The ratio of normal stress to the corresponding strain for
tensile or compressive stresses less than the proportional limit of the
In tensile testing,
yield point is the first point on the stress-strain curve at which an increase
in strain occurs without an increase in stress.
The load in pounds per square inch where the material under test begins to
change dimensions and will not completely recover when the load is removed.
Yield strength will normally be lower than ultimate strength. Generally
speaking, the more rigid a material is, the closer will be yield and ultimate
strengths. Furthermore, the more resilient a material is, the greater the
spread between yield and ultimate strengths.