Abstract
A hydrodynamic alignment process has been developed for converting discontinuous random carbon fibers into tapes with a highly aligned orientation distribution to greatly improve the applicability of recovered fibers to composite parts. In hydrodynamic alignment processes short fibers are aligned by the velocity gradient along the flow direction in a convergent nozzle. Thereafter the jet of fiber suspension is deposited on a nylon mesh and the now redundant dispersion medium is drained away to leave an aligned fiber tape. The fundamental physical principles at work in the process have not been widely studied and are shown in the present work to greatly influence the properties of the resulting materials. In this work, the influence of suspension jet stability on the fiber orientation distribution was examined and the liquid jet break-up regime was determined. To explore the factors which can affect the suspension jet stability, different nozzle geometries, viscosities of dispersion media, fiber lengths and Reynolds numbers were applied in experimental work. The shear rate profiles inside different nozzles were simulated by Computational Fluid Dynamics methods and the results described in this paper.
| Original language | English |
|---|---|
| Article number | 103102 |
| Number of pages | 12 |
| Journal | International Journal of Multiphase Flow |
| Volume | 120 |
| Early online date | 29 Aug 2019 |
| DOIs | |
| Publication status | Published - 30 Nov 2019 |
Funding
The authors gratefully acknowledge the support of the Boeing Company under the Boeing / University of Nottingham strategic collaboration in carbon fiber recycling.
Keywords
- fiber alignment
- jet break-up regimes
- shear flow
- short fiber suspension