Civil Engineering Reference
In-Depth Information
Figure 1.
Loading assembly for tensile tests conducted at low temperatures.
The dashed line
(c)
in Fig. 2 corresponds to a typical stress (force)
versus strain (displacement) curve for a material which obeys Hooke's Law
(elastic) and curve
(b)
represents a viscoelastic behavior. It can be observed
from the figure that the curve from the thermoplastic material is almost
linear for a force (stress) below 300 N. In the linear region of the curve, the
material behaves like an elastic material and obeys Hooke's Law. The curve
in Fig. 2 can be represented by the following equation:
[6]
Eq. (3)
σ
=
E
ε
where
is strain, and
E
is the slope of the curve (resistance
to tensile forces).
E
is also called Young's modulus of the material. It can
be seen from Eq. 3 that the higher the
E
value, the higher resistance of the
material to tensile forces.
σ
is the stress,
ε
