Aero-Chassis Integration Project Debrief and Meeting Notes

Owned by Tommy Tran
Jun 20, 2020
4 min read

Criteria

  • ASC2020 Regulations - Section 10.1 Body Panels

    • All body panels and arrays must be securely fastened to prevent unintended movement

    • All moving parts must be suitably covered to prevent accidental human contact when solar car is fully assembled

    • Interference or rubbing of the wheels with the solar car’s body, wheel well, or structure at full steering lock or suspension travel is not permitted.

  • MSXII Internal Requirements

    • Panels should not be able to come loose due to vibrations under any circumstances

    • Fastening system must be able to be release from the exterior of the car

    • Fastening system should be streamline to reduce any aerodynamic interference and turbulence

      • Streamline: make object free from turbulence

    • o   One unit of the system (i.e. both the aerobody and space from components) should weigh less than 100g

    • Must take less than 30 seconds to release the fastening mechanism

    • Releasing the fastening mechanism must use at most a single tool

  • MSXII Soft Requirements

    • Ease of manufacturing

    • Weight

    • Costs (material, method of manufacturing, etc.)

Project Debrief / Meeting Notes

  • Bottom panel – the tubes attached to it are square tubes

  • Catamaran – touching tubes are square tubes

  • Can assume all tubes are square

  • Long round tubes are not attached

  • Horizontal tubes are not attached

  • Side panels need to be glued to the long round tubes at the top

  • Can assume bulkheads are glued to square tubes

  • Roof and trunk are not glued to the chassis because they must be detached

  • Bridges are undecided – glued to side panels or top tube

  • Will have Matt sit in on an early stage (considering our options) then another during a design review

  • Adam’s thought –

    • universally, adhesives have a higher strength in shear than in tension –

    • A carbon fibre layer, core, top CF layer – what will the side edges look like.

      • The outer edges of the bottom panel (the buckets), what will it look like on the side. Will it be exposed CF layer, exposed core, exposed CF layer?

      • Adhere chassis to the side of it?

    • Square chassis tubes are adhering on the top of the bottom panel – loaded in tension

    • Would it be feasible to include chassis tabs that extend downwards so that we can apply adhesives to the chassis tabs on the side

      • Make a cutout on the bottom panel on the inside or outside?

      • Dump adhesion to the exposed portions and lather on resin across exposed cross sections to increase strength

      • The Benefit: That surface will be loaded in shear which will increase the adhesion between the chassis and bottom panel

      • How feasible is this in manufacturing??? Making cutouts in the bottom panel

  • The adhesion between the catamaran and the chassis

  • If we can adhere the bottom panel to any tubes that trace the catamaran side – huge significant increase in strength

    • More tubes might be added for the battery box to set on the catamaran more effectively.

  • Might need 3d print or machine a small scale

    • Catamaran sides to chassis tubes – gluing a curved surface and a flat tube together – might need adapting parts

  • Hand Calc to shutdown ideas

  • Weight of 4 people in a 2g bump can be taken care of by adhesion in tension

  • See what tensile strength is required – base our research on that

  • Will simplify things by removing the need to do fancy things to adhere things in shear (essentially stop us from doing more work than necessary)

  • Bulkheads connects the chassis to the catamaran – with background that the bottom panel is structural – will bulkheads still need to be structural? – I think we do to keep people safe during rollover

    • Loading supported by the bulkheads is transferred onto the new chassis tubes added

      • Question given to the person doing the current simulations

    • Is having less structural parts better or worse

      • Less means we need less adhesive choice for different requirements/design for less structural parts

    • If bulkheads are structural, then it would make the catamaran serve as ribs to increase (shear loaded) adhesion

  • If bulkheads aren’t structural, then you can make the cutout you want and have an easier adhesion process

  • Bulkhead lies on a lot of backing chassis tubes (features), all these features increasing things that are loaded in shear

    • Replaces the need to add more chassis

  • What does it mean to be structural?

    • Panels that are load bearing – expect to transfer load

      • E.g. roof breaks during rollover, the car will keep operating

      • Will the part be destroyed?

  • What to do about round tubes?

  • How to adhere panel to panel?

  • How will aerobody panels be attached to chassis?

  • Roof is not glued down

  • Side panels would be glued down to the chassis tubes

    • There should be an external flange or bridges

  • The roof and side panel wont be sufficed using just the flange

    • A bridge will be used instead to overcome this gap.

    • Bridge gets glued onto the chassis tube

    • Bridge would be made out of carbon fibre

  • Bridges CAD are to be made right now.

    • Need to have models before we bring in Matt

  • Come in with challenges we are looking to tackle

  • Adhere the sidepanel to the chassis, roof to the chassis, then use the next meeting to look at the options I came up with. 

  • HMW:

    • Look into options for adhesives

    • What do other cars use

    • Later on we can do calculations in order to evaluate our options

  • Adhesives:

    • Selecting adhesive

    • Designing features to adhere one thing to another

    • How to adhere CF to chassis and CF to CF

  • Kevin’s involvement:

    • No CAD; there is none in this project

    • Advising, sitting in on meetings

    • Discussions about design

Additional Slack Discussions with Kevin:

  • Going forward with worst case scenario of calculating the adhesion between the bottom panel and the chassis. This assumes the main attachment is between the buckets and the bottom chassis tubes and bulkhead B with all forces in tension

  • We should only care to consider load bearing aerobody panels when speccing the strength of the adhesive; a panel that doesn’t bear any load would only need an adhesive strong enough to hold itself together and not collapse due to leaning or wind. Loading bearing parts have a much larger loading condition