Direct ink writing of epoxy-based composite lattice and its strengthening and toughening mechanism

Due to the high strength and lightweight, epoxy-based composite have extremely application value in the fields of aerospace and automotive. However, the brittle nature of epoxy resin significantly hindering their application in actual engineering, it is a great challenge to improve the strength and toughness of epoxy-based composite. Herein, we develop an architecture epoxy-based composite lattice with strengthening zones and toughening zones, which are rationally assembled into a layered structure and fabricated by direct ink writing (DIW, a kind of 3D Printing). The physical and chemical properties of epoxy-based composite and filaments were characterized by rotational rheometer and optical microscope, and a universal testing machine were used to test the mechanical properties of epoxy-based composite lattice with different structure. It is indicating that the specific strength, toughness and fracture toughness of epoxy-based composite lattice were increased by 94.78%, 482% and 17.4% compared to solid composite, respectively. From the fracture surfaces and finite element analysis, it can be concluded that the strengthening zones ensure the structural strength, the toughening zones can effectively share the external deformation and prevent the crack propagation. The current research provides a new idea for the design of structural nanocomposites and a theoretical basis for the fabrication and engineering application of high strength and toughness epoxy-based composite.