Research On Forming CFRP Components And Controlling Porosity With HP-RTM Process

Carbon fiber reinforced composite(CFRP)has been applied in important structural parts with the advantages of light,high-modulus and high-strength compared with traditional metal materials.Under the background of the automobile body's lightweight becoming an inevitable trend,High Pressure Resin Transfer Molding Process(HP-RTM)with a relatively higher volume fraction,higher molding efficiency,shorter molding cycle,more excellent surface quality and easier to automate than other molding processes becomes a research hotspot for automobile body structure technology.In this thesis,the effects of material parameters and process parameters on the parts porosity were studied,including the determination of fiber permeability,the injection flow rate and the injection pressure.The main results of this study are as follows:(1)Based on the test method of fiber fabric permeability,a test model was established and a permeability test device was designed,which has the merit of continuously compressing the fabric and a small edge effect in the process of flow.The permeability of different types of fabry were tested by the test device,and the relationship between the volume fraction and the permeability was obtained by using the Carman-Kozeny model.Finally,the reliability of the test resuts was verified by the comparison of simulation and experiment.(2)Combined the filling cycle with porosity control theory and based on the flow simulation software platform,,the influence of the injection and the injection mode on the porosity of B-pillars of automobile was studied in HP-RTM.In this thesis,the schemes of three injection port distribution and the two injection modes were designed,namely,single injection,double injection and three injection.The injection modes were constant pressure injection and constant flow injection.Then,the results of the pore distribution of different injection schemes were compared,and the process parameters are optimized for the best quality parts.(3)The results of the distribution of pore under different process parameters were studied by the combination of the experiment and simulation.The porosity of the workpiece was measured by ultrasonic scanning and metallographic microscopy.The result shows that the simulation model established in this paper can effectively predict the pore distribution of the workpiece in the HP-RTM process.(4)In this thesis,the influence of porosity on the mechanical properties of the workpiece is obtained,which is of great significance to the performance evaluation of the automobile parts.