The chassis is essentially the backbone of the car. All components and loads must be attached to the chassis. Chassis design also affects the overall look and feel of the car as it is typically the first thing to be noticed. We currently use a carbon-fiber and steel tubing half-half chassis.
What We Do
This subsystem is tasked to design, develop, build and validate the chassis of the car. In order for a racing chassis to be effective, it must balance structural rigidity with a lightweight and aerodynamically efficient design. We do a significant amount of CAD design, analysis, and physical validation to ensure this outcome. We also work closely with other systems, such as suspension and powertrain, to accommodate and create any applicable mounting or packaging needs.
Since the beginning of GTMS, our chassis have always been comprised of a steel tubing space frame. The first year for a composite chassis design was 2017, which effectively lessened the weight of the car by approximately 7 pounds. Since the team did not compete in Michigan last year, we were unable to ascertain to what extent this would impact the car’s performance. While time restrictions prevented in-depth physical validation, this upcoming competition year will provide the opportunity to develop this influential change in the car’s design and further promote weight reduction.
Chassis design must take into account desired stiffness, structural strength, center of gravity, weight, manufacturability, and ergonomics. The book, Design of a Formula Student Racecar Chassis, has great in-depth information on these components, along with material specifications and benefits.
Currently the car’s chassis is comprised of ⅔ composite “monocoque” and ⅓ steel tube space frame. The two are manufactured separately and mated together. We make the steel chassis in-house. All tubes are welded together, and the frame is typically shipped out for powder-coating.
The monocoque requires several phases of composite work. A plug in the shape of the desired design is machined, sanded, and prepared to lay-up the mold for the monocoque. Once the mold has cured, the monocoque itself is laid-up based on a predetermined ply schedule, which is designed to maximize the strength of the chassis by offsetting weave patterns, thereby preventing shearing. It is a carbon sandwich structure, with about 7 layers of carbon on the inside and outside, and aluminum Flex-Core in the middle. The monocoque is completed with the help of Delta Tech-Ops, the airline’s facility at the Atlanta airport, as we use their autoclave for our composite work.
Future Goals and Projects
There are several goals for chassis, both short and long-term. Currently, we are planning to use the same molds for the F2018 car, limiting our choices in terms of design changes. These currently include: different ply schedules, core thickness and materials, re-engineered hard points. We have more freedom on the rear chassis. One notable improvement goal is the triangulation points, especially on the rear suspension pickups.
For long-term goals, we are looking to improve the geometry of the monocoque, lower the nose to lower the CG (center of gravity) height and give the driver better visibility. Our ultimate goal is, of course, to complete a full monocoque.