Research On Strength And Infiltration Of The Flax Fiber Structure Through The Vacuum Assisted Resin Transfer Molding Technology

The flax fiber composite material has become one of hot spots in all fields of applied research for its less energy consumption, low cost and renewable characteristics. The Vacuum Assisted Resin Transfer Molding(VARTM) technology of the flax fiber structure is the important factor influencing the structure mechanical properties, through VARTM molding technology, we can optimize the composition of the flax fiber structure, reduce the defect formation, thus improve the mechanical properties of the flax fiber structure.The main goal of this paper is to improve the mechanical properties of the flax fiber structure;through introducing Kelly-Tyson model, we can predict the flax fiber structure tensile strength; and according to the defects forms mechanism; then using numerical simulation method to study the influence of the tensile strength and the infiltrating features of the flax fiber structure on the fiber volume fraction, beam spacing, temperature and other molding parameters; meanwhile, using ultrasound technology to optimize the flax fiber structure forming process; all of these have the guide meaning to the preparation of flax fiber structure.With the method of numerical simulation, we study the VARTM molding technology defects formation mechanism, then analyze for the various factors affecting the formation of defects and different defect types; combine of flax fiber structure defect formation mechanism and the single variable method, through numerical simulation and computational fluid dynamics software to respectively simulate various factors of influence on the strength of the flax fiber structure, take the flax fiber as porous media region, consider the problem of multiphase flow, set up the resin’s infiltration mathematical model in the flax fiber bundles and between the flax fiber bundles.Resin in the fiber bundle of infiltrating uses the multiphase porous medium model in infiltrating behavior description, resin between the fiber bundle uses pure fluid infiltration behavior description, and the coupling between the two areas use the single area method. This paper respectively does some numerical simulation for the influence law on the filling period about processing parameters on the resin infiltration, and gets the changing rule of the resin infiltration front about the inlet pressure, fiber bundle spacing and permeability to the in the fiber bundle and between the fiber bundle, frontiers of infiltration in the fiber bundle and the gap between the fiber bundle is proportional to the fill speed, the distance between the beam.It is applied by the ultrasound technology to reinforce the flax fiber structure VARTM forming infiltration process, we can introduce the analysis of the characteristics of the flax fiber, and set up the flax fiber structure strength prediction model, predict the flax fiber tensile strength according to the fiber volume fraction variable, then compare the predicted values and the actual values, finally.and analyze the influence of ultrasonic on the viscosity of the epoxy resin matrix and the flax fiber structure tensile strength.Research shows that:the flax fiber structure intensity can be significantly improved by ultrasound; ultrasound frequency and processing time has a significant influence on the tensile strength of the flax fiber structure.