ERAU Motorsports, FSAE
I became team lead of our Embry-Riddle’s Formula SAE team during my 4th and final year of undergraduate. We learned a lot that first year about what it takes to fund, design, and build a car. This lead to our second FSAE car (ER-02), which was the first car we took to competition.
Below is some of the design and engineering work I did for the vehicle dynamics and suspension of this car.
Everything Starts in Modeling
Tires
Everything starts with tires and the suspension in a FSAE car is designed to keep them as happy as possible. We used force/moment and temperature data (shown above) to choose the best compound and suspension geometry to maximize the grip of the car. Temperature was especially important since we tested in sunny Florida and raced in cold Michigan.
Vehicle Modeling
With this wealth of tire data, I developed a tabular model of the car to iteratively transfer load and pick the optimal springs, rollbars, and suspension geometry to maximize lateral force and acceleration.
Vehicle Simulations
Once the geometry was locked in, the event specific setups were determined using the 7 DOF multibody model that became model used for my Master’s thesis.
Mechanical Design
Suspension Package
In order to maximize the space for the driver, I kept the suspension external to the chassis. We also minimized the components and package (lightest part is no part) by routing the stabilizer bar (green) through the chassis’ cross member. This kept the mount stiff while reducing mass. We also used a progressive motion ratio in order to help keep the aero devices stable.
Wheel Corner Package
This is the front corner cross section. The Rear has a similar style, but the spindle (pink) is larger to accommodate the spindle. Using this setup, we were able to remove mass, decreasing unspring weight and rotating inertia.
FEA and Optimization
For the more complex parts, topology optimization was used to design the parts to achieve either minimum mass or maximize their stiffness. After the optimization, parts were designed in CATIA then imported to Ansys for FEA analysis.
Manufacturing
Rear Knuckle
Due to timing and cost limitations, ended up needing to use a welded steel knuckle/upright. In order to make sure our hard point did not warp, we used a heavy assembly fixture. After normalization and heat treatment, we post machined the critical interfaces to insure desired performance.
Design for Assembly
In order to minimize warpage of the frame, I designed the suspension to use thread on mounts for the frame connection. These mounts allowed us to thread heavy steel plates to the frame during welding to prevent warp and hold the points rigid. We also used a mechanical interlock to allow us to remove the differential mount, allowing for easy access to the engine and oil system.
Composites
During Graduate School, I was a TA in the school’s composites lab. I assisted the professor with teaching undergraduate students about composites and layups. During this time, we also used the lab to perform the layups for the FSAE team, including our hollow wings, body, and the undertray for ER-03 (pictured).
Testing
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Weld strength testing for alternative light weight tubing diameters. We needed to prove we are just as strong as a traditional frame.
Tuning laps of ER-02. We used these sessions to test for thermal issues in the cooling system and get through infant mortality of components.
RR spindle after half shaft failure. Root cause was out of spec half shaft angles causing a tripod failure.