Stress-Strain Curve

Discussion in 'Homework Help' started by Hello, Jan 6, 2009.

  1. Hello

    Thread Starter Active Member

    Dec 18, 2008
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    Can you please have a look at the attached file. I have answered the questions but not sure if they are all right!


    Any help is greatly appreciated
     
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Yes the curve shows ductile behaviour.

    Deformation occurs at any point of the curve, not just at A.

    Point A marks the beginning of permanent set or plasticity. It is called the Elastic Limit or the Limit of Proportionality.

    Point B marks the Yield Point.

    Beyond Y the stress decreases with increasing strain and necking occurs. The stress at Y is the ultimate tensile strength.
    X is the final fracture point.

    The slope of the curve is the modulus of elasticity. (Youngs Modulus).

    If the material is stressed beyon the elastic limit at A to point B and then destressed, the material will be work hardened (strain hardened) so that B is now the elstic limit and the new loading curve will follow the right hand dashed line. It will also have acquired a permanent set equal to the difference between the two dashed lines along the strain axis.
     
    Last edited: Jan 7, 2009
  3. Hello

    Thread Starter Active Member

    Dec 18, 2008
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    I thought point B was the 'yield strength' as it causes a permanent strain of 0.002.
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
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    513
    Any point between A and Y is a 'Yield Point' It just depends where you get to.

    0.002 strain is an arbitrary figure.

    Read also my last paragraph of post #2 again.
     
  5. Hello

    Thread Starter Active Member

    Dec 18, 2008
    82
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    Thanks again.
     
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