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Homework Help: Simple framework, maximum force and stress.

  1. Aug 1, 2011 #1
    1. The problem statement, all variables and given/known data
    A simple framework by two rods linked in A, B and C. Burdened by a force F. The rods is of square cross section 30x30 mm and made by steel 1550-01 -> E = 210 GPa.

    [PLAIN]http://img718.imageshack.us/img718/125/ram001.jpg [Broken]

    Determinate maximum force F and the stress in the rods AB and BC.

    2. Relevant equations
    I = w*h^2/12

    Fb = pi^2*E*I/L^2

    3. The attempt at a solution
    My guess is that It's enough to calculate the breaking of BC to get the maximum force F.

    I = 0,03^4/12 = 6,75*10^-8 m^2

    Fb = 22,4 kN

    Then I assumed I could use tanX = a/b -> (a=F) -> F = 22,4*tan30 = 12,932 kN.

    Could that be the correct answer?

    For the stress I guess I should use σ=F/A, just by putting the things I got into that I get 22400/9*10^4 = 24,9 MPa, could that be the stress in BC? But then how do I get the stress in AB?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Aug 8, 2011 #2
    Anyone got an idea for this?
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