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Young's Modulus / Force per Area Ques.

  1. Oct 5, 2009 #1
    Hello,

    My question in this. If you have a system where two rods (different moduli of elasticity and different cross sectional areas, but equal in length) are compressed uniformally by a load, how do you calculate the compressive deformation in the rods. The compression of both will be identical, and I understand how to calculate the compression if only one of the two rods was present. But how does having another rod with a different elastic modulus and cross sectional area affect the system. I understand that the compression in the two rod system should be less than the compression of just the single rod system. Thanks!
     
    Last edited: Oct 5, 2009
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  3. Oct 5, 2009 #2

    Mapes

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    Hi vhariharan, welcome to PF. It would be a good idea to write the equation connecting stress and strain for each beam. What can you say about the strains? Can you relate the stresses (in conjunction with the cross-sectional areas) to the total external load?
     
  4. Oct 5, 2009 #3
    I have the equations relating stress, strain, and the modulus of elasticity, and I understand that the strain in each rod is equal. But how would you relate the stress in each rod to the total external load?
     
  5. Oct 5, 2009 #4

    Mapes

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    What's the relationship between stress and force?
     
  6. Oct 5, 2009 #5
    force=stress*cross sectional area, but how do you relate the stress in each of the rods to the total force applied? Is it just the sum of the stress*cross sectional area of both rods? But then we have two unknowns again (the stress in each of the rods)
     
  7. Oct 5, 2009 #6
    Got it....Thanks!
     
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