Instron 4400 Series Operator's Manual page 255

Glossary
Strain Energy.
Measure of energy absorption characteristics of a mate-
rial under load up to fracture. It is equal to the area un-
der the stress-strain curve, and is a measure of the
toughness of a material.
Strain Hardening Exponent.
Measure of increase in hardness and strength caused by
plastic deformation. It is related to true stress and true
strain by the equation:
η
σ = σ δ
0
where σ is true stress, σ is true stress at unit strain, δ is
0
true strain and η is strain hardening exponent.
Strain Point.
Temperature at which internal stress in glass is substan-
tially relieved in about 1 hour. (ASTM C-336).
Strain Rate.
Time rate of elongation.
Strain Relaxation.
Alternate term for creep of rubber.
Strength Reduction Ratio.
Alternate term for fatigue notch factor.
Stress.
Load on a specimen divided by the area through which it
acts. As used with most mechanical tests, stress is based
B-29