Nature‐Mimic Tough Helicoidal Composites with Aligned Short Carbon Fibers by 3D Printing

Abstract

AbstractThis work develops nature‐inspired tough helicoidal composites with aligned short carbon fibers by 3D printing. The alignment of short carbon fibers (SCF) in the composite is achieved by shear flow during 3D printing process. First, unidirectional composites with aligned SCFs are prepared with various fiber contents ranging from 2 wt% to 10 wt%. It is found that the shear strength of the unidirectional composites with the SCFs perpendicular to the shear loading is the highest at a fiber content of 10 wt%, 46% higher than that of the pristine nylon. Then, helicoidal composites with four helical angles (i.e., 0°, 30°, 45° and 90°) are prepared using 3D printing. The impact testing results show that the impact toughness highly depends on the build orientation. The impact toughness of the composites with on‐edge build orientation is significantly greater than those with flat build orientation. The greatest impact toughness of the helicoidal composites is achieved at a helical angle of 45° with a value of 31.9±4.4 kJ m−2, which is mainly attributed to misaligned fiber plane‐induced crack deflection, forcing cracks to advance in multiple planes under impact.