Impact Resistance of 3D-Printed Continuous Hybrid Fiber-Reinforced Composites.

Improving the resilience of 3D-printed composites through material extrusion technology (MEX) is an ongoing challenge in order to meet the rigorous requirements of critical applications. The primary objective of this research was to enhance the impact resistance of 3D-printed composites by incorporating continuous hybrid fibers. Herein, continuous virgin carbon (1k) and Kevlar (130D and 200D) fibers were used with different weight and volume fractions as reinforcing fibers to produce hybrid and non-hybrid composites for impact resistance testing to obtain energy absorption with different impact energies: 20 J, 30 J, 40 J, and 50 J. Moreover, 0°/90° fiber orientations were used. Hybrid composites with combinations of PLA + CF + 130D KF and PLA + CF + 200D KF showed higher impact resistance, less damaged areas (71.45% to 90.486%), and higher energy absorption (5.52-11.64% more) behaviors compared to PLA + CF non-hybrids. CT scan images provided strong evidence to resist the fracture and breakage patterns, because the stiffness and elongation properties of the fibers acted together in the hybrids specimens. Furthermore, positive hybrid effects of the PLA + CF + KF hybrids also showed an ideal match of toughness and flexibility in order to resist the impacts. In the future, these hybrids will have the potential to replace the single type of composites in the fields of aerospace and automobiles.

Spatial 3D Printing of Continuous Fiber-Reinforced Composite Multilayer Truss Structures with Controllable Structural Performance.

Continuous fiber-reinforced composite truss structures have broad application prospects in aerospace engineering owing to their high structural bearing efficiency and multifunctional applications. This paper presents the design and fabrication of multilayer truss structures with controlled mechanical properties based on continuous fiber-reinforced thermoplastic composite 3D printing. Continuous fiber composite pyramid trusses fabricated by 3D printing have high specific stiffness and strength, with maximum equivalent compression modulus and strength of 401.91 MPa and 30.26 MPa, respectively. Moreover, the relative density of a truss structure can be as low as 1.45%. Additionally, structural units can be extended in any direction to form a multilayer truss structure. Structural performance can be controlled by designing the parameters of each layer. This study offers a novel approach for designing a multifunctional multilayer truss structure, a structure with low-density needs and unique load-bearing effects.