Comput.Meth.Appl.Mech.Engng. 185, 191-201, 2000
ON FIBER CURVATURE EFFECTS IN THE ANALYSIS
OF UNIDIRECTIONALLY REINFORCED
C.M. Chimani, F.G. Rammerstorfer and H.J. Böhm
Institute of Lightweight Structures and Aerospace
This paper studies the question whether or not neglecting fiber curvature
effects in mean field methods - in particular the Mori-Tanaka method -
used for describing the material laws of matrix-fiber composites leads
to significantly erroneous results, when they are used in the analysis
of axisymmetrical composite structures or structures reinforced by
curved aligned continuous fibers.
For comparison an exact analytical solution for a layered cylinder under
thermo-mechanical loading is derived, which can serve as a model for
circumferentially reinforced cylindrical composite structures.
For obtaining further comparative results classical lamination theory
and a computational hexagonal cell tiling concept are employed.
It is shown that in most cases the micromechanical effects resulting
from the curvature of the fibers are negligible as far as the global,
i.e. structural, thermo-mechanical behavior is concerned.
Accordingly, the use of micromechanical methods based on the Mori-Tanaka
approach appears to be justified for composites with curved aligned
reinforcements provided the radius of curvature is very large in
comparison with the fiber diameter, an assumption which is fulfilled in
nearly all cases.