Microstructural effects in viscous flow through fibre preforms

摘要

Flow in fibrous porous media is important in a number of applications involving infiltration of a molten (or, generally, liquid) material into fibre preforms. Example applications in the field of polymer composites involve resin transfer moulding (RTM), structural reaction injection moulding (S-RIM) and autoclaving [1-3]. In metal-matrix-composites formed through melt infiltration, the arrangement of the fibres in the preform has been shown to affect microsegregation [4]. Even in casting of un-reinforced alloys, macrosegregation has been shown to be significantly affected by the flow into the mushy zone, where melt convection inthe inter-dendritic space is impeded by a solid dendritic network [5]. Such flows are usually modelled using Darcy's law; the success of this approach depends in a crucial manner on the quality of the data available for the effective permeability of fibrous porous media. To date, there has been considerable research activity in this area [1-3].