This paper investigates the effect of transverse impact loading on the in-plane shear behaviour of two laminate configurations. The extensive experimental studies consider a pure carbon laminate (type 1) and a novel X-shaped carbon/glass laminate (type 2). The results establish that all three graduated impact energy levels (5J, 7.5J and 10J) induce through-thickness matrix cracking, fibre breakage and delamination in the type 1 laminate. However, the use of glass plies in the type 2 laminates resulted in only matrix cracking towards the impacted surface and limited through-thickness damage. Post impact, both laminate types demonstrated lower buckling load, failure load and stiffness. The reduction in buckling load of the type 1 specimens was greater than that of the type 2 specimens. However, the reduction in failure load of the type 1 specimens was less than that seen in the type 2 specimens. Both laminate types demonstrated a stable post-buckling equilibrium path. A novel machine vision technique based on polarisation imaging was successful in standardising the process of identifying the damage location/size for the type 1 laminates, but not for the type 2 laminates. This was due to the inclusion of surface glass plies which, unlike carbon plies, do not polarise light at the point of reflection.
Damghani, M., Saddler, J., Sammon, E., Atkinson, G. A., Matthews, J., & Murphy, A. (2023). An experimental investigation of the impact response and post-impact shear buckling behaviour of hybrid composite laminates. Composite Structures, 305, 116506. https://doi.org/10.1016/j.compstruct.2022.116506