Local anisotropy analysis of injection moulded fibre reinforced polymer composites

Abstract

The fibre orientation distribution in a material sample extracted from an injection moulded plate, displaying the commonly encountered layered shell–core–shell structure, was analyzed. Starting from a micro-tomography reconstruction of the sample, instead of trying to isolate each single fibre and measuring its geometrical properties, we derived the components of a fabric tensor from the evaluation of a global anisotropy parameter, the mean intercept length MIL. This parameter, commonly employed for the analysis of biological and geological structures, proved to be an efficient tool for the analysis of the structure of short fibre reinforced composites. The local variations of the degree of anisotropy (ratio of the maximum and minimum eigenvalues of the fabric tensor) from the shell to the core layers of the injection moulded plate could be captured and information about the local average fibre orientation angle was also obtained

Phase contrast micro-tomography and morphological analysis of a short carbon fibre reinforced polyamide

“…On the contrary, in short fibre reinforced composites fibres are dispersed along all directions even when preferred orientations are present, so that the 3D MIL locus can be approximated by an ellipsoid [7,11,12] and a compact tensor notation can be used to define fibre arrangement properties. In the second order MIL fabric tensor thus defined, eigenvectors correspond to the principal directions of the anisotropic structure, while the normalized eigenvalues H i can be considered a measure 10 of fibre distribution along these directions.…”

“…Instead, a global approach was applied using the Mean Intercept Length (MIL), as recently introduced by some of the Authors for short glass fibre reinforced polyamide [7].…”

“…Characterization of anisotropy by MIL, commonly utilized in biomechanics and geology, was adopted for SFRP samples. In this way, it was possible to identify local preferred fibre directions and anisotropy degrees in glass fibre reinforced thermoplastic polymers [7,11,12].…”

“…A review of the usual methods is discussed in [7]. The most common destructive method consists in the analysis of the elliptic traces in several sections of the sample, from which the orientation of each single fibre can be inferred [8,9].…”

Influence of Hygrothermal Aging on Poisson’s Ratio of Thin Injection-Molded Short Glass Fiber-Reinforced PA6

“…The glass fiber orientation is generated mainly by the injection molding process and can be determined visually or by X-ray diffraction analysis [4,5]. The glass fiber orientations can be represented by the tensor second stage T FOD as shown in Equation (1) based on the angles Φ and Θ (from polar coordinate system, see Figure 1), which describes the average glass fiber orientation in a defined region in the Cartesian coordinate system according to Advani and Tucker as well as Bay and Tucker [6][7][8].…”