Study On The Vacuum Assistant Resin Infusion Process

Recently, Vacuum-assisted Resin Infusion (VARI) process has become one of the increasingly popular methods for manufacturing composites in the aerospace industry. In order to avoid the trial and error, the computer model should be applied to simulate the filling process. However, due to the flexible vacuum bag instead of rigid upper mold, there are some differences between RTM and VARI process.The significant influence factors on VARI process are investigated, such as the compaction, spring-back behavior and permeability. The results could be used to ensure reliable simulation and also help to select the proper textile reinforcements in the VARI process.The relations between bundle size, number of layers, textile structures and the fiber volume fraction under compaction are investigated in this paper. The further compaction and spring back behavior caused by the lubrication and unloading mechanism after the resin impregnation is also been studied.The deformation of textile reinforcement under compaction would change the shape and size of voids inter and intra the fiber bundles. Laminates made by epoxy resin with different fiber volume fractions have been analyzed by the micrographic structures. The relation between the fiber volume fraction and permeability is predicted.Under certain processing conditions such as low injection pressure and high fiber volume fraction, the microscopic flow of resin tow and the fiber wet out can considerably influence the overall flow. A rectilinear mold with a transparent upper mold was made and used in the permeability tests. The permeability and capillary pressure of the warp knitted preforms with different fiber volume fraction and lay-up angle were test at various injection pressures.Specimen were made by VARI process, RTM and hand lay-up The tensile, bending, shearing and compaction properties of them have been tested.