Study On Internal Heat Transfer Characteristics Of Carbon Fiber Reinforced Composite Preform

Carbon fiber reinforced composite has the advantages of light weight,high strength,fatigue resistance,corrosion resistance,good structural dimensional stability and large-area integral molding,etc.It is widely used in aerospace technology,automobile industry,wind power generation and other fields.In the forming process of carbon fiber reinforced composite,temperature affects the viscosity and fluidity of the resin,thereby affecting the sliding ability between the internal constituent phases.In macroscopically,it affects the mechanical properties of the overall material.At the same time,the woven structure of carbon fiber reinforced composite makes the internal heat transfer characteristics complex,and the uneven temperature distribution will cause various defects in the parts,affecting the forming quality and performance.According to the above problem,this paper uses a combination of numerical simulation and experimental verification to study the temperature distribution characteristics and heat transfer laws of carbon fiber reinforced composite preform under the micro and macro scales in a uniform temperature field.Furthermore,the influence of temperature on the internal pore defects and springback deformation of the preform is analyzed.In order to provide a favorable precondition and technical guidance for the production of composite material components.The main work and conclusions of this paper are as follows:(1)According to the structural characteristics of fiber bundles and resin matrix in the woven composite material,a micro-scale thermal analysis model of the carbon fiber reinforced composite preform is established using ABAQUS software.The analysis shows that the internal temperature distribution in the material is uneven due to the different thermal physical parameters of fiber bundles and resin matrix,and the fiber bundle plays a leading role.And the heat transfer rate in the axial direction of the fiber is greater than that along the radial direction of the fiber.At the same time,the temperature difference between the fiber bundle and the resin matrix decreases with the increase of temperature.(2)After homogenizing the woven composite material,a finite element model for thermal analysis of carbon fiber reinforced composite preform at the macro-scale is established.And the hot air circulation heating experimental platform is built to carry out the temperature measurement experiment for verification.The results show that in the plane,the heat transfer from the edge to the center presents a concentric elliptical distribution,and in the thickness direction,the heat is transferred sequentially between the layers.The temperature distribution in the preform is uniform and there is no heat concentration phenomenon.The temperature rise trend of the representative nodes in experiments and simulations is basically the same,and the error values are all within 10%.The simulation results are in good agreement with the experimental data,which proves the reliability of the model.(3)A carbon fiber reinforced composite preform diaphragm preforming experiment is carried out to explore the influence of temperature on the preforming quality.The results show that the increase of temperature enhances the fluidity of the resin in the prepreg,which is beneficial to the release of residual stress after molding,thereby reducing the internal pore defects inside the parts and improving the compactness.The increase of temperature is beneficial to the interlaminar slip to reduce the generation of internal stress,so that the springback deformation of the preform is reduced.The increase of temperature promotes the thickness distribution coefficient of the preform to 1 after forming,which makes the thickness distribution of the web,corner and flange position more uniform,thereby improving the forming quality and service performance of the parts.