Abstract:
The resin flow during composite processing affects the mechanical properties and the final dimensions of the part. This study investigates resin flow velocity in autoclave processing. To measure the resin flow velocity during cure, a flow apparatus was designed and manufactured with the ability to follow the autoclave curing cycle. Resin flow tests were conducted on IM7/977-2 unidirectional laminates seeded with fluorescent polymer particles which were tracked during cure. Particle image velocimetry and particle tracking velocimetry techniques were applied individually to obtain resin flow velocity and flow pattern during cure. In addition to the peak resin velocity, corresponding time of peak velocity and flow cessation times were investigated during the test. Moreover, the effect of curing parameters such as heating rate, pressure, vacuum, and isothermal temperature on the resin flow were also studied.
For unidirectional laminate peak resin velocity in longitudinal direction was an order of magnitude higher than the peak velocity in the transverse direction. Experimental results showed that the peak velocity in longitudinal direction was very close to the maximum velocity of the resin flow test. It was observed that resin reached its peak velocity before attaining its minimum viscosity, then slowed significantly before reaching the gel point.
Finally, the resin flow study was further extended for plain weave material. Resin flow was observed in between the tow borders as well as in the tows of the specimen. In regards to plain weave material, resin peak velocities in both longitudinal and transverse directions were of the same order of magnitude.
