Do the carbon fibers of F1 racing cars have good impact resistance?

The carbon fiber reinforced composites, in fact, use a lot of carbon fibers, arranged in a certain direction, and then closely linked with resin or other bonding materials. As shown in the figure below, each cylinder is a carbon fiber, which is filled with resin filled in the middle. The distribution density of these fibers directly affects the final material properties. Because of this, we can control the final performance of carbon fibers by adjusting the so-called fiber volume fraction, which is the fiber volume ratio. Simply put, the denser the fibers are, the more fibers in the unit volume, the higher the strength along the direction of the fibers; conversely, the thinner the fibers are, the fewer fibers in the unit volume, and the lower the strength of the final carbon fibers.

For the carbon fibers used in engineering, the arrangement of the fibers can be either single-directional or multi-directional overlapping. Of course, the most commonly used is multi-directional crossover, which is the appearance of our common carbon fibers.

For example, this is a single direction.

 

This is a multi-directional cross, and the appearance of our common carbon fibers is this two-way cross texture. This is the case with the original carbon fibers, which are actually more like cloth, which can be bent and rolled into a roll.

Carbon fiber is much less dense than steel, aluminum alloy and other metal materials, that is to say, to make the same parts, almost volume, to meet similar mechanical properties, carbon fiber parts are much lighter than metal parts, which is very important for racing.

This has led to another misunderstanding of carbon fibers, that is, carbon fibers are a super material, so everything made of carbon fibers must be far stronger than that made of metal. In fact, engineering design is a synthesis of materials and sizes, not just depending on materials.

The chassis and body of F1 racing car is not a simple single layer of carbon fiber, but a sandwich structure with two layers of carbon fiber material, the middle of which is a honeycomb structure made of aluminium alloy or other fiber composite materials. Carbon fibers on the upper and lower surfaces are usually composed of multi-layer carbon fibers, each of which is the kind of carbon fibre fabric mentioned above when we say that there are many directions crossing. The stiffness of the whole system can be adjusted by changing the height of the intermediate honeycomb. Because these honeycombs are hexagonal hollow structures, they are actually very light in weight. Honda fleet tests showed that compared with pure carbon fibers without intermediate honeycomb aluminium alloy, the addition of aluminium alloy honeycombs with a thickness of 3 times that of carbon fibers increased the weight by 6%, but the stiffness changed to 37 times that of the original. At the same time, the deformation and fracture of these aluminum honeycombs can absorb a lot of impact energy when the accident happens. It’s like putting a lot of pop cans in close proximity. You have to crush these pop cans before you can reach the inner carbon fibers.