Compressibility and flow permeability of two‐dimensional woven reinforcements in the processing of composites

Abstract The processing of composites under pressure is described by a viscoelastic model in which the pressure acts on the fibers in an elastic manner and on the liquid matrix in a viscous manner. Following a micro‐mechanics approach, an analytical model has been derived for the nonlinear elastic compression of two‐dimensional, orthotropic, plain woven fiber cloths, containing two empirical constants. The model is validated by experimental data and the empirical constants determined in the compression of a wet, plain woven, glass fiber reinforcement. The effects of the compression of woven cloths during processing are demonstrated by the change of their permeability.