TO: Tim Cavanaugh, P.E., VP of Structural Engineering
RE: Volunteering at the STEM Career Day at my son’s middle school
STEM Career Day at my son’s middle school was a huge success! Who would have thought kids would be so excited to discuss structural engineering concepts with a boring old engineer like me? They immediately waved their friends over to my exhibit as soon as I started describing linear elastic deformation in steel shafts — and perked up even more as I wrote Hooke’s law on the board:
Force = Stiffness Factor * Extension
In simple terms, I explained that pulling on a shaft always increases its length.
Then I showed them how the Stress Formula is used to calculate the load that the shaft can handle:
Stress = Force / Area
One bright boy then asked me to clarify why thicker shafts are better. I explained that a larger girth has a larger radius of gyration and makes a shaft more resistant to bending. Final result: a very stiff rod.
I couldn’t contain my enthusiasm teaching them that exceeding a steel shaft’s elastic limit results in permanent plastic deformation. More questions about plastic behavior resulted in a detailed description of necking. The kids were fascinated to hear that, after a lot of tension, once necking begins, yielding is sure to follow.
As the size of the crowd increased, I introduced my master’s thesis topic: sheet metal roofing. A very nice boy asked me about ribbed steel — the very subject of my recent article in ASCE Civil Engineering Magazine. I must have been grinning ear to ear as he astutely asked, “So would you say that ribbed increases your pleasure?” Heck, yeah, it does!
By now, every single kid in the auditorium was at my table! I wanted to end with a bang, so I finished with a demo on hardening steel shafts. The crowd went wild as I fired up my blow torch and showed them that once things get really hot, you can quench the shaft by submerging it in a lubricating oil. Ta-da: shaft hardening!
But by far, my proudest moment was at the end. The kids begged me to come back next year. I told them I would come over and over again! There is nothing more rewarding than turning kids on to the joys of the noble profession of engineering. My son was nervous that I would embarrass him, but I am happy to say I proved him wrong! As they left the auditorium, you should have heard those kids chanting my name!
Woody Johnson, P.E.
Senior Structural Engineer