Research On Key Technologies Of 3D Printing Of Continuous Fiber-reinforced Composites

Continuous fiber-reinforced thermoplastic resin composites have superior mechanical properties and good designability,and their application range in the manufacturing field is becoming more and more extensive.3D printing has the advantages of not relying on mold manufacturing and high shaping freedom,etc.,and its application on composites molding is expected to realize the integrated molding of lightweight and complex structural parts.Aiming at the 3D printing technology of continuous fiber-reinforced composites,this thesis has carried out research on the 3D printing device of continuous fiber-reinforced composites and basic process of 3D printing,designed a printing nozzle of continuous fiber-reinforced thermoplastic resin composites,and carried out the 3D printing basic process experiment of continuous fiberreinforced composites,and simulated the effect of the fiber printing path on the mechanical properties of the part.All the purpose is to improve the quality of the 3D printed composites parts,which is of great significance for exploring the application field of 3D printing of continuous fiber-reinforced composites.First,the structural design of the continuous fiber-reinforced composite 3D printing nozzle was carried out.Based on the fused deposition molding technology,a 3D printing nozzle is designed.The finite element analysis software was used to carry out temperature field simulation and flow field simulation analysis.According to the simulation results,the structure type and structure parameter of 3D printing nozzle were optimized.The process of continuous fiber-reinforced composite 3D printing was simulated and analyzed,thus theoretically verified the feasibility of 3D printing manufacturing of continuous fiber-reinforced composites.Secondly,a 3D printing device of continuous fiber-reinforced composites and a continuous fiber prepreg device were designed.The frame,motion mechanism and control system of the printing device were designed.Based on the installed 3D printing device of continuous fiber-reinforced composites,the printing basic process experiment research was carried out.The experimental results showed that the impregnation effect of the fiber in the nozzle is poor.According to the analysis of the continuous fiber and resin matrix impregnation mechanism,a continuous fiber prepreg device was designed based on the solution impregnation method.Finally,the mechanical properties of 3D printed continuous fiber-reinforced composites were simulated.The static structural and eigenvalue buckling simulations of unidirectionally printed laminates and spiral-printed laminates were analyzed.The effects of the two printing paths on the mechanical properties of the laminates were compared.The results showed that the overall stiffness of the laminates obtained by the spiral printing was better than that of unidirectional printed laminate;based on the characteristics of 3D printing of continuous fiber-reinforced composites,three different printing paths were designed for the wing made of continuous fiber-reinforced composites,which correspond to three different wing.By comparing their total deformation and stress under the load of aerodynamic and structural mass,the results showed that when the fiber orientation is along the direction of the load,the corresponding wing structure can meet the design requirements.