Abstract:
Manufacturing high-performance fiber reinforced plastics (FRP) products within short
manufacturing cycles is a significant challenge in the industry. This study investigated the
application of resin spray-compaction method for long fiber reinforced plastics (LFRP)
manufacturing, expecting improved productivity and product quality at low cost.
Computational fluid dynamics (CFD) modelling was applied to study the spray, deposition,
and compaction phases of the process. The composite components used for the study comprised
unsaturated polyester resin and glass fiber. The validation of CFD results for each phase of the
process was conducted using techniques of Phase Doppler Anemometry (PDA), camera
imaging, press works, and other experimental works. The void and fiber volume fraction (FVF)
of laminates manufactured by the process were also inspected using x-ray computed
tomography (CT) and image analysis techniques. The findings from the spray deposition study
indicated a concentration of smaller resin droplets at the center of the spray plume, while larger
droplets were more abundant towards the periphery. When examining the velocity distribution
in reverse, it was observed that the speed was higher at the center and lower at the periphery.
The distribution of film thickness on the deposition surface was found to be variable, exhibiting
thicker and wavy layers around the center, while experiencing a sharp decline towards the
periphery. The compaction results revealed significant variations in flow speed of resin
between the radial and thickness directions of the preform. The flow behaviour was notably
affected by the porosity and permeability of the preform. It was observed that a lower
compaction speed had a significant impact on reducing the presence of voids within the
produced laminates. At a compaction speed of 1mm/min, the void fraction decreased to as low
as 1.5%. On the other hand, the compaction pressure above the compaction speed exhibited a
notable influence in determining FVF of the laminate, offering the potential to achieve FVF up
to 72%. Based on the study findings, it can be concluded that the resin spray and compaction
method can be effectively applied in LFRP manufacturing, and the CFD models developed in
this study can be implemented in effectively predicting the process characteristics. The method
was proved of having shorter manufacturing time, and reduced product defects.
Key words: spray modelling; deposition; porous flow; compaction; fiber; fiber volume fraction; resins; voids.