Aluminum fatigue life

[es61@prism.gatech.edu (Eric Schumacher)]

A brief thought on the long term use of Aluminum:

Fatigue strength/resistance is based upon an equation that relates the
forces applied (average and peak) to the number of cycles to failure.  For
steels, if your force averages and peaks are below a certain level, the
fatigue life of the component is infinite (notice I said fatigue life). 
However, for Aluminum, this does not hold.  In other words, no matter how
small the load applied to an Aluminum part, with enough cycles, it will
eventually fail.

Think about that the next time you are looking at an NSX, A8 or A4.  It
might also apply to airplanes.  


BTW, I'm fairly certain the engineers took this into consideration in
design.  Why do you think old US commercial airplanes fly in South America
for a good twenty years after we get rid of them?

Eric Schumacher