Low-Velocity Impact Response of Sandwich Composites with FRP Facesheets and Nanoclay-Wood Flour Modified Polyurethane Foam

Abstract

Sandwich composite structures are widely used in aerospace, marine, automotive, and other commercial applications due to their high strength to weight ratios, high bending stiffness, high energy absorptions capabilities, and light weight. Traditionally polymer foams serve as the core material for sandwich composites, mainly because of their low density and energy absorption mechanisms due to their cellular structure In an effort to use more environmentally friendly materials, as well as a transition towards the fabrication of more "greener" composites; the fillers used for modifying polyurethane (PU) foam are all derived from natural sources. Three organically-modified nanoclays (Cloisite® 10A, Cloisite® 30B, and Nanomer® I.28E) and maple wood flour were used as fillers. Sandwich panel were fabricated with carbon/epoxy face sheets using vacuum assisted resin infusion molding. Low-velocity impact test was carried out using a drop-weight test system. Three samples of five different sandwich constructions, consisting of neat face sheets and neat and modified foam cores, were tested at energy levels of 10, 20, and 30 joules (J). Transient response data was collected for each sample, which included time, load, energy, velocity, and deflection. Results of the studies showed enhancements in peak load values for nanophased cores in comparison to neat cores.