PSI - Issue 21

Kadir Bilisik et al. / Procedia Structural Integrity 21 (2019) 146–153 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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vicinity of the matrix plastic deformation region. At the same time, nanostitching suppressed the layer separation around the stitching region during the crack growth. In the crack tip, carbon nanotubes in the matrix and filament diminished the stress clustering as a form of filament-matrix debonding; filament or nanotubes pull-out; filament to filament or filament-nanotube sliding or stick-slip action and friction.

Fig. 7. (a) SEM image of warp side fractured region; (b) fractured CS-CS-N composite around the crack tip.

In base composite, resin breakages in the matrix-filament boundaries and minor multiple filament bundle breakages were identified as a form of tensile and shear failures. In nanostitched composite, multiple resin fracture and a few tensile filament bundle breakages were obtained. In addition, minor nanostitching fracture was identified due to using the high modulus filament TOWs. It was realized that nanostitching reponded as a ply-separation barrier around the stitching region. Acknowledgements This work was supported by Roketsan Industries Grant No. RS/ERCİYES DSM -76301-14-01N/R. References ASTM Standard D7905‒14, 2014. Standard test method for determination of the mode II interlaminar fracture toughness of unidir ectional fiber reinforced polymer matrix composites. West Conshohocken, PA. Batra, R. C., Sears, A., 2007. Continuum models of multi-walled carbon nanotubes. International Journal of Solids and Structures 44, 7577 – 7596. Beckermann, G. W., Pickering, K. L., 2015. Mode‒I and Mode‒II interlaminar fracture toughness of composite laminates interleaved with electrospun nanofibre veils. Composites Part A: Applied Science and Manufacturing 72, 11 – 21. Bilisik, K., 2010. Dimensional stability of multiaxis 3D woven carbon preform. Journal of the Textile Institute 101, 380 – 388. Bilisik, K., 2011. Three dimensional axial braided preforms: Experimental determination of effects of structure-process parameters on unit cell. Textile Research Journal 81, 2095‒2116. Bilisik, K., Sahbaz, N., 2012. Structure-unit cell base approach on three dimensional representative braided preforms from 4-step braiding: experimental determination of effect of structure-process p arameters on predetermined yarn path. Textile Research Journal 82, 220‒241. Bilisik, K., Yolacan, G., 2012. Experimental determination of bending behavior of multilayered and multistitched E-glass fabric structures. Textile Research Journal 82, 1038‒1049. Bilisik, K., Sahbaz, N., Bilisik, N. E., Bilisik, H. E., 2013. Three dimensional (3D) fully interlaced woven preforms for composites. Textile Research Journal 83, 2060‒2084. Bilisik, K., Yolacan, G., 2014. Experimental characterization of multistitched two dimensional (2D) woven E-glass/polyester composites under low velocity impact load. Journal of Composite Materials 48, 2145‒2162. Bilisik, K., Erdogan, G., Sapanci, E., Gungor, S., 2019 a. Mode-II toughness of nanostitched carbon/epoxy multiwall carbon nanotubes prepreg composites: Experimental investigation by using end notched flexure. Journal of Composite Materials Epub ahead of print 17 June DOI: 10.1177/0021998319857462. Bilisik, K., Karaduman, N. S., Sapanci, E., 2019 b. Flexural characterization of 3D prepreg/stitched carbon/epoxy/multiwall carbon nanotube preforms and composites. Journal of Composite Materials 53, 563-577. Blake, S. P., Berube, K. A., Lopez-Anido, R. A., 2012. Interlaminar fracture toughness of woven E-glass fabric composites. Journal of Composite Materiels 46, 1583 – 1592. Carlsson, L. A., Gillespie, J. W., Trethewey, B. R., 1986. Mode‒II interlaminar fracture of graphite/epoxy and Graphite/PEEK. Journal of Reinforced Plastics and Composites 5, 170‒187. Davis, D. C., Whelan, B. D., 2011.An experimental study of interlaminar shear fracture toughness of a nanotube reinforced composite. Composites Part B: Engineering 42, 105 – 116.