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 sophisticated 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 continuous 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.