Principle Second Moment Of Area - L shape.

[Roomie]

EDIT: I meant to place this in Engineering help. Would a moderator please move it there? Thanks.

Homework Statement

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

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

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

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 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
Page 2: http://dl.dropbox.com/u/630750/6.jpeg

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=1.24x10-9If anyone could check this and see where I've potentially gone wrong I will be hugely grateful.

 

[Roomie]

Anyone?

 

[Roomie]

EDIT 2: I've sorted this now. Please Ignore.

EDIT: I meant to place this in Engineering help. Would a moderator please move it there? Thanks.

Homework Statement

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

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

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

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


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
Page 2: http://dl.dropbox.com/u/630750/6.jpeg

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.