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!

Homework Help: Principle Second Moment Of Area - L shape.

  1. Jan 11, 2012 #1
    EDIT: I meant to place this in Engineering help. Would a moderator please move it there? Thanks.

    1. The problem statement, all variables and given/known data
    I need to work out the theoretical principle second moment of area for an L shaped specimen I have.

    http://dl.dropbox.com/u/630750/Screen%20Shot%202012-01-11%20at%2013.20.50.png [Broken]

    I have attempted this but I'm getting an answer thats way off the experimental data.

    http://dl.dropbox.com/u/630750/Screen%20Shot%202012-01-11%20at%2013.11.07.png [Broken]

    I first have to work out IA, IB and IAB for this specimen.

    Then convert it to Ix and Iy using a Mohr's circle. (The principle second moments of area)

    http://dl.dropbox.com/u/630750/Screen%20Shot%202012-01-11%20at%2013.13.53.png [Broken]

    2. The attempt at a solution

    I've made an attempt at this by splitting the L shaped section into 2 parts.

    Here is my attempt:
    Page 1: http://dl.dropbox.com/u/630750/5.jpeg [Broken]
    Page 2: http://dl.dropbox.com/u/630750/6.jpeg [Broken]

    I then used these on a Mohr's Circle to work out Ix and Iy, and I got those to be Iy = 1.2x10-9 and Ix=1.24x10-9

    If anyone could check this and see where I've potentially gone wrong I will be hugely grateful.
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Jan 12, 2012 #2
  4. Jan 12, 2012 #3
    EDIT 2: I've sorted this now. Please Ignore.

    Last edited by a moderator: May 5, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook