A Comparison of Two Resin Flow Models for Laminate Processing

Abstract

Two well-established resin flow models for laminate processing by autoclave/vacuum degassing are compared. These are the sequential compaction and the squeezed sponge models, both based on viscous flow through porous media. A detailed examination of these models in this investigation shows that, contrary to what is com monly assumed, the fibre bed carries some of the applied pressure in the sequential com paction model. Equations for the implicit fibre bed compaction behaviour are derived, and using these equations, it is shown that the sequential compaction model is essentially a special case of the squeezed sponge model. The fibre bed pressure/compaction curve and the fibre bed permeability are identified as the two key relevant material properties. For one special case of these material properties, the squeezed sponge model predicts a se quential compaction sequence, with a roughly linear resin pressure profile, as assumed by the sequential compaction model. Using the fibre bed compaction and permeability as the primary parameters in the squeezed sponge flow model it is shown that a range of laminate compaction behaviour, from sequential to uniform compaction, can be obtained. It is also shown that the permeability controls the compaction time and the fibre bed behaviour con trols the shape of the laminate compaction response.