Current TRL: 5 (11/14/21)

“The new design of the chassis side pods has been created.”

Chassis

 

(2021-2022 Team’s Chassis)

    The Chassis team is responsible for helping every single subsystem achieve rules-compliant mounting solutions for their components, as well as provide a sufficient torsional stiffness to help with the overall performance of the vehicle. Due to the fact that the chassis is a space frame design we can create iterations upon the current frame design as to always maintain rules compliance and improve functionality.

Literature Review

At the base of any good racecar’s design is a good chassis, the chassis is the core of the car and is a crucial part of the design of a good car. Because the chassis is where all the subsystems come together, it is imperative that the chassis design is solid. Naturally, when designing the chassis, you are going to want to make sure that it is the best that it can be.

Full Literature Review

Broader Impacts

Good chassis design is more than just for racing applications, one of the main reasons good chassis design is so important is for the health, safety and welfare of those in the vehicle. The better the chassis is, the better it will be at protecting those within it. Even on a global scale, good chassis design is important no matter where and what is being driven. Weather it be for a rally car that might have to protect against rolling, or for a mother wanting to protect her kids in a car accident, or even for a food cart in a bustling city, a good chassis is important no matter the social, cultural or economic setting. Now with climate change and  resources becoming scares, there are significant environmental impacts as well. Chassis design now needs to be energy efficient and use less materials than in the past, keeping the well being of the environment as a priority.

Problem and Goals

After examination of the chassis, along with help from competition judges, we found three main problems that needed to be addressed. First was the missing side impact structure, next was the side pods needed to be redesigned, and that the rear subframe needs to have improved triangulation. The first goal was to determine if the design from the previous years team for the side impact structure was good. Next was to develop a design for the side pods that will allow the battery pack to have easy installation. The last goal was to  create triangulation for the rear frame with guidance from a SES chassis inspector.

Metrics Constraints and Objectives 

When looking at how we need to go about achieving the goals that we set for ourselves, we had certain constraints limiting what we were allowed to do. We used the 2022 Formula Hybrid Rules as well as the AMSE V V 10 standards to inform our design decisions. With our rules set in front of us, we determined our objectives to be the assessment of the side impact structure deign, the development of a new side pod design that incorporates a simple mounting design for the battery packs, and the design of rear triangulation around the drive train. With this in mind, we needed to determine how we are going to measure the “goodness” of our designs. For the chassis, those metrics are weight and torsional stiffness, which is a measure of how much the chassis flexes under load. A lighter chassis better in helping the power to weight ratio, and a stiffer chassis is better as it improves overall drivability.

Design Proposal

With ideas gathered from the problem space, we have designed a new side pod structure that will allow the battery packs to simply be installed/removed as needed. When creating the new side pods we had the design goals of increasing the chassis’ torsional stiffness and of making it light weight. However, this was not our only goal. We also have goals set to test the new design by seeing how it affects the torsional stiffness of the overall chassis. We plan on doing this using finite element analysis (FEA) and a physical test rig. This leads us to our goal for the second semester, which is to design a rig that can test the chassis’ torsional stiffness. When designing the test rig we will have a few design goals in mind, those being simplicity, adaptability to accommodate future chassis designs, and the ability to deconstruct the rig so that it does not compromise needed space in the shop. The design of the test rig will be completed early second semester, this way the chassis team can then shift its goal to designing a new chassis for future teams.

Codes and Standards

Standard for Verification and Validation in Computational Solid Mechanics (Link here)

The standards linked above are based on verification and validation of solid mechanics, this can be applied in the testing of the chassis design.

Mechanical Documentation

2020-2021 Chassis Team:

  • Finalized the new rear frame, here is a zip of the most recent version (003) Link to zip file hosted in Google Drive  =  Released Nov. 9, 2020

2021-2022 Chassis Team:

  • Finalized the new side pod design, here is a link of the most recent versions (SidePodFinal_L and SidePodFinal_R) Link to assembly files hosted in Google Drive  =  Released Oct. 31, 2021
  • Finalized the new frame assembly with the new side pods and tested for torsional stiffness. Link to full frame assembly file (FullFrameNew) and simulation results (New Chassis FEA Simulation 1) hosted in Google Drive  =  Released Nov. 14, 2021

Budget

The only resource that the chassis team needs is steel in different forms. This includes tubes, both circular and square, sheets, and angles. The exact cost of the materials will not be known until the design of the test rig is completed. Regardless, the chassis team will require no more than $1000 in materials. All other costs are associated with welding and its resources, which will be provided by the college.

Link to the Chassis’ complete Bill of Materials on Google Drive (2020-2021 Team)

Components:

  • Side Impact Structure
    • Support on the side of the chassis acts as a protective barrier for the driver, also adding structural support to the chassis.
  • Side Pods
    • Component on the side of the car just outside of the side impact structure. The main purpose of the side pods is to safely secure the battery packs on the car.
  • Front and Main Hoops
    • The front and main hoops are located in front and behind the driver, they act as protection against rolling.
  • Impact Attenuator
    • The impact attenuator is what will absorb energy in a crash, acting as a sort of cushion in the event of an accident. It has been tested and is up to code for competition.  
  • Frame
    • The frame of the overall car is the most curtail part of the entire build. Thankfully it is rules compliant for the most part (excluding the side impact structure) and has been verified with the current rule book.

First Semester Accomplishments

We confirmed that the design for the side impact structure is rules compliant and have the parts ready to be manufactured. As for the new side pod designs, we have completed a design, implemented it on Autodesk Inventor 2022 to find the weight and test for torsional stiffness. We had to sacrifice a little weight in order to increase torsional stiffness while meeting our other design goals. And with feedback from one of the structural equivalency judges, we developed triangulation on the rear frame and have the parts ready to be manufactured.

Chassis TRL Chart

TRL What does this look like? Expected Completion Date
9 Perform physical tests on the static car 03/29/22
8 Design and fabricate physical tests rig 03/15/22
7 Complete Chassis Assemble 02/01/22
6 Fabricate new Design 12/07/21
5 Test new side-pod design using FEA 11/09/21
4 Formulate new side-pod design 10/27/21
3 Formulate a plan to address issues 9/29/21
2 Address issues and non-compliant areas 9/21/22
1 Chassis is in the shop Completed

Meet the Team

Will Huffenus – Team Head, Design Lead

Midyear Chassis Development Poster (here)