Experimental impact damage study of a z-pinned foam core sandwich composite

Abstract

This paper assesses the impact damage and post-impact compression properties of a foam core sandwich composite reinforced with through-thickness z-pins. Low-speed flat-wise compression tests performed on the sandwich composite revealed that z-pins improved the elastic modulus, crush strength and absorbed energy capacity (by 260–300%). However, these property improvements do not necessarily translate into a reduction in the amount of damage suffered by the z-pinned sandwich composite under localised (point) impact loading. There was no reduction to the impact damage area or an improvement to the post-impact compression properties of the z-pinned sandwich composite at low-impact energies (when damage was confined to the impacted face skin). Z-pins were only marginally effective at reducing the impact damage when the impact energy was high enough to cause core crushing. Z-pins absorbed high-impact energy via splitting, microbuckling and fragmentation during core crushing which reduced slightly the amount of impact damage to the sandwich composite. However, this did not cause a significant improvement to the post-impact compressive stiffness and strength for most energy levels.