Formula SAE Projects

One of the key deliverables for the Formula SAE Electric competition held annually at Michigan International Speedway is a set of three-view engineering drawings showcasing the car and its most notable features. As one of the team's most senior mechanical members with extensive experience making engineering drawings, I volunteered to fulfill this deliverable for the 2024-2025 season.

In addition to mandatory inclusions such as overall vehicle dimensions and basic information, I also consulted every design section on the team to select one notable component or subassembly which best highlighted their greatest accomplishment this year. This way, every part of the team was fairly represented and had their hard work displayed, both visually and through a short caption.

My primary goal was to earn full points for the team on this deliverable. However, the best drawings among all teams will earn further recognition: being printed in large format and displayed for all competition participants to see in person. I am eagerly awaiting the release of scores to see whether I fulfilled either of these objectives. Regardless, I am very proud of my work and how it showcases both our latest technological developments and my proficiency with creating effective engineering drawings.

As part of a major suspension design goal of reducing unsprung mass for the 2025 car, I focused on overhauling the oddly heavy front hub design. Among other changes, I simplified the main shell's structure, greatly increased the fillet radius at the critical bearing shaft transition area to reduce the stress concentration, and developed a new reinforcement rib geometry. This resulted in a 31% savings, eliminating 171 g of unnecessary material per side. Additionally, by starting fresh and first defining the layout of critical features before modeling anything else, I corrected for the scrub radius being around 10mm larger than intended. This previously unnoticed error very well could have caused the unexpectedly high steering torque and vehicle dynamics model inconsistencies which the team has been troubleshooting for several years. Thanks to a rules clarification for the 2025 competition season, we also returned to a floating rotor setup where the rotor is not rigidly joined to the hub. This accommodates for machining tolerances and helps mitigate thermal warping.

While designing, I always have in mind the question "how will this part be made?" As such, I carefully shaped the stiffening ribs to be machinable on a 4-axis machine despite their complex appearance. The resulting design's stiff yet lightweight structure is well worth the increase in complexity over a 3-axis setup for instance.

Along with my new front hub design for the 2025 car, I designed these 6061-T6 aluminum castle nuts to retain the wheel bearings and Hall effect ring while also applying axial preload. Although dual-row angular contact bearings do not strictly require preload, decreasing their internal clearance via axial compression of the inner race resulted in measurably greater rigidity, albeit at the cost of a higher wear rate and slightly more frictional losses. Due to the car's fairly short target lifespan, I deemed this trade-off to be desirable.

The thread size of 1 3/8" - 12 UNF was chosen for two main practical reasons:

• Its major diameter is 34.93 mm, which works well with the 35.00 mm hub shaft.

• The university machine shop owns the appropriate tap, which would be significantly easier to use compared to single pointing the threads.

I then performed threaded fastener calculations to ensure that stress values were acceptable and that joint separation would not occur under any driving conditions. To positively retain the castle nuts, the ten cotter pin holes in the hub shaft and six slots in the castle nuts resulted in 30 unique increments per revolution. This 71 μm resolution allowed for fine adjustment of bearing stiffness versus rolling resistance.

Lastly, I machined the parts using a manual lathe and 3-axis mill. The design minimizes the number of measurements and setups required, which helped me easily achieve tight tolerances and finish the job quickly.

Toe is a measure of how angled a car's wheels are about the vertical axis and is important to quantify when setting up the car for maximum performance. Although laser-based equipment is often used commercially, the simplest and cheapest method for many FSAE teams is to run a piece of string parallel with the car's longitudinal axis on each side of the car, and then measure the toe angles with respect to those lines. I designed this tool to support the ends of the strings in space and control their spacing to ensure near-perfect parallelism.

My goals were to make the system simple and intuitive to install and use while still ensuring complete functionality. At the front, my final design uses two dowel pins through the front wing mounts. At the rear (pictured), the two beam-like pieces first hook under the chassis and then snap onto the orange jacking bar. Lastly, the metal tube slides on via tapered dovetails (shaped to only work in one orientation) and captive thumbscrews (to avoid losing parts).

When testing prototype designs, I would ask team members to try installing the parts without any guidance to help me eliminate possible sources of ambiguity and confusion. Another point of interest is the hose clamps which connect the tube and mounting pieces. Since they are meant to be more or less permanently affixed, I oriented them such that they are difficult to access when the system is mounted, dissuading users from fiddling with them.

The Ackermann links serve as an easily replaceable adaptor between the tie rods and uprights to facilitate changes in the car's steering and handling characteristics. As they were previously solid aluminum plates, I wanted to optimize them as much as possible. The overall result was not massive (20 grams per front corner), but this was still an excellent learning opportunity for leveraging technologies such as topology optimization and generative design to help me in the mechanical design process. The design was truly validated after these fragile-looking parts survived hundreds of kilometers of testing and two competitions without showing any signs of damage.

Due to a rules change, we needed to change the brake rotors from being floating (as on the 2023 car) to being rigidly mounted on the 2024 car. While merely being a modification and not a total redesign, this was my first major design task on the team and I was entrusted with the drivers' safety and their confidence in the braking system.