Mechanical properties and failure behavior of 3D printed thermoplastic composites using continuous basalt fiber under high-volume fraction

Continuous basalt fiber (CBF) is an outstanding inorganic fiber produced from nature, which has a wide range of applications in the field of armor protection of national defense military. However, the mechanical response and failure mechanism of 3D printed CBF reinforced components are still not well understood. Here, the 3D printing thermoplastic composites with high volume fraction CBF have been successfully prepared by fused deposition modelling (FDM) method. The effects of fiber printing direction and polymer matrix type on the tensile and flexural properties of the 3D printed composites have been explored, and the detailed failure morphology has been characterized using scanning electron microscopy and optical microscopy. It was found that under high fiber volume fraction, 3D printed CBF reinforced polyamides (PA) composites have the best ability to maintain material integrity of the composites, followed by acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS). Besides, the results from rule of mixtures can accurately predict the longitudinal Young's modulus of the 3D printed specimens, but there exists a large discrepancy for the prediction of the tensile strength. The microstructure analysis shows that the failure modes of 3D printed composites mainly include fiber debonding, fiber pull-out, stress whitening and matrix cracking.