1. Jul 12, 2015

### MrJoseBravo

1. The problem statement, all variables and given/known data
http://prntscr.com/7rw2hj

2. Relevant equations
deformation = PL/AE
A= pi/4 (d^2)

3. The attempt at a solution
The displacement of the shaft is equal to the summation of the displacement of each individual piece. I started on end A, and got the internal force to be 6kips
then
deformation at AB ~ 6x50/(9pi/4 x 18x10^3)
= .0024 in

for the middle shaft i got the internal force to be 2 Kips ( this could be where i am wrong, im not completely sure im doing these FBD's right.

deformation at BC ~ 2x75/(pi x 18x10^3) ( the 4's cancel out)
= .026

internal load at CD is 1Kip

deformation at CD ~ 60/(pi/4 x 18x10^3)
= .042

for the last two calculations, i believe they are off by a power of 10...and i cant figure out why.

I have attached my FBD's also, thanks in advance

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2. Jul 12, 2015

### Engineer at UIC

You just did the math wrong; 2*75/(pi*18000)=.0026 not .026

3. Jul 12, 2015

### MrJoseBravo

thats ridiculous.
Did i have the fBD's correct?