Civil engineers pump energy into machines

Start with a little sawdust. Throw in a flywheel, some pulleys, a pendulum, a ball and lever, and you’ve got…not just a gizmo, but also a vehicle for teaching engineering design to civil and environmental engineering sophomores, who spent part of the year working on a class project, then worked up to designing and building their own machines.

"Our fourth mechanics lab assignment was to build a motion machine, a gizmo, a Rube Goldberg-type contraption--the coolest project we’ve come up with thus far to for this assignment, which teaches practical concepts of construction and provides shop instruction" explains Jack Germaine, senior research associate in the Department of Civil and Environmental Engineering (CEE), as he guides a guest through the workshop where a dozen or so students busied themselves assembling their final projects--energy harvesting machines.

Germaine taught 1.102 Introduction to CEE Design II this spring, along with lecturer Jessica Banks and technical instructor Steven Rudolph. Germaine is describing a lab assignment tackled by the students in March. The teachers didn’t reveal the product to students beforehand. Instead they handed out shop drawings of 150 pieces--labeled easy, medium and hard--and asked students to read the drawings, use the appropriate shop tools, and prepare pieces to the satisfaction of the "inspectors"

"We had people who had never put a screw into a hole, who have now mastered the drill press, cutoff saws, welding, etc" said Germaine.

After two weeks, students graduated to subassembly, and were given drawings that required assembling seven to 10 pieces at a time, and proceeded from there until the class had built a full-fledged thingamajig that did, well, just what it was meant to--throw the sawdust back at you. In spite of the lighthearted theme, the project provided valuable experience in craftsmanship, mechanics, fabrication, physics and team building.

Those same students ended the semester by showing off their own energy-harvesting machines around campus: six original designs that convert kinetic energy to electrical energy via a generator, which then powers a device of some sort. That assignment--design and build your own machine--followed the distributed energy-harvesting theme of the semester.

"Energy is a powerful common element to use for teaching the 1E and 1C students" said Germaine, referring to the environmental engineering and civil engineering majors. Both undergraduate majors take the same core curriculum sophomore year. "If you integrate energy considerations into all of the things that you do in the building process and make the product more energy efficient--you get something more marketable. For instance, if someday these students are designing a building, maybe they’ll design it with a combination of solar panels, wind mills, and passive underground storage resulting in a dramatic reduction in the energy footprint of the structure"

He motions to a large box with what looks like the curved blades from a barber pole standing on it. This is a triple-helical windmill designed to catch wind coming from any direction. "These vertical windmills could potentially be built into the exterior corners of a building to catch wind diverted by the structure, and use that to generate power" said Germaine.

Another student designed machine, the erg or rowing machine, was an enticing enough product idea that a manufacturer (Concept 2) donated a $3,000 machine. The students modified it with an attached generator that supplies energy to charge the battery of the coxswains box while the rower trains. As you might suspect, that student team contained a few members of an MIT crew team. The final product is on its way to the MIT boathouse for long-term evaluation as a potential commercial product.

The other four projects are a merry-go-round that powers a light show mounted on top; a stationary bike that generates enough power to operate a laptop computer, while the user gets her daily exercise; a traditional windmill tested at the MIT Sailing Pavilion; and the "Power Peddler" a stationary recumbent bike with a bright white boat seat mounted on top. The Peddler powers its own CD player.

Students displayed their machines the last two weeks of the term, inviting community members to take a spin on the merry-go-round in Lobby 7 and row on the erg in the Stata Center. Germaine said that one of the objectives of the course was to increase public awareness of energy issues. The students used feedback from the community demonstrations in their final project evaluations.

"I am always extremely impressed with the creativity, enthusiasm and thoroughness our undergraduates bring to any task" said Germaine. "I believe they set a very high benchmark for the level of effort and the quality of the prototype products. In addition, they gained a first-hand experience in the design process--the reality that no single solution is correct, that non-technical factors can impact the product, and that there’s plenty of opportunity for frustration. But we still had a great time. Labs can truly be memorable experiences"