Civil Engineering Reference
In-Depth Information
is measured as a function of time or temperature. The plot of expansion (or
contraction) versus temperature (or time) can then be used to obtain
T
g
, the
coefficient of thermal expansion (CTE), softening temperature, and Young's
modulus.
Figure 7.
TMA measurement principle.
(Reprinted with permission from Seiko TMA
Manual.)
The change in linear dimension as a function of temperature can be
described by the following:
T
2
=+
∫
Eq. (14)
LL
1
1
(
α
T
)
2
l
T
1
α
l
is the coefficient of linear expansion, and
L
1
and
L
2
are the lengths
of the specimen at temperatures (or time)
T
1
and
T
2
respectively. If the
difference between
T
2
and
T
1
is relatively small, then the equation can be
represented by:
where
Eq. (15)
L
2
-
L
1
=
L
1
α
1
(
T
2
-
T
1
)
or it can be rewritten as:
1
∆
∆
L
T
α
l
=
Eq. (16)
L
1
