In what way is carbon fiber used to reduce impact force?

[u/scrambled_turtle]

If I’m not mistaken, I believe you can layer carbon fiber in a way that can control how it bends and flexes under load. An example of this would be how the 2021 Mercedes’ rear wing “leaned” backwards at high speed and McLaren’s DRS flap in Baku. Is there resistance curve that increases as you get deeper into the crash structures?

Also, the Boeing 787 Dreamliner is made mostly of composite materials. A carbon reinforced plastic fuselage is created by a machine that automatically lays down the material instead of a trained engineer doing it by hand. Do F1 teams use this technology or are their parts too intricate/small to benefit from an automated system?

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[u/ledzep4pm]

I did my masters thesis about 10 years ago in composite crash structures.

Basically, it takes energy to break things.

In a road car you have a crumple zone, steel is ductile and folds up a bit like an accordion bending the steel like that absorbs/dissipates energy.

A composite like CFRP dissipates the energy in different ways. A tubular crash structure makes a kind of mushroom shape when crushed, this can occur on both the inside and outside of the tube and are called fronds. While this happens the fracturing of the matrix and fibres displayed a log of energy, a lot of energy can be dissipated through friction between the fronds and concrete too.

The challenge with these structures is that the specific energy absorption of some of these materials is very high, while they means you can absorb a lot of energy in a lightweight structure you have to balance the stiffness of the structure against the amount of material used. Buckling is a big issue as if it buckles it won’t absorb any energy, you can thicken your structure, but that can make your deceleration too high. The tube shapes used in the side impact structures are good for this, but something like the nose which has to have a complex outer shape is trickier. You can include honeycomb cores, to stiffen it but that will also reduce the specific energy absorption by about 50%.

[u/Low-Somewhere-5913 → u/[deleted]]

AFP is used in F1.

[u/Low-Somewhere-5913 → u/[deleted]]

I'm not at liberty to say 🙃

[u/Low-Somewhere-5913 → u/[deleted]]

AFP is definitely used in winding scenarios for irregular fibre placements that winding can't achieve, i.e., knuckle reinforcements. Winding itself shouldn't be thought of as AFP.

[u/PestoCalabrese]

It takes energy to destroy stuff, each chemical bond that breaks takes away energy from the impact. There are a lot of chemical bonds in a carbon fiber crash structure.

[u/Low-Somewhere-5913]

Cfrp has a very high specific energy absorption in comparison to metallics. There's a lot of engineering in the geometry of crash structures in order to control and initiate the collapse. The high SEA value is the benefit you're looking for here

[u/loud_v8_noises]

F1 teams likely don’t use AFP (automated fiber placement) similar to aerospace because the structures they’re building are not in production where hundreds or thousands of units are being built and the structures are much thinner than say a fuselage or wing structure.

That said the carbon fiber materials are essentially the same between F1 and aerospace. They’re just hand placed instead of machine placed during layup.

Also, you will still find a lot of hand placed composites in aerospace today even.