Modelling matrix injection through elastic porous preforms

This study deduces a new model aimed at simulating injection moulding processes under isothermal conditions and in situations in which infiltration generates deformations in the reinforcing network, both in the solid preform part which is still dry and in the part that has already been infiltrated. As a by-product the model allows the stress and deformation states in the solid preform to be monitored. The coupled flow/deformation problem in the fully infiltrated region and in the uninfiltrated region is then formulated with the proper evolution equations for the boundaries delimiting the two domains and with the relative boundary and interface conditions. The stationary configurations for the one-dimensional problems characterized by given infiltration velocity or pressure are analytically determined for general elastic stress-strain and permeability-volume ratio relations. The unsteady problem is solved numerically, putting in evidence the influence of the deformations on the bulk flow and on the propagation of the advancing front. (C) 1997 Elsevier Science Limited.