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Design, Build, Test. Repeat.

Design, Build, Test, Repeat.
Senior Sean Kuehn displays several of his team's wind turbine blade designs. Rapid prototyping has revolutionized SE 120, an undergraduate computer-aided design class in structural engineering. Students now design, build and test multiple iterations of their designs.

Jacobs School undergraduates learn this fact of engineering life while designing wind turbine blades in Structural Engineering 120. This undergraduate class gives students the chance to iterate on the design-build-test process thanks to 3D printers that enable rapid prototyping.

Students who take SE 120 with professor Falko Kuester get to design, model, simulate, analyze, print and then test their turbine blades. One team built and tested more than 16 blade designs over the course of several weeks. Structural engineering major Sean Kuehn was part of that team. You can calculate all day long, Kuehn explained. But your prototypes don't always do what you want them to do because in the real world, no assumptions are made.

Many of the student teams started with long slender blade designs that resemble the wings of an airplane. Testing their blades revealed that this design produces too much lift and not enough forward propulsion, which is what the blades need to generate energy. Kuehn's team tweaked their designs in many different ways, including making changes in the twist angle on the blade.

"I'm very excited to see the innovation, the spark that takes over when students get involved in a design project that includes rapid prototyping," said Kuester, who also holds a faculty appointment in Computer Science & Engineering. "Normally, there is a disconnect between the CAD world, the digital world and the physical world. In this course, we model a structure using CAD techniques and run simulations to determine how that structural specimen performs under certain conditions."

That's often where instruction stops. Kuester's students, however, go on to print and test physical prototypes of the models they have designed—and then incorporate what they learn into the next design iteration.

Mimi Ngo is a structural engineering undergraduate who took the class last year and went on to work as a lab assistant in subsequent quarters. "We learned how our structures failed. We had the opportunity to see if our predictions were accurate," she said.

"We always try to provide as much hands-on experience as possible in our lab classes," said Steve Porter, a senior development engineer who helped design the course and works closely with students. The project gives students a window into the economics of design, construction and engineering by tracking materials and building costs as well as energy production.

As part of the final exam, the undergraduate teams measured wattage generated by their turbine blades in the teaching lab's wind tunnel. A leaf blower mounted horizontally on a work bench generates the wind for the tunnel.

The students also test their blades—mounted to aluminum turbine towers they also design and construct—on a miniature shake table. The table simulates actual earthquakes that have occurred in California, Chile and Japan.

"You learn more in rapid prototyping classes," Kuehn said. "You screw up, you learn from it. You do better, you learn from it. In the end, you end up with the best design."

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