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Materials:
Composites
Introduction
to Composites
Composites are materials
formed from a mixture of two or more components
to produce a material with properties or
characteristics superior to those of the
individual materials.
Most composites are formed
of two phases: Matrix and Reinforcement.
The matrix is a continuous phase material
which is usually less stiff and weaker than
the reinforcement. It is used to hold the
reinforcement together and distribute the
load among the reinforcements. Reinforcements
in the form of fibers, fabric, whiskers,
or particulates are embedded in the matrix
to produce the composite. They are discontinuous,
usually stronger and stiffer than the matrix
and provide the primary load-carrying capability
of the composite.
The shape of the finished
part is dependent on a mold, die or other
tooling that controls the geometry of the
composite during processing. Composites
may be thought of as advanced materials,
but they mimic the features of living organisms
that have existed for millions of years
such as the microstructures of wood and
bioceramics like mollusk shells.
The fibers and matrix of
advanced composites may be combined using
a variety of fabrication processes, with
the choice depending on the desired alignment
of fibers, the number of parts to be produced,
the size and complexity of the parts, and
so on. Perhaps best known for their use
in aerospace applications, advanced composites
are also used by the automotive, biomedical,
and sporting goods markets.
All of these developments
mean a larger and more complicated materials-choice
menu. This diversity has made plastics applicable
to a broad range of consumer, industrial,
automotive, and aerospace products. It has
also made the job of selecting the best
materials from such a huge array of candidates
quite challenging.
Composites
fall into the general categories:
- Polymer-Matrix Composites
- Thermoplastic
Composites
- Thermoset Composites
- Laminated Plastics
- Ceramic-matrix Composites
- Metal-matrix Composites
For a discussion of composite
manufacturing methods--
See Also--Composite
Forming Processes
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