Unformatted text preview: ith positionthewire is
an to the bond curve represents the of the of energy between when the only
The
pulled or ions a die to reduce of diameter.
then experience a forces acting onor ions.throughare the atomic forces itsattraction and repulsion. If
the atoms
bondforce curve yp The strain at which application
other external forces or sources of energy act on the systemthat example, thedeformation
yield point strain The curve (for describes the
of external loads, an electromagnetic ﬁeld, or temperature changes), quantities such as
between The yield
becomes permanent. be total force between key issues in
well
combination of timebond length andrelationship energy may thealtered. Inpoint strain istwo atoms
effective bond
fact, one of the
or ions toin a able to understandsteel, which exhibit the two
asbemetals such as and model the interaction “sharp”
function of the distance between a between
deﬁned
t deformation. Such materials engineering is
atoms or ions. This curve plastic deformation. derivative
external
transition scale elastic
t prominently in polymers. variables and atomic fromstructures. to is equivalent to the
Consider the response bondenergy curve. external load. Figure 2.4–2a showed
of a system
an
of the stress of atoms tostress at which deformation
a combination of spring bondforce curve is approximatelyThe near the equilibrium position. The slope
yield
ys
that the
linear
The in a tensile to displace atoms from their
of the curve, Fbond length
x , at x0 is permanentequilibrium separation distance
becomes a measure of the force requiredtest.
equilibrium positions. Mathematically, near x 0ions. It can be estimated fromto
the displacement x i proportional
between two atoms orThe elastic propertys of solids that
constant between shear
Young’s modulus
the force:
either the the inherent stiffness of the material.theis also
ich is a measure of the
describes bondenergy curve (the point where It energy
F
minimum)aor the bondforce curve (the point where
F
xis a or
E
aterial.
the slope of the stressstrain curve in the elastic (2.5–1)
region.
x
the total force is zero).
whic...
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 Spring '10
 sowell
 Physics, Atom, The Crucible, ........., IRWIN / Schaffer

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