3D geometric modelling of discontinuous fibre composites using a force-directed algorithm

Abstract

A geometrical modelling scheme is presented to produce representative architectures for discontinuous fibre composites, enabling downstream modelling of mechanical properties. The model generates realistic random fibre architectures containing high filament count bundles (>3k) and high (~50%) fibre volume fractions. Fibre bundles are modelled as thin shells using a multi-dimension modelling strategy, in which fibre bundles are distributed and compacted to simulate pressure being applied from a matched mould tool. FE simulations are performed to benchmark the in-plane mechanical properties obtained from the numerical model against experimental data, with a detailed study presented to evaluate the tensile properties at various fibre volume fractions and specimen thicknesses. Tensile modulus predictions are in close agreement (less than 5% error) with experimental data at volume fractions below 45%.Ultimate tensile strength predictions are within 4.2% of the experimental data at volume fractions between 40%-55%. This is a significant improvement over existing 2D modelling approaches, as the current model offers increased levels of fidelity, capturing dominant failure mechanisms and the influence of out-of-plane fibres.

Modelling the permeability of random discontinuous carbon fibre preforms

“…The 3D geometry representation of a DCFP preform was produced by an algorithm developed by Harper et al [21]. A typical output from the model is shown in Figure 7.…”

“…Fibre bundles were continuously deposited over the region of interest until the target fibre volume fraction was achieved. A force-directed approach using an attraction-repulsion mechanism was used to prevent bundle intersections and to define the through-thickness distribution of fibre bundles [21]. When the fibre architecture generation is complete, each deposited fibre bundle is represented by a separate surface mesh.…”

“…This paper presents a novel approach for local permeability calculation, using an alternative geometrical modelling scheme to produce more representative discontinuous fibre architectures. A force-directed algorithm is adopted to simulate the through-thickness consolidation of the deposited fibre bundles during preforming, in order to achieve realistic local fibre distributions [21]. The effect of preform binder content is taken into account in the calculation of local permeability values, which are used as input for resin injection simulations.…”

Development and assessment of modelling strategies to predict failure in tow-based discontinuous composites

“…Selezneva et al [27] In addition to the analytical models described above, numerical models for TBDCs have also been developed [28,29]. These models consider either an explicit representation of the fibres/tows [29], or a discrete grid of equivalent laminates with stochastic layups [28], and use Finite Element (FE) simulations of RVEs to cope with the variability in microstructures and the complexity of stress fields.…”

“…• The model allows a significant reduction in computational cost compared to conventional FE simulations of RVEs (which can take four hours of CPU time to complete the analysis of a single loading case [29]). In comparison, our model requires approximately 300 seconds to predict the full failure envelope (as shown in Figure 13a) of a TBDC material, using the FPF macroscale criterion (which was validated against the PDM) and thee numerical parameters shown in Table 3.…”