Post-impact static and cyclic flexural characterisation of hemp fibre reinforced laminates

The suitability for use of plant fibre composites after an impact event is still an open issue in literature. In this work, hemp fibre reinforced laminates have been subjected to cyclic flexural tests following falling weight impact at 12, 16 and 20 J. At these energies, still quite far from penetration, which was at about 40 J, damage starts to be increasingly apparent on both laminate surfaces. Post-impact flexural tests have been monitored using acoustic emission. Laminates with a sufficiently strong fibre–matrix interface have been obtained, as revealed from the impact hysteresis cycles and electron microscopy damage characterisation. However, a quite significant decrease of flexural properties and an increase of unrecoverable deformation after cyclical loading were also revealed with growing impact energies, in particular passing from 12 to 16 J.