Innovating and hands-on experience with Illini Solar Car

Hello! My name is Peter Walker and I’m a senior in materials science and engineering. 

One project I worked on was manufacturing the bottom shell of Illini Solar Car’s new car Brizo. I switched majors from Interdisciplinary Health Sciences with pre-med ambitions to Materials Science and Engineering my sophomore year. I joined the Illini Solar Car team to catch up and gain hands-on engineering experience. My first year on the team, I gained an understanding of the team dynamics and the goals for building the new solar car. I also learned how to manufacture fiberglass rods, and perhaps most memorably I spent weeks hand sanding and filling in indentations on a large foam mold. It was long, monotonous physical work, but it prepared me for other difficult projects. 

The bottom shell of the new car was designed by Nino Cirrincione, now an alumnus working at Ford. After designing the shell, the team glued several foam pieces together into a large block of foam which was sent to a company who cut the design of the car into the block to create the foam mold I mentioned sanding. After sanding and priming the foam with a coating, by my junior year, we had a nice surface to create fiberglass molds for making the bottom shell. Because of my materials science interest and sanding dedication, I was selected to be Composites Team Lead my junior year. The composites team is focused on working with fiber reinforced polymer composite materials, primarily fiberglass and carbon fiber. 

One of the largest projects of the year was manufacturing the bottom shell of the new car. To get an idea of the physical size of the shell, solar cars are as large as normal cars (and must be street legal) and the bottom shell of the car covers everything except the top surface of the car. Members from all groups of the team – mechanical, electrical, array, business, and media – pitched in to help in many ways from obtaining materials to completing the hands-on work of physically making molds of the bottom shell and the bottom shell itself. For some background on fiber-reinforced polymer composites, the materials use fabric with extremely strong (and expensive) fibers (usually fiberglass and carbon fiber) to reinforce resin, which results in a strong overall material. These composite materials are great for automotive and aerospace applications because of their low weight and high strength. Carbon fiber composites tend to be slightly stiffer and lighter weight than fiberglass (but of course more expensive) so they are generally preferred for something like a race car.

During manufacturing, resin is spread across the fabric in liquid form and then chemical reactions caused by the mixing of resin chemicals result in the hardening of the resin and therefore the whole material. The process is sort of like papier-mâché. Some of these chemical reactions also require heat from an oven to occur to harden the material. Additionally, the resin may be spread by the manufacturer of the carbon fiber or fiberglass fabric, which is known as pre-impregnated or prepreg composites, or the person making the composite part may spread the resin over the fabric, which is known as a wet layup. Generally, pre-preg composites are lighter weight, easier to make parts with, and look nicer because the manufacturer has optimized the fabric and resin. However, pre-preg composites are more expensive than buying separate fabric and resin for a wet layup.
We decided to make the composite molds out of fiberglass using the wet layup process and the bottom shell of the car with pre-preg carbon fiber materials. This would save money on the molds and allow us to have a nice carbon fiber bottom shell of the new car. The only problem was we did not have materials and had a tight budget. We had to get most of the materials donated and paid for what we could.

During the month of October, when we were trying to complete a critical first large step of manufacturing the composite molds, we could not spend any money due to a freeze in our budget. We were still in need of a large amount of materials at this point, so this led to a lot of emailing and calling companies to ask for sponsorships. The materials we were able to obtain were not exactly what we wanted, but they could work, so we tested potential workarounds such as mixing resins and mixing carbon fiber (that we were planning to use for other parts) with fiberglass. We tested the mold materials on a small scale with an oven that used lightbulbs as heaters. The tests were successful, and we proceeded with the molds. After lots of planning out the project and foam mold preparations, the team and I spent two 17-hour workdays completing the wet layup of the two composite material molds for each half of the bottom shell. The wet layups had to be completed in two days because the resin became unworkable after about a day, so each of the two molds had one day to be worked on. The next step was repairing the composite molds.
There were many indentations on the molds because of inadequate materials and mistakes during manufacturing. The indentations needed to be filled in and sanded smooth before proceeding to use the molds for manufacturing the final bottom shell of the car because every indentation would appear on the exterior of the car. The team spent much of fall break repairing the molds and building a wooden frame to support them while they were baking in the oven. Then, after these and other preparations the molds were ready for manufacturing the bottom shell, but we had one more challenge: vacuum bagging. Vacuum bagging involves sealing a composite part in plastic and then sucking the air out of the plastic to press the composite part smoothly across the mold.

We were lacking materials for this process. However, I realized that we only needed a few specific materials which we had enough money for. This allowed us to begin the project during the middle of finals week. The process took about 5 days of staying up till 4 AM and waking up at 8 AM. The bottom shell part came out of the oven looking very nice and the last few team members, including myself, who stayed till the end of the process were able to go home the day before Christmas Eve. Then, throughout the spring semester among other projects like the top shell, the carbon fiber chassis, and the windshield of the car, the composites team worked on making cutouts to the bottom shell for wheels and ventilation. We also spent much of spring break sanding the natural carbon fiber texture to make it smooth so that it could be wrapped in a paint alternative which is much lighter weight than paint. This is where the car was left off for a while as spring break brought Covid-19 measures into place.

After three months, we have started to resume work: wrapping the shell, fitting the chassis into place, and some other small touches. The safe restarting of progress appears to be a promising step towards fully completing the car. The project was certainly an eye-opening experience. I gained an immense amount of hands-on experience. I feel more confident utilizing tools and solving problems to create a product. I developed project management and time management skills managing to manufacture the bottom shell of the car during the middle of finals week. This project also gave me an understanding of the benefits and difficulties of fiber reinforced polymer composites. One large aspect of the project was learning the science behind the materials for proper processing and for use in situations where they generally would not be used because of the team’s limited budget. Perhaps, I will go into a career in the automotive or aerospace industries researching and developing more economically viable and eco-friendly fiber-reinforced composites to create light weight, efficient vehicles. One area I am interested in is natural fiber reinforced composites made of materials such as flax fiber. I also hope to pass on my knowledge to younger members of the team so that the future process is more efficient and less physically laborious. Lastly, I would love to see what UIUC project teams could do with more funding and help from faculty who have encountered similar challenges. Instead of students utilizing their engineering knowledge to work around budgetary issues and spending days completing physical labor on their projects, with more funding students could focus their knowledge on generating first place race cars, sustainable houses, advanced robots, and more. There is a great tradition of research at UIUC but the innovation from project teams is also extremely vital for producing industry-ready engineering students and often these teams are asked to prove themselves with little financial backing, faculty resources, or workspace.