A Bridge That Couldn’t
Catch a Break


October 2013

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You might think there’s no such thing as an unbreakable bridge.

Well, someone should tell that to an undergrad student team at Brigham Young University, as they built the first one to withstand the “breaking test” in the history of the International SAMPE Bridge Competition.

It started with a class and two assignments, says team member Jake Merrell. “It was on composite material design. One project was to build a bow [as in a bow and arrow], and the other was to build a bridge for the state SAMPE competition.”

According to SAMPE’s website, “The objective is to design and build a composite bridge using an assortment of pultrusions, cores, fabrics, and other materials supplied in kit form.”

For the state competition, the four-member team used finite analysis programs to work on shells while assessing height, with the top and bottom of the bridge being optimized, among other things.

Merrell knew they didn’t have as much experience as some competitors but still felt theycould have a good showing. In the end, they actually took second place—a great finish, but not one that makes you think an unbreakable structure would be next.

But it was.

Made out of bamboo fibers and epoxy, BYU’s bridge won second place at the SAMPLE competition. Image: BYU.edu

 

Going International

For the SAMPE International Competition, they’d have to step up their performance or risk getting blown out of the water. According to SAMPE’s website, a total of 61 miniature structural bridges were submitted from 17 colleges and universities. Though many of the schools were from the U.S., competition came from as far away as Harbin Engineering University in China.

Merrell remembers working on a model for the competition for around 30 hours to optimize the weight and make sure it stressed in a uniform fashion. Hand calculations also were scrutinized to see if they’d be sufficient. Taking the bridge to a composite lab to lay it up, they ended up making it 1.5 times thicker with more carbon fiber than the regional design. “What we learned from the first bridge was that manufacturing was critical," he says. "We rolled up carbon fiber, added more plies, making improvements wherever it could be done.” They also made sure to trim it so all plies would be flush with the edge. “We did it a lot cleaner," he adds. "[We were] much more confident in it.”

Then it was time to send it off to competition with their professor, and wait. When word got back to them that it didn’t break, the team was elated.

But despite creating competition history, they would have to settle for third place.

Building Bridges

The event had weight as a factor and their entry was on the heavier side, Merrell admits. Still, it didn’t dampen their spirits. Merrell realizes what many creators do: much of the reward is in the work itself.

“I like the fact you’re using tools (for the competition) and getting a chance to understand tools better,” says Merrell, now a graduate student in mechanical engineering at BYU. “These competitions relate to practical fields and you can actually see the results of your calculations and make adjustments.”

In other words, Merrell and his team members may not be building bridges for a living, but their effort and experience might just build bridges to many other opportunities.

Eric Butterman is an independent writer.

These competitions relate to practical fields and you can actually see the results of your calculations and make adjustments.

Jake Merrell, Brigham Young University

 
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