Effect of the Fibre Orientation Distribution on the Mechanical and Preforming Behaviour of Nonwoven Preform Made of Recycled Carbon Fibres

Recycling carbon-fibre-reinforced plastic (CFRP) and recovering high-cost carbon fibre (CF) is a preoccupation of scientific and industrial committees due to the environmental and economic concerns. A commercialised nonwoven mat, made of recycled carbon fibre and manufactured using carding and needle-punching technology, can promote second-life opportunities for carbon fibre. This paper aims to evaluate the mechanical and preforming behaviour of this nonwoven material. We focus on the influence that the fibre orientation distribution in the nonwoven material has on its mechanical and preforming behaviour at the preform scale, as well as the tensile properties at composite scale. The anisotropy index induced by fibre orientation is evaluated by analysing SEM micrographs using the fast Fourier transform (FFT) method. Then, the anisotropy in the tensile, bending, and preforming behaviour of the preform is inspected, as well as in the tensile behaviour of the composite. Additionally, we evaluate the impact of the stacking order of multi-layers of the nonwoven material, associated with its preferred fibre orientation (nonwoven anisotropy), on its compaction behaviour. The nonwoven anisotropy, in terms of fibre orientation, induces a strong effect on the preform mechanical and preforming behaviour, as well as the tensile behaviour of the composite. The tensile behaviour of the nonwoven material is governed by the inter-fibre cohesion, which depends on the fibre orientation. The low inter-fibre cohesion, which characterises this nonwoven material, leads to poor resistance to tearing. This type of defect rapidly occurs during preforming, even at too-low membrane tension. Otherwise, the increase in nonwoven layer numbers leads to a decrease in the impact of the nonwoven anisotropy behaviour under compaction load.

Modelling the permeability of random discontinuous carbon fibre preforms

A force-directed algorithm was developed to create representative geometrical models of fibre distributions in directed carbon fibre preforms. Local permeability values were calculated for the preform models depending on the local fibre orientation, distribution and volume fraction. The effect of binder content was incorporated by adjusting the principal permeability values of the meso-scale discontinuous fibre bundles, using corresponding experimental data obtained for unidirectional non-crimp fabrics. The model provides an upper boundary for the permeability of directed carbon fibre preform architectures, where predictions are within one standard deviation of the experimental mean for all architectures studied.

Efficient Characterization and Modelling of Material Behaviour of LFT for Component Simulations

Modeling failure and progressive damage of long fibre reinforced thermoplastics (LFT) presents a challenging task since local inhomogeneities, anisotropic fibre orientations, and strain-rate dependence must be taken into account also on the microscale. We show that for simple geometries, the material behaviour of the composite can be modelled using layered geometrical models. But for more complex geometries, this approach fails since the fibre orientation distribution is inhomogeneous. In this case, multiscale methods allow the accurate and efficient prediction of the material behaviour with the local fibre orientation taken from an injection molding simulation. This material model can be extended to viscoplasticity and integrated into the NTFA-TSO method from Michel & Suquet (2016). In this way, we can obtain an accurate and efficient multiscale method for the realistic modelling of LFT.

Fibre Orientation Distribution Assessment of Dynamically Sheet Formed Hemp Fibre Mats by Image Analysis

Orientation of fibre preforms is an important factor that affects the properties of short natural plant fibre composites. In this paper, oriented short hemp fibre mats were produced using dynamic sheet forming and the fibre orientation distribution in the mats was analysed using ImageJ software as well as by a simple program developed on a MATLAB software package. The OrientationJ plug-in of ImageJ gave an orientation distribution curve with a peak at a predominant direction of 0° supporting alignment during dynamic sheet forming and from MATLAB software, a mean ratio of 0.64 was obtained for the oriented mats compared to 0.74 for an aligned bundles.

Modelling of fibre orientation probability distribution in the jet-to-wire impingement

Fibre orientation distribution is essential factor affecting the properties of produced paper. The fibre orientation distribution is mainly determined by the fluid dynamics in the wet-end and in the wire-section of the paper machine. In this work the fibre orientation probability distribution in the paper machine jet-to-wire impingement is studied using modelling. The model used in this work is based on diffusion-convection equation. In addition to the transport of the fibres due to the mean flow, the model includes flow induced rotation of the fibres and randomising turbulence effects. Thus, the purpose of the model is to estimate the effect of the flow dynamics on the development of the fibre orientation probability distribution.