Category: FSAE Electric

Introduction

For my first season on an FSAE team, I was able to contribute as a chassis engineer. During that season, my subteam and I defined our engineering needs, made design choices accordingly, and successfully manufactured and validated our design through real-world testing.

Need Statement

“A readily adaptable, cost-effective chassis that will optimize rigidity and weight.”

High-Level Design Choices

For the vehicle chassis, a few defining decisions had to be made at the beginning of the design cycle. These choices included the configuration and material.

Configuration: Spaceframe

Material: 4130 Chromoly Steel

Torsional Rigidity

As seen in the plot, there is a point of marginal returns where it is not necessary to increase the chassis stiffness further. This occurs around 90% of full vehicle stiffness or 1960 lb*ft/deg chassis stiffness, which was chosen as our rigidity goal.

Manufacturing and Validation

Welding Jig.

Simulation Validation

Physical testing gave a torsional rigidity of 2307 ft*lb/deg, representing only a 2% error from the simulation’s prediction.

Outcomes

Although this frame did become somewhat heavy from the extra frame members required to house the team’s dual-battery system, it was extraordinarily rigid which allowed the suspension team to precisely tune their setup. As well, its ability to accommodate this unique battery was rewarded by the design judges; helping the car place in the top third of teams in the design event in TAMU’s first year competing in this category.

Learnings

With this being my first major collegiate design project, it is nearly impossible to summarize the amount of hands-on engineering knowledge I gained from this experience. Beyond all the engineering drawings, fastener types, and manufacturing processes, I learned something much deeper from this design: how to manage an engineering project in the real world. With no rubric or answer key to fall back on, me and my team had to decide what the best answers were for ourselves and be confident enough to follow through with them.

Introduction

Like many racing series, the Formula SAE competition requires safety equipment for drivers to race. I was responsible for a few safety systems on our car, specifically the impact attenuator, firewall, and head restraint.

Impact attenuator

For the impact attenuator, I had the option of making a custom device or using one of the two standard attenuators. Because a custom attenuator demands extra testing time and budget while offering nearly no performance benefit, a standard attenuator was the obvious choice.

Between the two standard attenuators shown above, the honeycomb aluminum design was chosen over foam because of its smaller footprint, allowing the Aero team more space to design their nosecone.

Firewall

For the design of the structure, I utilized the Solidworks sheet metal tool, adding bends to avoid interference with the chassis. To attach the firewall, riv-nuts were used in the spots where the firewall would need to be removed and installed frequently to ease this process.

The final product was fabricated from a dual-layer system of aluminum and Nomex 410 paper.

Head Restraint

The final safety system I oversaw was the driver head restraint. It is required by rules that the mounting of this device is capable of sustaining 900N of rearward load and 300N of shear load.

For the construction of the headrest itself, I utilized HPDE backing, Confor Impact foam, and a vinyl cover. To assemble the final product, I was able to reach out to a previous team member to do all upholstery work free of charge.

Outcome

Each system obtained approval from the inspectors, making our car the first TAMU FSAE EV to pass the rigorous tech inspection.

Learnings

While the designs were primarily rules-defined, it was an enjoyable experience to explore how to adhere to those rules while creating lightweight and user-friendly products. This is a skill I could use in industry, where many designs have to be effective while following some set of rules or codes.