevier, Amsterdam e.a., 616 pp. Tekalur, S.A., Shivakumar, K., Shukla, A., 2008. Mechanical behavior and damage evolution in E-glass vinyl ester and carbon composites subjected to static and blast loads. Composites Part B: Engineering, 39(1), pp.57–65.