Recent Patents on In-Plane Permeability Measurement of LCM Composite Reinforcements

Abstract

Optimization of Liquid Composite Molding (LCM) processes using Darcy flow numerical simulation requires inputting accurate reinforcement permeability data. Historically introduced by its author to describe infiltration phenomenon, permeability coming from Darcy's law is usually used in LCM processes as a rheological parameter in order to predict the macroscopic resin motion during the filling stage. Resulting from the flow through a complex fibrous architecture, its measurement is very sensitive to the test conditions due to the high filaments flexibility and mesostructure heterogeneity. Reinforcements are currently anisotropic fibrous media and their in-plane permeability measurement requires specific facilities. Measurements can be performed in transient or steady state conditions, and in one-, two-or three-dimensional configurations. This paper describes the different existing experimental configurations, identification procedures and instrumentation techniques. Advantages and drawbacks of each method are discussed, in the particular case of 2D transient measurements, which are the most representative of Resin Transfer Molding process. Two recent patents using different instrumentation techniques are detailed. They are focused on the simultaneous identification of the in-plane principal permeability values in an anisotropic fibrous reinforcement. Some perspectives are suggested to improve the repeatability of such measurement results.

Resin infusion/liquid composite moulding (LCM) of advanced fibre-reinforced polymer (FRP)

“…Many different experimental apparatuses have been designed to measure permeability [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35], which can be characterised by the type of flow (radial or unidirectional), and whether measurement is made of in-plane or out-of-plane permeability. It is possible to further categorise measurements as those made for one value of V f or a series (discreet or continuous) of porosity, by the type of injection (constant flow rate or constant pressure), or by the type of fluid utilised (liquid or gas).…”

Effect of deformation on knitted glass preform in‐plane permeability

“…By integrating the Darcy's law under constant pressure loss in the fibrous media, the permeability can be calculated directly from the evolution of the flow front position with time. This method can be applied in 1D [29,30], 2D [23,31,32], or 3D [33,34] configurations, increasing the simultaneous measurement capabilities but also experimental and parameter identification complexity [35].…”

Efficient experimental characterisation of the permeability of fibrous textiles

“…6 Many different experimental techniques are presented in literature for the purposes of measuring the permeability behaviour of reinforcing materials. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] These experimental methods can be classified based on the following:…”