Friday, November 12, 2004

Fun In the Structures Laboratory

That's right, they let us into the structural testing lab this morning. We got to see an interesting demonstration of a wooden beam failing in shear, as well as some other chunks of wood failing under compression. Basically we snapped stuff and squished other stuff. Not that these were small pieces of wood though - they were all 10 x 10 pieces. It takes an insane amount of pressure to fail a 10 x 10 piece of wood, but the machine we used can generate up to 12 million pounds of force. So it was no big deal. The machine was quite impressive though. Installed in 1961, it is still the largest machine of it's kind in Canada. It can test objects that are up to 20 meters long, 3 meters wide, and 7 meters tall (the size of a double-decker bus). And yet it is sensitive enough that it could measure the force it takes to crack an egg. The concrete floor under it is something like 5 feet thick, so it can take the force of a test that would actually use the full 12 million pounds that it's capable of.

Seeing the wood being tested was an interesting experience. The first piece we tested was a 10x10 beam that was about 2.5 meters long. It was kind of like snapping a stick over your knee, except on a much larger scale. And it took several minutes for the snapping to complete. The next piece was a chunk of a 10 x 10 that was loaded perpendicular to the wood grain. It was literally "squashed", probably down to about 60% of its original height. Next we tried squishing a piece parallel to the wood grain. This one was much stronger, taking over 1 MN of force before failing. I got a piece of that one as a souvenir (I deserve it; it snapped off during the testing and nearly hit me).

I was going to upload pictures, but unfortunately Photoshop has decided that it wants to be a bitch. So maybe later.

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