an engineer's guide to thermal expansion

[dtmarx@siu.edu (David T. Marx)]

I was talking with a full professor of mechanical engineering about how he
included  thermal expansion in some analysis he was doing.  He asked me if
I knew the thermal diffusivity, density, and specific heat of the material
in question.  I gave the values to him, but didn't know where he was going
with it.  He said, "well, we know the rate at which we're putting energy
into the system..."  He then proceeded to write out the following:
        (delta Q)/(delta t) = kA (delta T)/(delta x)
                                           = (alpha)(rho)cA (delta T)/(delta x)

        =>  (delta x) = (alpha)(rho) cA(delta T) / [(delta Q)/(delta t)]

Thus we have calculated the thermal expansion (delta x).

It was an education for me!

With regards,

David T. Marx, PhD
Associate Scientist
Center for Advanced Friction Studies
Southern Illinois University at Carbondale
Carbondale, Illinois  62901-4343

http://www.siu.edu/~cafs/