Design of Z-fiber Guiding Needle for Composite Material Preform with Large-Thickness and High-Density

Traditional carbon fiber reinforced carbon matrix composites are mostly two-dimensional laminated structures with low interlayer properties. Z-fiber reinforcement technology can improve the properties of composites in the thickness direction. However, the low axial modulus of Z-fiber results in insufficient stiffness, and its implanting in large-thickness preforms is susceptible to buckling due to heavy resistance. The existing Z-fiber implantation techniques are challenging to realize the Z-direction reinforcement of large-thickness and high-density preforms. Therefore, this paper proposes a method of using hollow tubes to guide Z-fiber implantation into preforms and puts forward an improved solution for the issue of buckling during the insertion of hollow tube into the preform. A cutting edge was designed for the hollow tube, and a metal rod was utilized to provide support. The enhanced hollow tube was named "Z-fiber guiding needle." A mechanical model of the Z-fiber guiding needle inserted into the preform was established to optimize needle parameters. Then Abaqus software was used to study the strength and stiffness of the needle, as well as analyze its stability. Finally, experimentally verifies the Z-fiber guiding needle. The final results show that the strength, stiffness, and stability of the designed Z-fiber guiding needle can meet the requirements of implantation. This proves the designed method is correct and feasible, and provides a theoretical basis for the design of ultra-long needles used to guide Z-fiber implants into large-thickness, high-density composite material preforms.