1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Torsion question

  1. Dec 15, 2009 #1
    Each of the two aluminum bars shown is subjected to a torque of magnitude . Knowing that , determine for each bar the maximum shearing stress and the angle of twist at B.

    Untitled.jpg

    Answers: a) 40.1Mpa 0.6630 degrees
    b) 50.9Mpa 0.9510 degrees

    my equations


    τmax=[tex]\frac{T}{alpha*h*b^2}[/tex]


    [tex]\frac{dΦ}{dx}[/tex]=[tex]\frac{T}{G*beta*hb^3}[/tex]


    so to find the angle of twist at B i can integrate [tex]\frac{T}{Gβhb^3}[/tex]dx from 0 to 0.3, but since the moment is constant throughout, the integral comes to [tex]\frac{T}{Gβhb^3}[/tex]*0.3

    and i get

    a) ΦB=[tex]\frac{1000}{26e9*0.14*0.06*0.06^3}[/tex]*0.3=0.0211979 rad = 1.21455degrees

    b) ΦB=[tex]\frac{1000}{26e9*0.245*0.095*0.038^3}[/tex]*0.3=0.03011 rad = 1.725degrees

    where the actual answers are much much smaller

    for the shear strength used the equation

    τmax=[tex]\frac{T}{alpha*h*b^2}[/tex]

    and i get

    a)τmax=[tex]\frac{1000}{0.21*0.06*0.06^2}[/tex]=22Mpa
    b)τmax=[tex]\frac{1000}{0.26*0.095*0.038^2}[/tex]=28Mpa

    a seemingly simple question but i have managed to get 0/4 correct answers, can anyone see where im going wrong?
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Similar Discussions: Torsion question
  1. Torsion misunderstanding (Replies: 19)

  2. How is this torsion? (Replies: 21)

  3. Torsion problem (Replies: 1)

Loading...