Experimental And Simulation Study On Vacuum Assisted Resin Infusion Process

VARI(Vacuum Assisted Resin Infusion) is an advanced composite material manufacturing method which was developed based on RTM (Resin Transferring Molding).The principle of VARI is as below:Firstly, put the perform in the single-side rigid mold, then cover the mold with soft vacuum bag and seal it, eliminate the air from the mold cavity through vacuum pump, then the resin will be driven into the mold cavity by the vacuum negative pressure. This method can cut the cost, reduce wastage, improve product quality and is very suitable for manufacturing large scale products.There are many factors affect the process of VARI, such as operating temperature, the rheological property of resin, the structure and laminated modes, vacuum degree, the position and quantity of inlets and outlets and so on. For this project, only some main factors were selected and studied in detail, these factors are the rheological properties, laminated modes, the design of inlets and outlets and so on. Through the combination of experiments and simulation, the effects on VARI process from those factors were seriously studied, through which useful conclusions and proper optimization were made to guide the practical VARI process.About the VARI process, this project mainly did the following study:1) Searching and reading literatures which were relative to VARI process, learning the principle, characters and main affecting factors, summarizing the research and application status, and finding the main problem of VARI.2) Considering the requirements on resin properties from VARI, a kind of UPR resin-DS326PT-1were selected and studied. Through measuring the viscosity variation under dynamic and constant temperatures, an engineering resin model was established. The mold can predict the resin viscosity variation under different temperature and time, also it can predict the low resin viscosity window which was meaningful for guiding the VARI process.3) Study the main measurements methods and affecting factors of permeability, the single-direction method and radial method were mainly studied in detail. Analyzing the theoretical base, calculation methods and experimental steps, and measured the permeability of glass fiber mats and single-direction glass fabric. Comparing the measurement results by the two different methods.4) Study the effects on VARI process caused by layup methods. By designing and carrying out a series of experiments, those factors including number of layers (thickness), laying angle, the length of HDM (High Distribution Media) were studied, through comparison of the serial experiments, the way how those factors affect the VARI process were concluded.5) Design several different infusion schemes for two kinds of composite material products which are asymmetrical cross planet and automobile chassis. Firstly, the schemes were designed differently mainly from the position, shapes and quantities of inlets and outlets. By simulating the serial resin infusion process of different schemes, analyzing the simulation results including the resin filling flash, the resin front shapes, the filling time distribution and pressure distribution which were output by PAM-RTM software, the best and most suitable infusion scheme were selected according to different requirements. Verifying the simulation by carrying our correspondent experiments and compared the experimental and simulation VARI process, drawing some useful conclusions which are useful for practical VARI process.