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Calculating resultant stress

  1. Jun 14, 2014 #1
    1. The problem statement, all variables and given/known data

    "see attachment"

    Normally I would assume that the stress caused by the point load at A is equal to σ=P/Area. however since there is a distance between the two points and because of Saint Venants principle, I don't think that the stress at A will be the same with the stress at D. In order to find the stress at D, do I have to find the centroid or the moment? (using this equation σ=((-My)/I) ) or angle of twist??

    Attached Files:

  2. jcsd
  3. Jun 14, 2014 #2


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    Well, the attachment is not totally clear on the position of A, but let's assume that the force at A is applied at the center of the cross-section.

    Why would you assume that a centrally loaded member has developed a bending moment?

    What is it about this problem which makes you think St. Venant's principle applies?

    You've got a prismatic member with a square cross-section. Can't you identify the location of the centroid without calculation?
  4. Jun 14, 2014 #3
    I don't think that there will be any moment in the center load. (Can I assume that the stress will be exactly the same for the entire rectangle?)

    For the St. Venants principle, I think it is there because point D is on the side of the rectangle, i doubt that it will experience the same stress as that of the centre of the rectangle.

    The centroid should be in the centre of the rectangle.
  5. Jun 14, 2014 #4


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    Well, axial loads are assumed to produce the same stress over the entire cross-section. After all, that's what σ = P/A means.
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