Impact behavior of plywood core laminated with flax-epoxy composite skin

The introduction of sandwich structures made from materials that are environmentally friendly, light, and strong enough to carry the applied loads is one way of reducing the carbon footprint of the transport industry. This work investigates the impact behaviour of a structure composed of a plywood core and flax/epoxy composite skins, as a proposal for a sandwich structure that takes advantage of the high longitudinal strength of raw timber along the transverse direction across the grain. The variation of peak force, indentation, impact bending stiffness and absorbed energy over a wide range of impact energies is studied, comparing the sandwich structure with the plywood alone. The failure modes (matrix in tension, matrix in compression and delamination) that occur in both the plywood and the sandwich structure have also been studied. The sandwich structure shows superior impact resistance, making it a promising alternative to conventional sandwich structures that is both sustainable and lightweight.