Compressive properties and failure mechanisms of 3D-printed continuous carbon fiber-reinforced auxetic structures

3D printing of continuous carbon fiber-reinforced (CCFR) composites is an innovative and promising fabrication technique that meets the booming demands of lightweight and structural diversity in advanced transportation industries. In the present work, 3D printing of CCFR composites is introduced to design and fabricate auxetic structures with four Poisson's ratios. The compression characteristics of the 3D-printed CCFR auxetic structures are experimentally investigated under quasi-static loading. The characterization of fracture microstructures and the finite element simulation are carried out to go deeper into the compressive behaviors and failure mechanisms. Moreover, the compressive characteristics of the auxetic structures under diverse Poisson's ratios are analyzed based on the stress-strain curve, energy absorption and failure modes. The results reveal that the transformed configuration significantly affects the compressive properties and deformation behaviors under different Poisson's ratios. The 3D-printed CCFR auxetic structure with Poisson's ratio of -0.531 possesses the preferrable transformed configuration, leading to the highest specific energy absorption (SEA, 2.302 Jg-1). The bend-induced damage evolves from the whitish resin to the complete breakage of fibers, which is the dominant failure mode of 3D-printed CCFR auxetic structures. The research plays a vital guiding role in the structural design and engineering applications of 3D-printed CCFR auxetic structures with desired mechanical properties.