Header photo by Patrick Ooms
Today is Wisdom Wednesday! The day where we enlighten you a little more on the technical aspects of our project and how we challenge the future of sustainable mobility with these technological innovations. Structural designer Andreas will explain everything about carbon fibre and core materials.
Strong but light
For our car, we mostly use carbon fibre. Firstly because the material is very light weight and secondly, because it is very strong and stiff. However, this is only true in the direction of the fibres. A single sheet of carbon fibre can bend out of plane rather easily. To prevent the bending of the carbon plate you need to increase the thickness of the laminate.
One option is to use multiple layers of carbon in different directions. A big disadvantage of this option is that this quickly adds up weight. Another solution is to use a lightweight foam-like core material. The core material increases the height of the laminate drastically without adding much weight. The stiffness of the construction is increased a lot because of the height. Adding a core material is a very effective method, because the stiffness of the construction increases a lot, while the weight doesn’t increase that much! The core itself basically just hold the two sheets of carbon far apart. It doesn’t take much of the force. That is mostly done by the much stronger sheets of carbon on the outside.
Geometry is key!
Stiffness is important in a solar car. You want the car to stay in the shape it was designed in, because of the aerodynamics of the car and, of course, the safety of the driver. Parts that are curved in two directions are stiff due to their geometry, so these tend not to have a core material. So as a rule of thumb all the flat parts in the car are strengthened by core material. If you look closely you can see the core material in the outer shell stop where the curvature begins.
In the video below, Sam, team member of last edition, shows the differences between layers of carbon fibre with and without core material in between.
Wisdom Wednesday recap
- A great part of the car consist of carbon fibre, because this material is very lightweight
- Carbon is stiff and strong, but only in one direction. Which is why we use core material to make our construction stiff and strong in more directions
- Some parts of the car, we don’t use core material. The construction is in this case strong enough by geometry