Modeling, Analysis and Design of the Formula SAE Aerodynamics System

Introduction:
Formula Society of Automotive Engineers (FSAE) is a design competition in which students from more than one hundred universities design, build, and race their own formula style racecar. When it comes to the design and manufacturing of the components for the vehicle, one of the most crucial additions concerning performance is the undertray. Previous PNW Motorsports formula cars have not utilized an undertray. This team plans to improve the performance of the vehicle by implementing such a device to increase downforce, which allows for better wheel traction and stability while handling corners. The undertray will be made of carbon fiber. Preferably, the manufacturing of the undertray will be done by an outside source who can best follow design specifications in a shorter time. If this proves too costly, the team will develop these parts by hand-crafting molds through the use of foam cutouts. This project is critical to the future direction of PNW Motorsports FSAE teams. It introduces a critical component which will lay the groundwork for future aerodynamic pieces such as front and rear wings.
 

Significance of the Problem (Rationale)/Literature Review:
    Significance: The design of a Formula SAE racecar undertray begins with an understanding of computational fluid dynamics, finite element analysis, and vehicle aerodynamics. In the addition of such a system, one must consider how to achieve the best performance from the car. Producing a creative and critical design for an aerodynamic undertray is key to making a competitive racecar. Utilizing software, such as SolidWorks, ANSYS Mechanical/Fluent, and MATLAB is also crucial to simulating stress and optimizing a design to prevent failures on race day. The goal when working with such designs is to maximize performance boosts while maintaining a balance between keeping weight additions to a minimum and following safety requirements.

In FSAE competitions many of the highest-performing teams implement undertrays to add downforce and reduce the drag on their vehicles. Increasing downforce simply means the car will have greater traction when taking turns at higher speeds. It also affects the friction between the tires and the track, ultimately raising the top speed of the car. Previous PNW Motorsports teams have not added an undertray to the vehicles and have suffered in placing competitively because of it. In order to contend with top-tier teams, an undertray must be added to this year’s formula racecar.

Hypothesis and/or Objectives:

Design and fabricate an undertray for the PNW Motorsports’ Formula SAE racecar. As the first addition of an aerodynamics system to the car, it will be effective in improving vehicle performance, stability, and handling. This will give direction to future FSAE teams in developing and optimizing a full-body aerodynamics kit. Further, it will yield the opportunity to compete with other high-level teams in the May 6-9, 2020 FSAE competition in Brooklyn, Michigan.

Research Design, Methodology, and Activities:
The undertray design is expected to be finalized by the time of PNW Motorsports FSAE design reviews in the second week of December 2019. This will include optimization from analysis based on computational fluid dynamics (CFD) and finite element analysis (FEA) as described above, as well studying how the undertray integrates with the full vehicle assembly. Research will be carried out on standard undertray setups and 3D components (such as the diffuser), methods of implementation, and manufacturing techniques/materials at the typical FSAE university level. Design specifications will drive towards ease of manufacture, affordability, and low weight. System modeling will be undertaken in SolidWorks, and CFD / FEA in ANSYS for aerodynamic and failure observations. Following research, design, and analysis, the manufacturing of the undertray can be pursued. The system will be manufactured most efficiently and accurately if performed by an outside source for both molds and undertray.