Instron 4400 Series Operator's Manual page 264

Glossary M10-94400-1
Yield Point.
Stress at which strain increases without accompanying
increase in stress. Only a few materials (notably steel)
have a yield point, and generally only under tension load-
ing.
Yield Point Elongation.
Strain at yield point of a material. It is an indication of
ductility.
Yield Strength.
Indication of maximum stress that can be developed in a
material without causing plastic deformation. It is the
stress at which a material exhibits a specified permanent
deformation and is a practical approximation of elastic
limit. Offset yield strength is determined from a stress-
strain diagram. It is the stress corresponding to the inter-
section of the stress-strain curve, and a line parallel to its
straight line portion offset by a specified strain. Offset
for metals is usually specified as 0.2%, i.e., the intersec-
tion of the offset line and the 0-stress axis is at 0.2%
strain. Offset for plastics is usually 2%.
Yield Strength Elongation.
Strain corresponding to yield strength of material. It is
an indication of ductility.
Yield Value.
Stress in an adhesive joint at which a marked increase in
deformation occurs without an increase in load.
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