South San Francisco, CA July 30, 2015 by Michael Harris
Get an older coat hanger, a thick one.
Open it up.
Grab a section in each hand.
Bend the coat hanger into a U shape.
You have just work hardened the steel in the coat hanger.
Next try to unbend the boat hanger.
This will work harden it even more.
It will get very difficult to bend.
It will finally become so brittle, it will break.
The more carbon in the steel, the quicker the steel get hard.
The Bay Bridge Bolt problem will not easily be solved.
When steel corrodes, it loses strength very quickly.
A very good small book on Material Science is the Harrison & Bonini bolt catalog.
I have the 65th edition (1946 – 2011)
I think it is current. It is 196 pages thick.
I used to pick these up when visiting the SF Hall of Injustice on Bryant Street.
I am down to my last one.
Boeing is now trying to cut expenses on the 787 jet by replacing Titanium with Aluminum.
The aluminum will corrode.
Assume steel $1 / lb.
Aluminum $4 – $12 / lb.
Titanium $25 / lb.
Mark, get Mel to help you with the coat hanger experiment.
Mel will most likely have stories to go with this that will come to mind.
Last year was the Ice Bucket Challenge.
This year is the coat hanger challenge.
I have just convinced South San Francisco’s Vice Mayor to try bending a coat hanger as a family project.
If I taught Engineering, it would be like this.