Due to their inherent weakness in thickness direction, laminated fiber reinforced composites are susceptible to undergo large delamination damage when subjected to transverse loading. Low-velocity impact loading is one such case. Low-velocity impact occurs due to tool-drops during manufacturing, maintenance, and service, runway debris during landing and takeoff and hailstorm. In the current work an effort is made to improve the transverse strength by providing 3D reinforcement in the form of pins and stitching the laminate in thickness direction. Laminates were made of S2-Glass/Vinyl Ester. Specimens of size 3 × 4 inch were subjected to drop-weight impact at energy levels of 20, 31 and 41 Joules. The impacted panels were subjected to vibration tests to determine the stiffness loss through vibration based frequency response function (FRF) measurements. Effect of impact damage on interlaminar shear strength was studied. Results indicate that there is considerable improvement in damage tolerance due to 3D reinforcement.

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