Simulation of the Vacuum Assisted Resin Transfer Molding Process
Abstract : A process model that includes the coupled phenomenon of resin flow and preform compaction was developed and used to simulate resin infiltration of a fibrous preform using the vacuum-assisted resin transfer molding (VARTM) process. Flow of resin through the distribution medium and preform were modeled as flow through porous media. The finite element/control volume method was used to calculate the infiltrating fluid pressure distribution and track the progression of the flow front. The simulation results were compared with data obtained during infiltration of a carbon fiber preform with an epoxy resin. The parameters measured include the flow front location, resin pressure, and preform thickness change. With accurate inputs, the flow front locations and resin pressure distribution can be accurately predicted. The predicted transverse displacements do not agree well with the experimental measurements. The reasons for the differences are discussed, and further investigations are recommended to develop a more accurate compaction model.
Investigation on Dimensional Accuracy for CFRP Antenna Reflectors Using Autoclave and VARTM Processes
The carbon fibre reinforcement polymer (CFRP) is widely used in space applications, automobile industries, aerospace and sports equipment because of good specific properties over conventional metals and alloys. Autoclave processing is one of the best manufacturing techniques to achieve high-dimensional accuracy for complex-shaped component. But, due to high initial and processing cost, vacuum-assisted resin transfer moulding (VARTM) is the alternative manufacturing method. In this research paper, CFRP antenna reflectors have been manufactured using autoclave process and VARTM manufacturing process to evaluate dimensional accuracy. The part thickness of laminate and layup orientation has been considered as a processing parameter in reflector manufacturing. The dimensions of the inner surface of the manufactured reflectors have been measured using 3D scanning techniques at the different locations. The deviation between theoretical CAD model and reflector dimensions at each location provides dimensional inaccuracy for the fabricated reflectors. The investigation on the dimensional inaccuracy of cured reflectors manufactured using the autoclave and VARTM manufacturing techniques has been carried out and the percentage difference has been found within the acceptable limit.
The Consolidation of Laminate Composites
A general mathematical model wich allows for three dimensional flow, and one dimen sional consolidation of the composite, is developed. The model assumes that the fibers make up a deformable, nonlinear elastic network. The resin flow is modelled using Darcy's Law for an anisotropic porous medium, with a resin of time varying viscosity. The general case is then solved for two important molding situations: 1) Compression Mold ing, and 2) Bleeder Ply Molding.