Processing and Evaluation of 3D-Reinforced Needled Composite Laminate

This report documents the fabrication and test of a woven glass/epoxy composite laminate that was reinforced in the through-thickness direction with aramid fibers using a needling process. The purpose of reinforcing laminated material in the through-thickness direction is to improve its delamination resistance/damage tolerance. The needled material was approximately 6.4-mm thick and was tested using American Standard Test Method ASTM standards to assess the improvements in impact response and any reductions in-plane strength, which is a typical tradeoff with 3D-reinforced stitched materials. Needled specimens exhibited 10-15% increase in effective stiffness (force-deflection response) under impact loading, and a 50% increase in compression-after-impact strength-a significant improvement in damage tolerance. Needled but non-impacted material exhibited a 9% increase in the in-plane compressive strength and a 17% increase in flexural strength, indicating at least that the needling process does not cause immediate tradeoffs in the in-plane strength of woven glass materials. Because the processing parameters were arbitrarily chosen, these experiments should be considered as proof-of-concept.