Comput.Meth.Appl.Mech.Engng. 185, 191-201, 2000


ON FIBER CURVATURE EFFECTS IN THE ANALYSIS
OF UNIDIRECTIONALLY REINFORCED
COMPOSITE STRUCTURES

C.M. Chimani, F.G. Rammerstorfer and H.J. Böhm

Institute of Lightweight Structures and Aerospace Engineering,
TU Wien, Vienna, Austria


Abstract - 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.

(hjb,000720)