Research On Automatic Fiber Placement Applied In Nomex Honeycomb Sandwich Composite Material Manufacturing

Nomex honeycomb sandwich-carbon fiber panel sandwich structure composite material is widely used in aviation,aerospace and rail transportation as one of the most efficient component forms.From domestic and international research current situation can be seen:a few cases has been researched on automatic fiber placement applied in Nomex honeycomb sandwich composite material manufacturing,and hand paste molding process is still used in domestic.This paper studies the automated fiber placement process of Nomex honeycomb sandwich structure composite,for the honeycomb core lateral pressure deformation and prepreg fiber bridging and main contents include:(1)The causes and influencing factors of the lateral pressure deformation of Nomex honeycomb core are analyzed and the solutions to avoid lateral pressure deformation are explored.The causes of lateral pressure deformation of honeycomb core are analyzed from three dimensions:the anisotropy of Nomex honeycomb core,automatic placing pressure and pressure inclination.During the process of convex molding process,for strengthening the lateral pressure,the pre-bonding process of adhesive film was explored and obtained the laying pressure process window.A concave molding process was proposed to avoid the lateral pressure deformation of honeycomb core.(2)The causes and influencing factors of the prepreg fiber bridging in honeycomb core are analyzed.And the solution to reduce the prepreg fiber bridging is explored.The single-factor experiment and orthogonal experiment design were carried out for the influence factors of the fiber bridging.The main factors and its influence order of bridge size are as following: laying pressure,taws tension and roller modulus.The best process plan for reducing the size of the bridging was proposed and the concave module tooling is improved to avoid the fiber bridging.(3)According to the shape of honeycomb core material and the accurate design of the preloading thickness,the die tooling is machined.For the main influencing factors for the girder bridge-laying tension,the technique of local zero tension laying is explored: an additional decision processing is made for the automated laying trajectory point and the length of the fiber feeding was fitted with a cylinder spiral,the taws zero-tension laying technology is realized.A more complicated bridge over a 45-degree berth,finite element analysis is used to determine the roller width of inner skin automatic laying.(4)In order to study the influence of fiber bridging on final product quality,and verifies the effect of the overcast tooling to avoid the lateral pressure deformation and the fiber bridging.Two kinds of tooling are used to complete the automatic wire laying verification,the surface quality?slanting area on slanting position and bending mechanics of two kinds of process were contrasted and analyzed,and the forming process of the composite material of the Nomex honeycomb sandwich was determined.