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Unformatted text preview: s the ability of a material to resist, or oppose, the
scientists and engineers have spent a good part of their time predicting material propere eutectoid transformation
transport of electrical charge in response to an external
ties. This section presents some elementary approaches for estimating properties of
electric ﬁeld.
composite materials. For simplicity, we limit our discussion to properties of unidirectional
ﬁber –reinforced composites.
The ﬁrst ferrite that forms when Important factors in any A process in which the thickness of a volume
a
rolling model for predicting composite properties are the ﬂat plate
quenched through the austenite fraction of ﬁbers reduced by compressing it betweenthe ﬁber diameter (d).
and
is Vf , the volume fraction of the matrix Vm , and two cylindrical
and held at a temperature below
rolls.
14.5.1 Estimation of Fiber Diameter, Volume Fraction, and
mation temperature.
rubber A noncrystalline or amorphous ﬂuidlike
Density of the Composite
ess in which resinimpregnated
material that is above its glass transition temperature at
In an ideal twocomponent composite, the ﬁber and matrix volume fractions are related
ugh heated dies to make long
the
by the equation: temperature of interest, usually room temperature.
mposite products such as Ibeams.
Only
Vf Vm 1 polymers can be rubbers.
(14.5–1)
s for making carbon and ceramic equation assumes nomixturesa unidirectional composite the ﬁber volume fraction
rule of porosity. In
A formula that expresses the
This
is equal to thecomposite occupied by ﬁbers a linear sum plane. Figure 14.5–1
area fraction properties as in the transverse of the constituent
mer precursor ﬁber containing the
shows a picture of a transverse plane obtained by sectioning a small sample of a coms heated to temperatures high
properties weighted with a simple image analysis respective
posite. Vf can be determined by using a PC in proportion to theirprogram such as
ical changes resulting in the desired Photoworkshop. Notice in Figure 14.5–1 that the ﬁber diameter and spacing vary
Adobe
volume fractions.
signiﬁcantly as a result of the manufacturing process.
The densitysacriﬁcial anode be determined by a cathodic of mixtures as
of the composite, c , can A version of simple rule protection
One of four values, three of which
follows:
involving the intentional formation of a galvanic cell by
1⁄2, that together determine
ther is
Vf f Vm another, more anodic metal in electrical contact
(14.5–2)
placing m
c
other important characteristics of
where f is the with the metalis the matrix density. The rule of mixtures can be used
ﬁber density and m to be protected.
to calculate any composite property that does not depend on the spatial relationship of its
atom.
Schmid’s law The equation that relates the orientation
components.
interaction between an electron and
of a crystal and the normal stress to the shear stress at
the loss of both charge carriers. 14.5.2 Estimation of Elastic Modulus and Strength
which plastic deformation occurs.
ction of some of the stored energy this section, we derive simple relationships for estimating theanion vacancy
In
Schottky defect Small cation and elastic modulus and
strength of uni...
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This note was uploaded on 02/25/2013 for the course PHYS 2202 taught by Professor Sowell during the Spring '10 term at Georgia Tech.
 Spring '10
 sowell
 Physics, The Crucible, ........., Tensile strength, IRWIN / Schaffer

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