Between January 2020 to October 2020, there was a major change in vehicle design that involved removing the structural bottom panel from the design. A major premise of MS14 was that we would be able to manufacture a structural bottom panel which would provide us significant weight reduction and maximize occupant space. Major factors that prevented us from having a structural bottom panel included the absence of a sponsor for an autoclave, the aggressive bend angles of the bottom panel that were difficult for honeycomb nomex core to conform to and the general difficulties of performing prepreg carbon fiber manufacturing.

Figure 1: Image of the Bottom Panel CAD

What needs to be now completed is a vehicle re-design that does not consist of a structural bottom panel while satisfying all American Solar Challenge Regulations (ASC Regs).

Below are images from ASC 2021 Regs Release A that relate to the structural design of the vehicle. There are possibly even more regulations that can be relevant factors for vehicle design. It is strongly recommended to fully review the latest release of the ASC Regs before beginning any design project. Feel free to add screenshots of additional regulations that may apply.

• Minimize weight
• Minimize labour
• Minimize composites manufacturing
• Lean towards metal solutions because of:
• manufacturability, time, complexity/simplicity, cheaper, faster, easier
• Lean away from composite solutions
• composite simulation has complexities and unknowns
• but having composite panels in simulations generally yields better simulation results
• Make solutions as simple as possible; helps in the long run
• manufacturing, number of people needed, resource limited, minimize cost, minimize lead times

• Vehicle weight that we use to design is 720 kg.
• Would want to get a more updated quantity of how much the current assembly weighs.
  Would need to include at least: Chassis tubes, Dynamics assembly, Battery Box, Seats, and more.
• Can work from a baseline how much the Chassis weighs and then see how any further modification creates how much percentage weight change
• Should do onsite measurements and inspection of any implementation method before finalization. This is because there are inaccuracies with the welded Chassis assembly.
• We will not model the current thin Bottom Panel and put it into simulations in hopes of contributing to structural integrity
• There are too many inconsistencies on the physical bottom panel, e.g. too many wrinkles and unevenly distributed patches of carbon fiber
• There were also too many issues with manufacturing it therefore it should not be considered at all
• It is also not within our scope or capacity to model a half built bottom panel
• We will not manufacture another bottom panel using the current mold
• Too expensive; not worth the time; largely backed by Jason and Matt (Mech Advisors)
•  

• Review previous simulations
• Consider reviewing MS12 simulation files and documentation to learn more about what setups and assumptions that they used
• Reviewing simulation setup
• It is optimal to be completely certain that our simulations are producing accurate results. If simulations can produce safe results, then no additional weight or labour is added to the Chassis.
• Jason and Tommy are available to review FEA setups depending on their availability.
• Adding chassis tubes, e.g. more tubes, thicker walled tubes, larger cross section tubes
• Previous simulations were done by Tommy Tran during W2021 term to see how adding tubes can help with passing vehicle collision requirements. Adding a total of 29 tubes did not yield an impactful result (some stresses remained over 1000 MPa). This is assuming that FEA simulations were setup correctly (has yet to be fully verified - May 3rd, 2021).
• Source: Chassis Simulations for 2021-03-21 Chassis Reinforcements - Mechanical - Confluence (atlassian.net)
• Sheet metal across a plane of tubes
• Carbon fiber panel has better strength-to-weight ratio
• Sheet metal is easy to implement using welding or fasteners
• Sheet metal versus carbon fiber panels is balancing between
• weight + cost vs effort (have to make the carbon fiber panels) + reliability
• Carbon fiber panels across a plane of tubes
• Very good strength-to-weight ratio
• Involves more manufacturing and time. It also has to be manufactured properly to be effective.
• Do we make any CF panels accurately? Have we performed destructive testing on CF panels yet?
• Not yet. Would need to be completed within Material Testing Project which is led by Tommy Tran
• Would likely need to add some tubes to provide good adhering surfaces
• Try to use carbon fiber panels to replicate the benefits that the structural Bottom Panel was intended to provide (i.e. distribute load across all tubes to mitigate point leads; contributes to overall stiffness of the car)
• Reinforcing joints
• add gussets
• add tubes to triangulate the corner
• Reinforce tubes
• increase tube cross section
• increase tube wall thickness

Please document your work in a confluence page for any work completed for Midnight Sun.
For this specific project, it would be highly advised your documentation includes the following information:

• Directly Responsible Individual (DRI)
• Advisor or Reviewer
• Dependencies
• Location of work files, e.g. simulation files.
  Include file name and folder path.
• Date
• Child pages to separate and document sections of your work

Last updated: May 6, 2021

Legend:

• Red = High Priority

• Purple = Medium Priority

• Yellow = Low Priority

Comments:

• Timeline - depends on school and work term report

• Sounds like we are on decent ground; not the ideal case, but ok

• Likely that we will need a third week

• Mechanical Advisors
• Jason Hekevin buiMatt SuskiTommy Tran
• University Professor on Composites
• John Montesano | Mechanical and Mechatronics Engineering | University of Waterloo (uwaterloo.ca)
• Can help with understanding what failure modes to look out for
• What failure values to go by for Ansys ACP Post (composite failure analysis)
• Learning about full Chassis vehicle design would not be too beneficial or relevant at this point
• Resources to triangulate a frame to improve loading
• very sparse amount of resources online
• there is also no accurate solution method that is recommended for all scenarios
• FSAE papers for inspiration on vehicle design
• some hybrids, some purely tubes, some purely composite except for roll cage
• seeing how they do certain things can bring inspiration
• Note: all vehicles have their own loading conditions and properties so it is tough to make a Chassis frame that optimizes all scenarios and what other solar car teams do may not be applicable/feasible for our vehicle.