Shear Stress of a particular length rod

  1. Just a quick question:

    Wikipedia tells me that due the shearing stress, the yeild strength of Stainless Steel is 520Mpa

    But how can i find out the Yeild strength of a 100mm long rod with diameter 10mm.

    Is the info for wikipedia based on a 1mx1mx1m cube? or some sort of SI unit.

    Cheers
     
    Last edited: May 8, 2008
  2. jcsd
  3. mgb_phys

    mgb_phys 8,952
    Science Advisor
    Homework Helper

    The stress doesn't depend on the length of the rod - it only depend son the cross section area.
    Mpa is mega pascal - is a unit of pressure, 1 pa is one Newton/m^2
    So 1Mpa is around 100,000 Kg/m^2, or 145psi
     
  4. i see, but the what cross section area are the stresses relating to? and does it also depend on the shape?

    If i see the value of 520MPA in a book for s steel, how can i use that to aplly it to a rod with a given diameter?
     
  5. Andy Resnick

    Andy Resnick 5,851
    Science Advisor
    Education Advisor

    Calculating the deformation of a rod requires three things- the applied stress, the mechanical properties of the rod, and the geometry of the rod. All you have right now is (I'm guessing) the Young's modulus for a particular type of stainless steel and the geometry of the rod.

    Try surfing through these, see if it helps:

    http://www.clag.org.uk/beam-menu.html
    http://www.mhhe.com/engcs/engmech/beerjohnston/mom/lectureppt.mhtml
    http://www.grantadesign.com/resources/shapes/solutions/elastic.htm

    Note- thin beams have a simple approximate solution. Yours, with an aspect ratio of 10, may or may not be amenable to that approximation.
     
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