Quick post about the Troitsky Bridge Building Competition. Tim, Griff, Omar, and I went to Montreal to compete in this popsicle stick bridge building competition. Having gone last year, I was super excited for this year because we knew what to expect and I had a plan (since September!).
Rules:
Only materials are popsicle sticks, white glue, dental floss and toothpicks
Pieces must be able to fit into a 500mmx400mmx350mm "box"
Clear span of bridge: 1000mmm to 1200mm
Freeboard of bridge: <= 150mm
Overall length: <=1350mm
Deck height: <=450mm
Mass: <6kg no deductions, 6 < m <10 kg minor deductions, >10 kg you're ridiculous
Back in September, Tim and I made some test popsicle stick pieces to see how to best glue the popsicle sticks together. We waited for the pieces to dry and tried machining them in the band saw and putting them in the lathe, which were all successful and allowed for a more elaborate design. We also took a density test so that we could estimate the weight of the bridge before we even built it.
I drew everything up on Inventor for 3D purposes, made drafting plans of the pieces, and using the density, I tailored it until it was just shy of 6 kg so that we wouldn't go over with the dental floss or accidental extra weight. And then nothing happened until mid February...
Since I was in Concrete Toboggan, I had to wait to work on Troitsky, so once February 12th hit, I was in popsicle mode. Actually, because the week after GNCTR was hectic trying to catch up and write more exams, it started on reading week. So of the 6 days of reading week (closed the family day weekend), I think I spent all but 1 or 2 on campus working to some effect. Tuesday morning I got down to work and started glueing the tension members (the horizontal bar of the 'A' frame). These were some of the highly critical pieces so needless to say I was a little nervous because I didn't know how best to start. Turns out, organizing the first layer is important and tricky since there's nothing to secure them. I was lucky that for the dimensions of the tension members, the width was half a popsicle stick, so all I had to do after I cut off the rounded ends was to pass a few sets through the band saw again to get half pieces. It was basically cross laminated for simplicity. I got help from John in the afternoon which sped up the cutting and gluing process. In order to tie the tension members together, I built a second piece (one popsicle stick long, a 40mmx40mm cross section) that went perpendicular to the member so that the floss had something to wrap around. The tension member was built to have a hole that size to insert it, so at the end…it looked like a set of crossbows. Another thing done during the reading week was the design of the logo and the background for our display. Unlike concrete toboggan, we did not require technical data or analysis, so I took a picture of a ship, "Queen Anne's Revenge", sketched in AutoCAD and colour filled in Photoshop. No copyright issues!
The basic idea of the design was to achieve a quick install time for the day of the competition. The compression members connected to each other (at the peak of the 'A') and to the top of the tension members with dowels. The tension members were also doweled together and to the base plate on the pier. The piers themselves were hollow. The deck was supported on a flattened portion of the compression members and thin deck supports on the ends that were secured with notches into the underside of the deck.
So after spending way too much time in the machine shop cutting, glueing and machining, we were off to Montreal on Thursday after the dynamics class. It was great evening in comparison to last year because we pulled an all nighter trying to build the bridge pieces in our hotel room. This time we were able to go out, but that consisted of hanging around at the hotel for a bit, going with a group of people back and forth on St. Catherines because the events were over or the bars were full. À la GNCTR, we ended up back at the hotel, socializing in the hallway. We got kicked out by security, and Tim and I retreated to our hotel room, we lost Omar to visiting his Montreal friends and Griff to somewhere else in the hotel. Tim shoved himself under a bunch of sheets while he laughed at the audio from me watching anime (Natsume) and talking to John on Facebook about stuff from my applied math biology course. Griff came in much later, proclaimed 'I am so hammered', left again, and then came back 1/2 hour later to say 'I am so wasted' and was back to stay. Crazy times :P
Friday morning we got ready for the competition, sans Griff until a little while later for recovery purposes. Building went really well, We had three boxes of dental floss going together as one strand and being wrapped around the tension member "nubs" in a figure-8. The only thing we had to modify was to increase the height of the piers by one popsicle stick because there was a slight sag in the tension members even after being doweled on its ends and wrapped up in floss. Here's what our bridge and display looked like!
Crushing ceremony came in the afternoon, and some of these bridges did fantastically. Now, of the 34 teams, apparently 27 of them did 'A' frames because it's the tried and true design, so the creativity wasn't always there. As for our team, we got to 288 kg when we got a member failure (the dowels were ripping out of the inner face of the compression members where they meet the tension members). Since the crushing ceremony demands destruction, Tim smashed it on the ground since the "crusher" shaft was getting bent and they no longer were crushing until total failure. The machine still broke on the last bridge, the automatic number one team, the League of Extraordinary Gentlemen. Even though the highest load from another team was 2500kg, they were at 2100kg and no sign of giving up when the "crusher" actuator gave up.
That night was the dinner and awards at La Cage aux Sports at the Bell Centre. The event got the entire bottom floor, so many engineering chants, beer, and popcorn everywhere. Thanks to GNCTR, I knew the cheers and could follow along :P. But after a while I had had enough, so like last year I slipped out after the dinner and headed the other way. A bunch of the Carleton alumni spotted me and asked where I was off to. I said '...out' to which Tim replied "she's going swing dancing" with a very matter-of-fact tone. Apparently that caught the attention of one of the Carleton alumni cause he used to be part of swing Dynamite and does west coast now, so he came with me to Cat's Corner. I had a blast, I just needed a bit of a different vibe than the drinking yelling group and just get to dance a bit.
When I got back to the hotel around 1 ish, I was in the hotel room for a bit but it quickly became busy so I headed upstairs to where Tim and the Carleton alumni were. Locked out of my hotel room, I was forced to be up until 3:30, and after having danced, I just wanted to sleep. First I checked the door, and the bolt was over the door, I go back upstairs in a determined tone saying "Tim, pass me our tension member, I'm getting into that room", but he came with me and so did one of the alumni because he was amused. Turns out people left our room in that time and I was able to curl up and go to sleep finally.
Overall I really liked this year's competition, much less stressful than last year, so more fun! I don't think I'd want to participate again (even if I could), but I'd be totally up for mentoring a group of undergrads if they are interested. They don't need to build a terrible bridge like we did last year. I leave you with our 2010 attempt, oh the colourful horror.
