Refine
Year of publication
- 2012 (1) (remove)
Document Type
- Doctoral Thesis (1)
Language
- English (1) (remove)
Has Fulltext
- yes (1)
Faculty / Organisational entity
Unidirectional (UD) composites are the most competitive materials for the production
of high-end structures. Their field of application spreads from the aerospace up to
automotive and general industry sector. Typical examples of components made of
unidirectional reinforced composite materials are rocket motor cases, drive shafts or
pressure vessels for hydrogen storage. The filament winding technology, the pultrusion
process and the tape placement are processes suitable for the manufacturing
using UD semi-finished products. The demand for parts made of UD composites is
constantly increasing over the last years. A key feature for the success of this technology
is the improvement of the manufacturing procedure.
Impregnation is one of the most important steps in the manufacturing process. During
this step the dry continuous fibers are combined with the liquid matrix in order to create
a fully impregnated semi-finished product. The properties of the impregnated roving
have a major effect on the laminate quality, and the efficient processing of the
liquid matrix has a big influence on the manufacturing costs.
The present work is related to the development of a new method for the impregnation
of carbon fiber rovings with thermoset resin. The developed impregnation unit consists
of a sinusoidal cavity without any moving parts. The unit in combination with an
automated resin mixing-dosing system allows complete wet-out of the fibers, precise
calibration of the resin fraction, and stable processing conditions.
The thesis focuses on the modeling of the impregnation process. Mathematical expressions
for the fiber compaction, the gradual increase of the roving tension, the
static pressure, the capillarity inside the filaments of the roving, and the fiber permeation
are presented, discussed, and experimentally verified. These expressions were
implemented in a modeling algorithm. The model takes into account all the relevant
material and process parameters. An experimental set-up based on the filament
winding process was used for the validation of the model. Trials under different conditions
have been performed. The results proved that the model can accurately simulate
the impregnation process. The good impregnation degree of the wound samples
confirmed the efficiency of the developed impregnation unit. A techno economical
analysis has proved that the developed system will result to the reduction of the
manufacturing costs and to the increase of the productivity.