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Stress and Strain Problem

  1. Feb 1, 2015 #1
    1. The problem statement, all variables and given/known data
    A 2.75 KN tensile load is applied to at test coupon made from 1.6 mm flat steel plate (E=200 GPa, v=0.30). Determine the resulting change in the 50 mm gage length. 5d38ae064dd27f4e290811bc0416e896.jpg

    2. Relevant equations
    εx = (σx/E) + (-Vσy/E) - (Vσz/E)
    εy = (-vσx/E) + (σy/E) - (Vσz/E)
    εz = (-vσx/E) - (Vσy/E) + (σz/E)

    3. The attempt at a solution
    (a) Area = (0.05)(0.0016) = 0.00008 m2
    σx = P/A = (2.75*103) / 0.00008
    σx = 34.4*106 Pa

    εx = (34.4*106) / (200*109)
    εx = 1.719*10-4

    Δab = εx(ab) = (1.719*10-4 / 0.05
    Δab = 8.595*10-6

    The answer should be 0.0358 mm. What am I doing wrong?
     
  2. jcsd
  3. Feb 2, 2015 #2
    For one thing, your cross sectional area is 1.6x12, not 1.6x50. Also, you should be multiplying by 50 in getting Δab, not 0.05.

    Chet
     
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