Effect of ply-thickness on the impact response of interleaved thin-ply non-crimp-fabric laminates: X-ray tomography investigation

Abstract

Composite laminates subjected to out-of-plane loads develop damage modes that compromise the load-carrying capacity, as in the fuselage skin of an aircraft. Therefore, we aimed to improve the damage resistance and tolerance of carbon/epoxy thin non-crimp fabric (NCF) laminates by (a) reducing the ‘conventional’ ply-thickness (i.e. comparing thick- and thin-plies) (b) interleaving co-polyamide (CoPA) non-woven veils at the interlaminar regions of thin-ply systems. We devised an impact, compression after impact (CAI) and quasi-static indentation (QSI) experimental campaign, where computerized X-ray tomography provided detailed 3D insight on how matrix cracking, delamination and fibre failure interacted during impact and QSI. Thin-ply laminates reduce the amount of matrix cracking and delamination at the cost of premature fibre breakage, therefore decreasing the damage tolerance. Interleaving CoPA veils arrests delamination onset and improves the residual strength with respect to the thin-ply baseline.   [1] S.Sihn, R.Y. Kim, K.Kawabe and S.W. Tsai, Compos. Sci. Technol., vol. 67, no. 6, pp. 996–1008 (2007). https://doi.org/10.1016/j.compscitech.2006.06.008[2] V.A.Ramirez, P.J.Hogg and W.W.Sampson, Compos. Sci. Technol., vol. 110, pp. 103–110 (2015). https://doi.org/10.1016/j.compscitech.2015.01.016