Formula SAE is a year long project where a multi disciplinary team of engineers design and build a formula car to compete in the Formula SAE competition. I designed and manufactured undertray and diffuser which creates down force on the vehicle. Downforce was produced by a low pressure region under the vehicle. This low pressure region is created by the expanding the air flow cross section in the diffuser which then forces air to move at a higher velocity under the vehicle by conservation of mass. This high velocity air flow creates a low pressure region by Bernoulli's principle.
The 2016 undertray and diffuser were worth over $1000. The undertray was created in computer aided design (CAD) using Siemens NX 8.5. The 2016 undertray design reduced the drag produced by over 17% over the previous model and increased downforce by over 7% over the previous model. To determine the drag and downforce values I performed computational fluid dynamics (CFD) using Star CCM+.
The undertray consisted of 4 layers of carbon fiber with a divinycell core to provide structural integrity. The carbon fiber was laid up on a mold for the undertray. Resin was applied to each layer of carbon fiber and then the whole mold was placed inside a vacuum bag and remained under vacuum for several days. Once removed from the vacuum bag the undertray had to be trimmed and have steel mounting brackets attached.