Experimental investigation on low-velocity impact response of spherical core sandwich structure

In the present work, the low-velocity impact characteristics of the spherical core sandwich structures made of glass fibre reinforced plastic (GFRP) are tested at different strike velocities (3, 5, and 7 m/s). Four different types of core orientation, namely, regular, interlock, inverted, and stagger, are designed and fabricated by the hand-layup method. Vinyl ester resin and woven glass fibre fabrics are used as matrices and reinforcements, respectively. The diameter of the spherical core and the pitch distance is chosen as 16 mm and 32 mm, respectively. The impact behaviour of the novel spherical sandwich structures is examined based on the maximum contact force, energy absorption capacity, coefficient of restitution (COR), and damage behaviour. The Regular model shows enhanced energy absorption capacity with a specific absorbed energy of 0.092 J/(kg/m3) at 7 m/s impact velocity. Similarly the Interlock model shows good damage resistance. The typical failure patterns observed in the Interlock model at 3 m/s are matrix cracking (MC) and fibre breakage (FB), whereas, at 5 and 7 m/s impact velocities, the damage core crushing (C) is observed.