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Yield Point
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Can be defined as the point where a tensile test piece begins to
extend permanently. If the load is reduced to zero, the test piece
will not return to its original length. |
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Yield Strength
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The stress at which general plastic elongation of the test piece
takes place. This point is well defined in hardened and tempered or
annealed structures but can be ill defined in "as drawn" structures.
It is the stress at which a material exhibits a specified deviation
from proportionality of stress and strain. An offset of 0.2% is used
for many metals. Compare with tensile strength. |
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Young's Modulus
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A
measure of rigidity based on the ratio of stress to corresponding
strain in an elastic material. Within the limits of elasticity, the
ratio of the linear stress to the linear strain is termed the
modulus of elasticity or Young’s Modulus and may be written as E
=(Stress/Strain). It is this property that determines how much a bar
will sag under its own weight or under a loading when used as a beam
within its limit of proportionality. For steel, Young’s Modulus is
of the order of 205000 N/mm2. |
