Particle deposition mechanisms during processing of advanced composite materials

Plastics, Rubber and Composites

2011

The motion of particles through a system of permeable fibre bundles is considered. The system is discretisised with Voronoi diagrams and the dissipation rate of energy is minimised with respect to the stream function in a system with periodic boundary conditions. The flow of the particles is in the transversal direction to the fibre bundles and the particles are hindered to move out of the plane allowing for two-dimensional calculations. The motion of particles is assumed to be slow with respect to the flowrate so that particles are driven by the Stokesian force for stationary particles. In this case, the flow distribution is essentially dependent on the particle configuration and strictly follows the motion of particles. When testing different sizes of the particles, it is shown that there is a qualitative agreement between model and experiments previously performed. In particular, stationary flow leads to particle depositions in front of the fibre bundles and small particles move into the fibre bundles while large ones are stuck at the border.

“…This result is in qualitative agreement with those in Ref. 7 where it is observed that small particles move into the fibre bundles while the large ones are stuck at the border.…”

Section: Resultssupporting

confidence: 93%

Modelling of particle deposition during impregnation of dual scale fabrics

Frishfelds

Plastics, Rubber and Composites

2011

“…18 This is not an unlikely assumption although the exact mechanisms for deposition are still to be sorted out. [14][15][16] Deposition efficiency in turn is defined as the ratio of the number of fibres that are deposited within a given time to the number of fibres that are simulated.…”

Section: Simulation Conditionsmentioning

confidence: 99%

“…This may take place both at the wetting flow front and in the saturated flow. [14][15][16] Little is known, however, of the detailed motion of nanosized fibrous particles in composites manufacturing in general, and of their motion within and between fibre bundles specifically. A central feature of the nanofibres is that they may experience both Brownian translational and rotational motion, the intensity of which is dependent on particle characteristics, flow pattern and channel geometry.…”

Section: Introductionmentioning

confidence: 99%

Motion of dispersed carbon nanotubes during impregnation of fabrics

Högberg

Plastics, Rubber and Composites

2011

Interest is growing in the development of hierarchical composites, in which nanoscale particles are used alongside the traditional microscale reinforcing fibres. To produce high quality multiscale materials, knowledge of mechanisms governing nanofibre distribution and orientation is crucial. In this work, analysis and numerical simulations are used to model the motion of dispersed carbon nanotubes during impregnation of dual scale fabrics in composites manufacturing. Results suggest that nanofibre displacement and orientation is mainly deterministic on mesoscale, while typically random on microscale. The randomising Brownian torque may still influence the motion and trigger the fibre to make 180u rotations in the former, however, when acting together with the fluid shear. Fibre deposition may lead to a total blockage of the flow within the microchannels, whereas only minor deposition is expected in the mesochannels.

“…11,31 This may lead to an extensive filtration at the border of the fibre bundles. 21 Filtration may also take place in the bulk where most fibres are wetted. 21 In both cases, particle size relative to the spacing inside the fibre bundles is an important factor deciding the particle routes and whether the particles are going to be trapped or not.…”

Section: Introductionmentioning

confidence: 99%

“…When testing different sizes of the particles, it is shown that there is a qualitative agreement between model and experiments previously performed. 21 Another modelling approach was taken in Reference [42,43] where a Stoke-Brinkman technique has been developed to solve this problem including a meso-scale flow simulation method that accounts for the interfacial stress jump. The technique was extended to display the coupled flow in dual-scale porous media.…”

Section: Introductionmentioning

confidence: 99%

Modeling filtration of particulate flow during impregnation of dual-scale fabrics

Journal of Composite Materials

Frishfelds

2012

Filtration of particles during impregnation of dual-scale fabrics is studied numerically for a number of geometries and initial positions of the particles by improving a previously derived model for a high density of the particles. The initial position and size of the particles are varied. The main result is that structural composites can be tailor-made as to additional properties by such an approach.