In short-fiber reinforced composites, it is widely accepted that the fiber orientation plays an important role on their overall physical and thermomechanical properties. To predict the properties of such composite materials, a full 3D fiber orientation characterization is required. A variety of destructive and nondestructive techniques have been developed, but all the methods have the same common point that they are very tedious and time consuming. Knowing that the fiber orientation induced by the flow remains mainly in the flow plane, an easier method has been performed for injection molded fiber-filled polymers. It is based on the simple 2D SEM image analysis of a specific 458-oblique section plane. Then, the indetermination of fiber orientation from an ellipse mark analysis does not exist anymore. This novelty also turns out to be much more accurate. To achieve measurements over large composite samples, the method has been fully automated.

The excellent processing properties of knitted preforms for composite applications, as formability and permeability, are not sufficient to compensate the poor mechanical characteristics of the resulting material. Initial preform deformation is a way to improve these properties, but it modifies the permeability and changes the optimal infiltration conditions. This article presents an experimental setup and discusses the reliability of the permeability measurements. Experimental results show that the course-wise permeability is significantly modified by the deformation of the fabric, whereas the wale-wise permeability is quite insensitive to the deformation. In an equivalent isotropic system, the deformation essentially influences the anisotropy ratio. This last route has been investigated by a few authors, showing that tensile and compressive properties of the composite are affected by initial preform deformation,

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.