Viscoelastic response of dry and wet fibrous materials during infusion processes

The deformation response of fibrous materials to transverse compressive forces plays an important role in the Liquid Composite Molding (LCM) processes. The objective of this study was to characterize this response and to create a model of the response for inclusion in simulations of LCM processes. A series of compression tests were carried out on both dry and resin impregnated samples. A model of fibrous material deformation was developed, incorporating the observed viscoelastic response and the difference in behavior between the dry and wet samples. The same model is used for both compaction and relaxation phases, and matches well experimental data over a range of fiber volume fractions and compression speeds.