Preparation and characterization of three-dimensional braided carbon/Kevlar/epoxy hybrid composites

Though unidirectional, short, and laminated hybrid composites have been extensively investigated because of their wider range of properties than non-hybrid composites, literature on three-dimensional (3-D) braided hybrid composites is very limited. In this work, Kevlar fibers were hybridized to carbon fibers to prepare 3-D carbon/Kevlar/epoxy composites with various carbon to Kevlar fiber volume ratios in an attempt to find alternative materials for osteosynthesis devices. The flexural, shear, and impact properties of the 3-D braided hybrid composites were measured in order to investigate the effect of carbon to Kevlar ratio and evaluate hybrid effects. In addition, residual flexural strength was tested for the impacted samples and the damage tolerance was assessed. Our experimental results revealed the existence of positive hybrid effects on the shear and flexural strengths flexural strain for the 3-D braided composites. The absorbed energy and flexural strength retention of the 3-D braided hybrid composites were found to decrease with relative carbon fiber content. It was shown that hybridizing ductile 3-D braided Kevlar fabric with stiff carbon fabric could result in the hybrid composites with flexural strength comparable to the all-carbon composite and impact damage tolerance superior to the all-Kevlar composite.