Research On Technologies Of Continuous Fiber-reinforced Composites 3D Printing For Lattice Structure Manufacturing

Structural lightweighting is a constant theme,and structures and materials with lighter weight and heavier load have been the focus of research in fields such as aerospace,automotive manufacturing and marine vessels.From the structural point of view,the three-dimensional lattice structure represented by pyramidal lattice is considered as one of the lightest and high-strength potential structures.From the material point of view,lightweight and high-strength continuous carbon fiber reinforced thermoplastic resin matrix composites have become the best choice for aerospace materials.The composite lattice structure is the product of combining lightweight structure and lightweight material,which pushes the level of structural lightweight to a whole new level.However,due to the complexity of its structure,the manufacturing technology related to composite lattice structure has become a bottleneck that restricts its wide application.In recent years,continuous fiber-reinforced composite 3D printing technology has shown good manufacturing flexibility,demonstrating the molding potential and wide application of composite lattice structures.In this paper,the related continuous fiber 3D printing technology is investigated with a typical composite 3D lattice structure.Based on the analysis of the molding process of continuous fiber 3D printing lattice structure,this paper proposes a screw extrusion 3D printing nozzle design,completes the construction of continuous fiber 3D printing equipment for composite lattice structure,completes the construction of the corresponding control system of the equipment,the development of the electrical system,and the construction of 3D printing auxiliary equipment,and obtains good results.In this thesis,the parametric modeling of tetrahedral,pyramidal and six-branch lattice configurations is constructed,and the lattice structure lightness index is characterized by relative bulk density;a lattice structure flat-pressure theoretical mechanical model is established,and the lattice structure flat-pressure strength prediction formula is derived.Based on the Cartesian coordinates,the lattice structure forming trajectory is designed and the key technology of lattice structure forming is studied.In this thesis,the key process factors of continuous fiber 3D printing lattice structure forming were explored in combination with equipment,and tetrahedral,pyramidal and six-branch lattices were prepared and tested for flat-pressure mechanical properties and failure form analysis.Among the different types of lattice cores,the pyramid lattice core has the best flat compressive strength with a load to mass ratio of 276.14 N/g.Among the pyramid lattice cores with different branch angles,the 45° core has the best flat compressive strength of 0.459 MPa.The experimental results fit well with the theoretical prediction model.