Thermal stress of two peices of metal attacthed to two plates.

[larz19943]

Homework Statement

2)Both, a brass tube and the steel rod located inside the brass tube are solidly attached to common end plates A and B at either end.
The respective diameters are :

Do = 5.4 [cm]
Di = 3.0 [cm]
d= 2.8[cm]
Brass:
alpha=19x10^-6/degree celcius
E=210GPa
Steel:
alpha=12x10^-6/degree celcius
E=105GPa
Initially the assembly is stress free.
Now the temperature increases simultaneously for the brass tube and steel rod by 58oC. As a result the distance L between the two end plates will change.
Determine the resulting stresses in the brass tube and the steel rod, counting tension as positive and compression as negative.

Following Questions to be answered:
Stress in Brass in MPa
Stress in Steel in MPa

Homework Equations

ΔL/L=(σ/E)+alpha(ΔT)

The Attempt at a Solution

I solved for L in the equation above since the length is the same. then I pluged the know values in them but now I have a sigma on both sides and that is what I need to find out and I can't figure out how to solve it.

 

[SteamKing]

It's not clear, but is the distance between the plates supposed to remain constant after the temperature change?

 

[larz19943]

Yes but that distance is not given, the plates move a distance delta L apart after the tempature change.