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Homework Help: Plastic deformation

  1. Apr 26, 2010 #1
    1. The problem statement, all variables and given/known data
    the graph below shows the behaviour of a sample of a metal when it is stretched until it starts to undergo plastic deformation.

    image201004270001.jpg

    what is the total work done in stretching the sample from zero extension to 12.0mm?
    simplify calculation by treating the region xy as a straight line
    2. Relevant equations



    3. The attempt at a solution
    i have used the formula total work done = area under the graph f-e
    550x12x10^-3x0.5=3.3
    which im wrong.
    wouldnt figure out the problem
    the ans is 3.55J
     
  2. jcsd
  3. Apr 26, 2010 #2

    Mapes

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    The problem says to assume x-y is a straight line, not to assume O-y (where O is the origin) is a straight line. Know what I mean?
     
  4. Apr 27, 2010 #3
    so the area x-y is a trapezium?
    using rule of trapezium
    0.5x(500+550)x2.0x10^-3
    =1.05
    plus the area before deformation
    500x10x10^-3x0.5=2.5
    2.5+1.05=3.55
    yeah i got the answer thx
     
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