Size scale effects on post-impact residual strength of hybrid glass/carbon/epoxy Nano-composites

Understanding the material response to macroscopic scaling along the thickness direction in fiber-reinforced composite materials is important to reduce the effects of scaling-up during design. This paper presents the effect of size-scale of composites obtained through two methods of scaling: a) ply -level (0(gn)/90(cn))(s) and b) sub-laminate level (0(gn)/90(cn))(ns) where, (n= 2,3,4), on the residual strength and post-impact response. The strength parameters were determined with and without nano-clay addition (Nanomer 1.30E, clay surface modified with 25-30 wt% octa-decylamine). The hybrid glass/carbon/epoxy composite and nano-composite (1.5% nano-clay of weight of epoxy) specimens were prepared using compression molding technique. The ultimate tensile strength of thickness scaled composite and nano-composite specimen was examined. Impact tests were done at two velocities, viz., 4.49 m/s and 3.78 m/s for both thickness scaled composite specimens with and without nano-composite addition. It was observed that ply -level scaled laminates absorbs more impact energy compared to sub-laminate level scaled specimens. The residual tensile strength was found out by conducting tensile test on the impacted specimens. The reduction in residual strength is more in nano-composite specimens compared to plain-composite material. The damage developed in the ply -level scaled specimen is more compared to sub-laminate level scaled specimens. (C) 2014 Elsevier Ltd.