Case Study

Small school goes solar in a big way

Principia College

A small liberal arts college uses NX to design solar cars that beat the competition from much larger technical institutions

Liberal arts car designers

Principia College is a small liberal arts college with approximately 550 students. Although the college does not have an engineering department, its students are frequent competitors in solar-powered car competitions such as the North American Solar Challenge and theWorld Solar Challenge. Principia’s students don’t just make an appearance, however. Their cars are usually among the top-ten finishers, finishing well ahead of entries designed by engineering students from much larger colleges and universities.

“The students on Principia’s solar car team come from nearly every major in both the liberal arts and the sciences,” says Steve Shedd, chair of Principia’s Computer Science department and one of the two faculty advisors for the solar car project. “Part of the reason our car does so well is that our students are good at solving problems and thinking outside the box. Another reason is NX.”

Turning point

Since 1999, the Principia Solar Car Team has been using the NX™ digital product development system from Siemens PLM Software to design their cars. The outer shell, electrical system and “every nut and bolt” of the mechanical system are modeled, assembled and tested virtually before the car is built. This provides a huge advantage over paper drawings and clay models. In fact, the introduction of NX marked a turning point in the Principia team’s competitiveness, according to Shedd.

“We built our first solar car for the 1995 cross-country race,” Shedd says. That car was named Ra, after the ancient Egyptian sun god.“That car didn’t qualify,” he continues.“It wasn’t robust enough to pass all of the tests. The next year, we came in thirty-first out of 36 teams, and the year after that, we were twenty-sixth out of 29. Then we got NX – or Unigraphics, as it was called then – and since then, we have finished every race in the top 10.” Principia’s impressive record includes finishing second in the 2008 North American Solar Challenge.

Space age, satellite grade

Principia’s solar cars combine aircraftgrade composite construction with satellite-grade solar cells and solid lithium-polymer batteries. Each car is built on an ultra-light aluminum space frame chassis. The team of about 20 students designs and constructs a new car roughly every two years, improving on the previous model each time. The current car, Ra 7, features a completely redesigned battery pack, in-house custom circuitry to monitor and manage the battery pack, a steering wheel with a built-in LCD screen and a new carbon fiber body.

By representing the entire car digitally in NX, the students avoid fit and interference problems. They use NX motion simulation functionality to digitally test moving parts, such as the suspension system, before components are manufactured. The body design team finds ways to eliminate drag by using the NX data of the outer shell as input for aerodynamics analyses in the Fluent CFD package. NX data is also used to manufacture parts. “Our school doesn’t have CNC machines, but generous companies in the area machine parts and molds for us from our NX files,” Shedd explains.

Back when the school implemented NX, a number of students attended a training class, but since then, students are basically self-taught. “The students here are bright, and they know how to learn. That’s a benefit of a liberal arts education,” Shedd says. “They learn NX by using it.”

Great experience, exposure

Principia participates in two types of solar car competition: track races and transcontinental races. The winner of a track race is the team whose car completes the most laps in a fixed amount of time. A transcontinental race covers thousands of miles, can last as long as two weeks, and is conducted on public roads.On a sunny day, the top cars travel 250 to 400 miles at 45 to 65 mph.

Principia’s team has competed in the United States, Greece, Taiwan and Australia. In 2002, it was asked to be one of two solar car teams that represented the US in the China Solar Challenge and Road Show. Four students and two faculty members traveled through China for three weeks, demonstrating solar technology and sharing technical expertise. “The solar car project provides great experience for our students and great exposure for the school,” Shedd concludes. “And our relationship with Siemens PLM Software has been fundamental to our success.”

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