Design, Featured, General, Post of the Week / Wednesday, June 19th, 2024

When we first decided to make SOCKEYE out of carbon fiber, we knew there would be many new challenges. One of which being that, according to the rules of the solar car challenge, we would need to provide destructive testing data that justifies the strength and crashworthiness of SOCKEYE. 

So, while building the car, we made samples for a tensile strength and a three-point bend test. And, since a team member at the time was working a summer internship at Boeing’s destructive testing lab, we were able to have our samples tested there.

Carbon Fiber Destructive Testing Samples

The tensile strength test (stretching the carbon fiber lengthwise) in particular showed forces of approximately 9,000 lbf. We knew carbon fiber was strong, but this number was so high that we looked back at the car and compared it to our test. One thing we noted was that while the tensile force was implemented evenly across a bolt in the test, in reality forces would only be implemented from one side. Mounts for our roll bar, suspension, and more were all mounted in a way where the tensile force would only be implemented from one side of the mount. 

For this reason, we decided to run a second tensile strength test that implemented a force from one side of the bolt. Sure enough, this resulted in approximately half the tensile strength from the two-sided test. Still extremely strong, but more in line with what we expected.

At this point, we sent all the data we had over to the race organizers at the solar car challenge. They told us that while the data looked good, it didn’t tell them anything about our specific application of composite material (i.e. the car).

SOCKEYE’s frame and crush zones

To solve the question, we started work on an analysis of the crashworthiness of SOCKEYE. Little did we know, what initially seemed like a quick box to check would quickly turn into months and months of work. 

As we worked with this data to try and put together a defense paper, we realized there were missing pieces of the puzzle. It was difficult to describe how SOCKEYE would behave in a collision with only two tests. So, we consulted with Kurt Gustafson, who has been helping us with composites work throughout this entire project. He assisted us in running our own energy absorption and compressive strength tests so that we could better defend our crush zones and safety cell in the defense paper. 

With all the data needed, we got to work on a defense paper to send to the Solar Car Challenge officials for evaluation. To make sure the paper looks professional, we formatted it in a program called LaTeX, where you write your paper in code, and the program automatically compiles the document. This ensures that all figure numbers reference the right section, moves around images and tables to organize the pages, and generally makes sure the formatting is consistent and standard.

LaTeX In-Use

On June 12, 2024, we submitted the final version of the paper to the solar car challenge staff. After working on the destructive testing for nearly two years, and thanks to the help of numerous individuals (see acknowledgments copied below), it was a massive relief to hear the news that this document more than complied with the request of the rule. In brief, to answer the posed question, yes. SOCKEYE is more than safe enough to meet the rules of the solar car challenge. 

Acknowledgments – From Destructive Testing Report

First of all, I would like to give great thanks to Dr. Alain Semet, who has been a great mentor and supervisor throughout the entire project, and a mentor for the team since long before.

I would also like to extend a huge thanks to Kurt Gustafson, who took time out of his busy schedule to advise our engineering decisions, destructive testing, and ultimately with the creation of this paper.

My UWHS English Teacher, Marcie Wombold, also took time out of her very busy schedule to give invaluable feedback and a new perspective on the wording and organization of the document.

Of course, this also would not be possible without all those involved in the organization of the Solar Car Challenge. The team is extremely thankful to have been part of such an impactful program. This document is a compilation of years of work, experience gained, and lessons learned.

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