Duke University Motorsports is a student group that designs and builds open wheel, single seat race cars to compete in the Formula SAE competition sponsored by the Society of Automotive Engineers. The team consists of Duke students from both Pratt and Trinity, in all classes. The purpose of the team is to provide students with a way to gain practical design and manufacturing experience in a fun and challenging setting.

Sunday, June 9, 2013

Recap of 2013 Motorsports Car: Intake

I must say that I still haven't full recovered from the tornado that was the month prior to competition, which is why I haven't had the opportunity to update the blog. However, we did take a lot of pictures of the design and fabrication processes, so I would like to go through all of the progress we made as a team building our car, named OD-13.

Just a quick note: I apologize for any redundancy regarding the pics that may occur...I just want to make sure I cover everything, because there is a large gap in the blog.

I'll start with the intake:

This past year, we had a lot of trouble with the intake system. For some reason, the epoxy we were using would sometimes cause small imperfections, and then when we placed the entire intake under vacuum, those weak spots would cave in and case us to remake the intake (about 4 times total).

For the runners themselves, we stuck with carbon fiber because of the large radius of curvature and focus on lightweight design. In order to successfully do this, we had to use wax molds that we wrapped in carbon fiber, and then melted the wax out (we're looking to refine this process for next year).
The molds full of wax

Mmm tasty
 Once we got the hardened wax molds separated from the rapid prototyped molds, we wrapped them with 3 layers of carbon fiber and vacuumed bagged the entire set. It was at this point that we realized the intake plenum had a weak spot right in the middle, as it imploded under 25 inHg, which is wasn't acceptable.

Runners: Good! Plenum: Not so good...

 We redesigned the substructure so that it would have support at the points where it needed it the most, which basically had another structure in the middle. This was still a very lightweight, but sturdy option for us instead of adding extra layers of carbon fiber and epoxy.

New plenum support substructure

 At this point, we had a new plenum, new diffuser, and new runners, so we were ready to put it all together and seal it completely. We aligned everything, applied carbon fiber and epoxy, crossed our fingers, and pulled around 28 inHg of vacuum to simulate the worst case scenario from an engine loading perspective. Everything turned out great! No deflections, no weak spots, and we had an extremely stiff, but lightweight composite intake assembly.

 Once we had the intake, we then needed to machine fuel injector bungs and place them properly on the runners. Our design thought was to mount the injectors close to the intake ports so that the fuel would not compromise the structural integrity of the runners (we noticed that it weakened the runners over time due to large amount of exposure to the race fuel).

Aligning the injector bungs and the mounting structure

Final adjustments

 Once we got everything secured and sealed, the final product was ready to mount on the car!

Finished intake assembly

 Stay tuned for more updates...didn't want to put too many things on one blog post!

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