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Tensile
Tensile
properties are the most important single indication of strength
in a material. The force necessary to pull the specimen
apart is determined, along with how much the material stretches
before breaking.
The
elastic modulus ("modulus of elasticity" or "tensile modulus")
is the ratio of stress to strain below the proportional
limit of the material. It is the most useful tensile data
because parts should be designed to accommodate stresses
to a degree well below this.
For
some applications where almost rubbery elasticity is desirable,
a high ultimate elongation may be an asset. For rigid parts,
on the other hand, there is little benefit in the fact that
they can be stretched extremely long.
There
is great benefit in moderate elongation, however, since
this quality permits absorbing rapid impact and shock. Thus
the total area under a stress-strain curve is indicative
of overall toughness. A material of very high tensile strength
and little elongation would tend to be brittle in service.
ASTM D-638.
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