Northeastern Electric Racing: 2024 Chassis Design
In January 2023, I took on a larger responsibility within Northeastern Electric Racing: manging the 22A chassis project. As part of this new position, I am actively leading the chassis design for our 2024 competition car using SolidWorks. Since every other component is built off of the chassis, I have been considering the needs of all other projects in my design work. Feel free to read about my contributions below!
Inherited Design
Chassis Design - End of December 2022
Chassis 22A is a project that has been in development since June 2022. I took leadership over the project after the previous project lead stepped out of the role.
I had already made contributions to the chassis' design, mainly the addition of triangulated sidepods in October. I used SolidWorks weldments to add these features and apply the correct tubing sizes specified in the FSAE rulebook. These sidepods are designed to fit our batteries, and I discussed with the 22A Accumulator lead about sidepod geometry requirements.
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Before taking lead over the project, I was also involved in some general design discussions, such as determining suspension mounting points and designing the car to fit a 95th percentile male (PERCY).
Differential Adjustments + Understanding Design
I started reaching out to other systems within the team to meet their needs. I first met with the drivetrain team. The chassis design had a designated spot for our rear differential, but it didn't fit. I altered the design to ensure there was enough space for this necessary component using SolidWorks assemblies.
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Another one of my initial tasks was to familiarize myself with the design I was given. I had worked on the chassis design prior, but did not have knowledge about the rules or the necessary chassis components. I learned the rules surrounding the bulkhead, the two role hoops, and all of the bracing in between.
Chassis Assembly With Differential
Rules Compliance + Organization
I constantly check to make sure the chassis meets all competition rules. When combing through pages of rules, I found a handful of violations with the chassis design I was given and fixed them accordingly. This included moving braces closer to the tops of the two roll hoops, completing missing trriangulation, and adjusting cockpit size to fit driver templates. I balanced these fixes with our weight optimization goals.
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The SolidWorks part document I was given was also getting very cluttered, so I made a new revision from scratch. In this new file, I used reference planes to define the main structures of the car (bulkhead, roll hoops, rear) and used 3D sketches to fill the gaps. I organized all the frame members into feature folders with a proper naming structure. I also decided to add a feature folder full of sketches and planes used to check for rules compliance, such as sketches of the minimum cockpit profiles, minimum wheel base, driver profile, and more.
Snippit of Feature Tree Organizaiton Structure
Mid Design Review + Suspension Adjustments
I presented the chassis design in an official review to the entire engineering team for feedback. The feedback was overall positive, and mostly incuded minor changes to fulfill the needs of the team. However, the suspension team had significantly changed their design and required a significant change in their mounting geometry.
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This design change affected the entire chassis, including the sidepods housing the accumulators and the section housing the differential. I had be careful when rearanging the geometry so the accumulators and differential could still fit appropriately while still minimizing overall chassis weight. This is the curent stage in the chassis' design, and is close to final.
Pre-Mid Review Front View
Post-Mid Review Front View
Post - Mid Design Review & Evaluation
Post-Mid Review Design
One of the main goals for this project was a significant weight reduction. I made sure to optimize the geometry and use the minimum regulation tubing sizes. The current 22A design weighs about 80 lbs, which is a 25% weight reduction compared to our old chassis. Soon I am going to use SolidWorks simulations to conduct an FEA analysis on this design. Depending on this analysis, we may need to increase tubing thicknesses or add supports, but I do not expect a significant weight increase.
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Another strength of the 22A chassis is the consideration of subsystem integraton in its design. The last chassis did not consider the needs of the team to the same degree, forcing all the team to work around the chassis. Instead, I put a lot of effort into designing 22A for the team, and I included all subsystems in chassis design conversations.
I feel that I have done a great job accommodating the team's needs into my design, and I will keep this focus while finishing the chassis' development.
Force Simulations (Finite Element Analysis)
After addressing design changes prompted in the mid-review, analyzed the chassis with FEA. Using SolidWorks Simulations I tested the chassis for worst-case loading scenarios, including a 20g front impact.
In the front impact simulation, I chose to designate the rear bulhead as the fixed body because the rear bulkhead would deform the least in a catastrophic front crash.
Initially the chassis design did not survive the simulation and had a factor of safety of 0.87. I was able to identify weak points from the simulation, including a force concentration between two nearby nodes on the front roll hoop. I combined those two nodes and increased the thicknesses of weak members in the design to improve strength.
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While testing the simulations, I noticed the top members along the car's length recieved more stress than the bottom members. I oriented all diagonal triangulations in the car to strategically redirect force from the top members to the bottom members to better distribute the force and improve the chassis's strength.
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My final chassis design is able to withstand a 20g front impact and has a factor of safety of 1.2 with respect to its yield strength.
Initial 20g Front Impact Simulation
Final 20g Front Impact Simulation
Final Design Review & Evaluation
Post-Final Review Design
I led a second intense design review for the chassis with about 30 - 40 participating engineering students.
From this review, We developed a short list of action items, the main tasks being to decrease the factor of safety from 1.5 to 1.2 and to double check that the chassis has enough space for key components such as the safety light up top.
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After addressing the action items I was able to lock the design. The final chassis weighs 83 lbs, which is more than a 20% weight reduction when compared to the previous chassis. This chassis was also designed with care and consideration for all subsystem projects. This chassis design also survives all of our worst-case simulations, incuding a 20g front impact.
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Overall, I would say this chassis design is a huge success and a great improvement over our last chassis. I am proud of my significant contributions to the chassis design, and feel I have greatly developed my ability to work cross-functionally through this project.
Relevant Skills
SolidWorks Simulations
Used to ensure chassis design can survive a 20g impact and other load scenarios with no plastic deformation
SolidWorks Weldments
Used custom weldment profiles to create all chassis members
SolidWorks PDM
Used to share chassis files with the entire team and reference other project designs
SolidWorks Assemblies
Used to interface other project designs with the chassis for proper component integration