Skip to end of metadata
Go to start of metadata

You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 2 Next »

Circular Tube vs. Square

  • Round tubing is stiffer in torsion while square provides a stiffer beam 
  • Square tubing is easier to fabricate (no ‘fishmouth’ joints) but the tube distorts under load by ‘lozenging’ or ‘panting’.This adds to compliance and may lead to fatigue cracking.
  • Round tubing is best option, and does not need as much design justification. Harder to manufacture, but will lead to less design and strength issues 
  • May want to consider square tubing for horizontal frame members to simplify suspension mounting points and makes cutting planar joints easier
  • Triangulation/reinforcement in square tubing can greatly improve structural integrity

Design Notes:

  • To improve manufacturability: design chassis to be "self-jigging"
    • Constructed in separate parts which are then joined together

Choosing a Grade of Steel

Summary: Comes down to weight savings vs. cost and manufacturability. Chromoly provides more weight savings, but is more expensive and harder to fabricate 


4130 ChromolyCold Drawn Mild Steel (1018)
Weldability
  • Recommended to use TIG welding or nickel bronze welding (brazing)
  • Requires pre and post weld heat treatment to normalize the structure after any weld, or becomes very prone to fracturing
  • Can be problematic doing small attachments (brackets + other modifications) on the fly since every weld needs to be heat treated afterwards
  • Recommended to be welded professionally
  • Recommended to be TIG or nickel bronze welded, but MIG works as well
  • No heat treatment necessary post-welding
UTS (Ultimate Tensile Strength)
  • 590 MPA
  • 420 MPA
Elastic Modulus
  • Same
  • Same
Positives
  • Can use thinner walled sections in areas due to higher strength
  • Better strength to weight ratio
  • Less likely to be dented; higher structural integrity
  • Less expensive (by 50% approximately)
  • Easier to weld (more options) and no pre or post welding necessary
  • Better to use with a lack of welding experience
Other Teams
  • Principia

ASC Regulations

  • Battery enclosure must be secured to the chassis
  • Array needs to be attached to chassis with braided steel cable 
  • Safety belts need to be attached to chassis 
  • Needs to be designed to accommodate a minimum 5g load from all directions
  • Crush zone attached to the chassis on sides of the driver
  • Variety of other roll cage requirements

Welding Process

Welding at UW

Important Notes from Other Student Teams

Good Resources

  • No labels