| The 3D integrated woven spacer composite(IWSC)material is a new type of composite material of rapid development,which is gradually occupied the use range of traditional honeycomb.But at present,the main processing method of the facesheet-reinforced 3D integrated woven spacer composite component(FIWSC)is to solidify the hollow sandwich core firstly,and then connecting the reinforcing panel and the hollow sandwich with adhesive bonded technology.This method has the following disadvantages: 1)time-consuming;2)high energy consumption;3)non uniform resin distribution resulting the glue enrichment below layer;4)not easy to keep the verticalness of piles.The technology of curing the FIWSC by microwave was put forward and studied.The main research results and innovation are summarized as follows.A thermo-chemical model for the microwave curing of FIWSC was established.Three dimensional Fourier’s equation including heat conduction and heat source of microwave absorption and resin curing reaction was given.According to the structure characteristics of FIWSC,calculation formulas of component density,specific heat and thermal conductivitives in X,Y,Z direction were derived.Parameters mentioned above were substituted into the three-dimensional Fourier heat conduction equation,so that thermo-chemical model for the microwave curing of FIWSC was established.It provides theoretical guidance not only for simulation of microwaving curing of FIWSC,but also for optimization of the process parameters of microwave curing process of FIWSC.In view of the present situation of the extensive application of E51 / DDS resin system in aerospace industry,a thermo-chemical model of microwave curing of E51 / DDS system FIWSC was established.The curing exothermic curves of E51 / DDS were measured by DSC experiments at different heating rates.By fitting the experimental data to calculate the parameters of activation energy,preexponential,reaction order and diffusion coefficient function of curing kinetics equation for E51 / DDS system,which can accurately describe the curing characteristics of E51 /DDS system.The curing kinetics equation,the density and specific heat parameters of E51 / DDS system were added to the general thermochemical model,and then the thermochemical model of microwave curing of E51/DDS system FIWSC is obtained.The microwave curing process of E51/ DDS FIWSC was calculated and analyzed by Abaqus finite element software.The effects of key parameters on the temperature field and curing degree field are obtained.The influence of key parameters on the curing uniformity and mechanical properties of E51 / DDS FIWSC was studied by a series of experiments.According to the agreement between experimental results and finiteelement analysis,the validity of the established thermochemical model was indirectly verified.In this paper,a new processing method using microwave for FIWSC was proposed,which not only could ensure that the core column is upright but also could be processed efficiently.The experiment results indicate that this method is more helpful to improve the quality and reduce the energy consumption of microwave curing than that of the conventional microwave curing.Compared with the traditional two-step bonding curing method,the processing time of new processing method proposed above is shortened obviously.A new type of multi-layer heterogeneity composite die was proposed,which was a middle pull-out sandwich structure.The upper mold is made of light material with high wave permeability,high thermal conductivity and low expansion coefficient,while the middle die is made of light material absorbing microwave heat or wave transmission.The bottom die is made of high wave permeability and high heat insulation lightweight material with high ratio and strength.The efficiency of microwave energy utilization is increased,the energy loss is reduced,the generality of die is increased,and the geometric deformation and residual stress of components are reduced. |
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