Carbon Fiber Rim Design

Owned by Hamza Abuabah
Last updated: Jul 13, 2019

The wheels of the MSXII were heavy, overbuilt, and kind of ugly. They were also difficult to manufacture since they required high-precision machining. However, it is not nearly difficult enough, and created too little of a mess, not to mention, it was too predictable.To fill in this void and bring chaos back into Midnight Sun, composite rims are being developed for MSXIV. 

The MSXIV was modeled with aerodynamics in mind from the very start of the design process. The aerobody went through hundreds of iterations and simulations to perfect the airflow around it. However, these designs were build with the assumption that the wheel will not have spokes, since spokes, like miniature blenders, tend to create vortices and ruin a lot of the work put into fixing the aerodynamics of the car. If that wasn't enough, metallic spokes are quite heavy compared to composite ones. Carbon fiber wheels are the most popular for their great strengh-to-weight ration and aesthetic appeal. They have been used on many solar cars before, even being mass-manufactured by small companies such as Nomura Co. (https://www.facebook.com/NomuraCo/posts/16inch-carbon-fiber-wheel-2nd-batchdispatch-to-teams/1983506268560368/) and GHCraft (http://www.ghcraft.com/shops/cfw/cfw_16c_e.htm) exclusively for solar car teams . Some rims have been noted to decrease drag by ~5% and rotation inertia by 25%. These numbers will be used as part of the requirements for this project


Rim Simulations in ANSYS ACP

Oh god, don't even get me started.


Composites Testing




  1. Tensile test
  2. Compression test
  3. Flexural strength testing
  4. Testing void content

Composite properties derrived from tests above depend on the quality of the composite layup. One of the most important parameters to measure the quality of the composite part is void content. The density of the voids in the composite can affect many properties of the composite, especially the transverse properties of a unidirectional composite. This void content can be used as a score of how well the layup turned out, and different manufacturing methods can be compared. Void content should be kept below 1% for a good composite, and it is discouraged to use composites with a void content of >5% for critical applications. This number can be measured by following ASTM standard D2734-16, attached to this page.

ASTM D2734-94

Rim Specific tests

  1. Pressure testing
  2. Buckling testing
  3. Environmental testing
  4. T-Joint testing







Sources:

The Winning Solar Car.pdf

(I'll add more later I need to sleep soon)