1. Not finding help here? Sign up for a free 30min 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!

Solid mechanics-how do i find the maximum momentum in this question?

  1. Nov 4, 2009 #1
    in this question, i am given the function for the xx stress as seen in the diagram below:
    http://lh6.ggpht.com/_H4Iz7SmBrbk/SvG3wUaPVAI/AAAAAAAAB6w/sMKXVGWomi8/Capture1.JPG [Broken]

    i am asked to sketch the stress distribution, which i have done
    http://lh3.ggpht.com/_H4Iz7SmBrbk/SvG3wPYlmdI/AAAAAAAAB6s/rd9T_ED6MK0/Capture.JPG [Broken]

    now i am asked to find the value of C which will give me the maximum value for Mo, which as far as i can see is Moment about the z axis.

    what ive done is

    Mz= -ʃʃ {(σxx)*y} dA

    now i know that there are 3 options,(3 functions for σxx) but i know that for y>=c and y<c the function for σxx is constant and -ʃʃ {y} dA is 0,(2nd area moment)

    therefore i think i must find it where -c<y<c,

    -ʃʃ {(-σy/c)*y} dA= σ/c * ʃʃ {(y^2} dA
    =σ/c * ʃʃ {(y^2} dydz [(z from -b/2 to b/2), (y from -h/2 to h/2)]
    and i get

    Mo=(σ*h^3*b)/(12c)

    now how do i find thevalue for c that will give me the maximum Mo?? if c=0 Mo is infinite ??

    i thought maybe to find the derivative and compare to 0 but by what? y? z? either way i dont see how that would help, since i am looking for the maximum "c" value, then i thought maybe dMo/dC but i dont think so.
     
    Last edited by a moderator: May 4, 2017
  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: Solid mechanics-how do i find the maximum momentum in this question?
  1. Did I do this right? (Replies: 0)

Loading...