Fracture toughness determination and mechanism for mode-I interlaminar failure of 3D-printed carbon-Kevlar composites

Additive manufacturing for continuous fiber composite exhibits great potential for the fabrication of sophisti-cated structural components. Nevertheless, interlaminar characteristics of printed parts have remained an open research question. This study aims to evaluate the mode-I interlaminar fracture property of 3D-printed contin-uous fiber reinforced composites with different interlaminar interfaces adopting carbon and Kevlar fiber. Three different double cantilever beam (DCB) configurations are considered, including carbon/carbon, Kevlar/Kevlar and carbon/Kevlar hybrid interface. It is observed that the interlaminar failure of carbon fiber was seriously affected by the void defects caused by 3D-printed. It is further found that Kevlar fiber could greatly improve the interlaminar fracture toughness attributed to the better bonding of interlayers and the denser bridging fiber. Finally, a novel idea for the hybrid interface is provided based on the characterization study of the carbon-Kevlar composites.