Abstract
Composites consist of two or more phases that are usually processed separately and then bonded, resulting in
properties that are different from those of either of the component materials. Polymer matrix composites
generally combine high-strength, high-stiffness fibers (graphite, kevlar, etc.) with low-density matrix materials
(epoxy, polyvinyl, etc.) to produce strong & stiff materials that are lightweight. Laminates are generally built up
from multiple layers of lamina; the fibers within each lamina are generally parallel, but laminates usually contain
lamina with their fibers oriented in various directions. Each lamina is an anisotropic layer with properties varying
as a function of fiber angle. Loading along the fibers (longitudinal) is modeled as Isostrain while loading
perpendicular to the fibers (transverse) is modeled as Isostress; these two directions generally represent the
extremes in material behavior. Fiber and matrix material property data can be used to predict/approximate the
properties of laminated composites using the Rule of Mixtures. In this investigation, the elastic modulus of
composites loaded at various angles with respect to the fiber direction will be predicted, tested and discussed.
The burn-off method will be applied to determine the fiber volume of the composites being investigated, and
ultimate strength and elastic modulus results will be compared with those of metals and polymers.
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