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.
Resin Infusion under Flexible Tooling (RIFT): a review
Abstract Increasing legislation to limit styrene emissions (mainly from polyester resin systems) into the work place has been the key factor in promoting new technology in the manufacture of fibre reinforced plastics composites. Styrene emissions can be reduced by the development of: resin systems with low styrene emission; improved ventilation and air filtering systems; closed moulding techniques. It is the final area on which this paper concentrates. RIFT is a variant of vacuum-driven RTM in which one of the solid tool faces is replaced by a flexible polymeric film. The process is known by several acronyms—in this paper it is referred to as RIFT (Resin Infusion under Flexible Tooling). Potentially a very clean and economical composites manufacturing method, the process draws resin into a dry reinforcement on an evacuated vacuum bagged tool using only the partial vacuum to drive the resin. It reduces worker contact with liquid resin whilst increasing component mechanical properties and fibre content by reducing voidage compared to hand lay-up. For higher performance composites, RIFT offers the potential for reduced tooling costs where matched tooling (RTM or compression moulding) is currently used. This paper reviews the progress of RIFT from its first development as the Marco method in 1950 to the Seemann Composites Resin Infusion Manufacture Process (SCRIMP) today. Development of the process has been slow (compared to RTM) and generally lacking in scientific rigour. Current research is reviewed and the potential for scientific development is discussed.