Studies on impact damage resistance of affordable stitched woven carbon/epoxy composite laminates

This paper discusses the response of seven layer plain and satin weave carbon fabric reinforced composites fabricated using low-cost Vacuum Assisted Resin Infusion Molding (VARIM) process under low-velocity impact loading. Both stitched and unstitched laminates were tested at energy levels ranging 5-50 J using an instrumented drop-weight machine. A 3-cord Kevlar thread was used to stitch the laminate in two orthogonal grid patterns each at a 6 mm pitch: one with 25.4 mm and the other with 12.7 mm grid. Damage due to impact loading was evaluated through ultrasonic nondestructive evaluation (NDE). Results of the study showed the effectiveness of stitching in containing the damage size with 12.7 mm grid stitch samples exhibiting the least damage. Further, satin weave fabric composites exhibit better impact resistance as compared to plain weave fabric composites.