Mitigating the weak impact response of thin-ply based thin laminates through an unsymmetrical laminate design incorporating intermediate grade plies

Artikel i vetenskaplig tidskrift, 2019

With aeronautic industries focussing on thinner structures and reducing manufacturing costs, recent research has been dedicated to the impact and post impact response of thin laminates (<2 mm) made of textile fabric composites. A recent study revealed that thin laminates based on thin plies exhibit extensive fibre failure and a reduced compression after impact strength. To mitigate this weakness, we propose a novel laminate concept based on combining plies of different thicknesses in an unsymmetrical configuration (intermediate grade plies are located only at the bottom of the laminate, i.e., the non-impacted face). C-scan inspection on impacted and quasi-statically indented specimens, allowed the damage sequence of the proposed unsymmetrical hybrid laminate to be compared with that of the thin-ply baseline. The hybrid laminate with intermediate plies at the bottom, delayed and reduced the fibre damage, decreased the projected delamination area and led to a 30% increase in the compression after impact strength in contrast to the thin-ply baseline laminate.