IMPROVING FRACTURE-RESISTANCE OF LAMINAR TEXTILE COMPOSITES BY 3RD-DIRECTION REINFORCEMENT

The fracture behavior of multidirectional laminar composites was inves tigated. Two- and three-dimensional composites were fabricated and tes ted for this purpose. The effects of third direction fibers on composi te mechanical properties were examined. Effects of fiber orientation, stitch density and configuration on resistance to crack propagation an d the suppression of delamination were studied. Damage resistance, fle xural and shear strength were investigated as a function of distributi on of the third direction fibers. The effects of fiber damage due to s titching on the mechanical properties of composites were examined. A n ew stitching method was developed which successfully eliminated the fi ber damage. Delamination was reduced and shear strength and impact ene rgy were increased in properly stitched 3-D composites.