3D printing process for continuous fibre reinforced composites with variable deposition direction

Continuous fibre reinforced polymer (CFRP) have a distinctive anisotropic character. In traditional 3D printing processes, deposition direction cannot be adjusted. As a result, the performance of CFRP parts is deficient in the fixed direction. To address the issue, this paper proposes a variable deposition direction (VDD) 3D printing process for CFRP. The process optimises the mechanical properties of the moulded part by adjusting the direction of deposition. The principles and processes of the VDD 3D printing are described in detail. Then, using the hollow cylinder as an example, a mathematical model of the variable deposition direction structure is developed, and subsequent simulations is conducted to evaluate its mechanical properties. In the experimental part, the composite material used has a fibre content of 20% and consists of PETG and carbon fibres. The VDD hollow cylindrical parts have been printed to verify the feasibility of the process. And performance testing experiments were carried out on a variety of test specimens of different structures with VDD. The results show that adjusting the deposition direction of the CFRP can greatly improve the tensile properties of hollow cylinder. The tensile properties of a suitable structure with VDD were improved by a factor of 69.4 compared to a single deposition direction structure. And the actual tensile situation is consistent with the simulation. To summarise, the proposed method can effectively solve the defects of the traditional process and optimise the mechanical properties of the moulded parts.