Experimental and numerical study of coupled gas and resin transport and its effect on porosity

Partially-impregnated prepregs are three-phase systems consisting of fiber, resin, and gas. During processing, one of the main goals is to evacuate the gas and infiltrate the space left behind with liquid resin to minimize porosity. Most work in this area has focused on gas and resin transport independently, and the interaction between resin and gas transport in these systems is currently poorly understood. The current study examines this interaction by evaluating the resulting laminate porosity as a function of different bag and applied pressures during debulk and cure. Experimental results show that resin flow can promote gas evacuation without the need for hard vacuum under the bag. An explicitly-coupled gas–resin transport model is developed on the basis that fiber-bed porosity is a function of resin infiltration. The model extends previous work in the area and is shown to predict the experimentally measured porosity under different pressure situations with acceptable accuracy.