  In this paper, the impact behaviour of composite laminates is investigated,
and their potential for ballistic protection assessed, as a function of the
reinforcing materials and structures for three representative fibre-reinforced
epoxy systems involving carbon, glass, or para-aramid fibre reinforcements,
respectively. A multiscale coupled experimental/numerical study on the
composite material properties is performed, starting from single fibre, to
fibre bundles (yarns), to single composite ply, and finally at laminate level.
Uniaxial tensile tests on single fibres and fibre bundles are performed, and
the results are used as input for non-linear Finite Element Method (FEM) models
for tensile and impact simulation on the composite laminates. Mechanical
properties and energy dissipation of the single ply and multilayer laminates
under quasi-static loading are preliminarily assessed starting from the
mechanical properties of the constituents and subsequently verified
numerically. FEM simulations of ballistic impact on multilayer armours are then
performed, assessing the three different composites, showing good agreement
with experimental tests in terms of impact energy absorption capabilities and
deformation/failure behaviour. As result, a generalized multiscale version of
the well-known Cuniff criterion is provided as a scaling law, which allows to
assess the ballistic performance of laminated composites, starting from the
tensile mechanical properties of the fibres and fibre bundles and their volume
fraction. The presented multiscale coupled experimental-numerical
characterization confirms the reliability of the predictions for full-scale
laminate properties starting from the individual constituents at the single
fibre scale.
