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yield
Evidence of plastic deformation in structural
materials. Also called plastic flow or creep. See also flow.
yield
point
The first stress in a material, usually less than the
maximum attainable stress, at which an increase in strain occurs without an
increase in stress. Only certain metals - those that exhibit a localized,
heterogeneous type of transition from elastic deformation to plastic
deformation - produce a yield point. If there is a decrease in stress
after yielding, a distinction may be made between upper and lower yield
points. The load at which a sudden drop in the flow curve occurs is called
the upper yield point. The constant load shown on the flow curve is the
lower yield point.
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yield
strength
The stress at which a material exhibits a specified
deviation from proportionality of stress and strain. An onset of 0.2% is
used for many metals.
yield
stress
The stress level in a material at or above the yield
strength but below the ultimate strength, i.e., a stress in the
plastic range.
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