How will cars be different (materials used)

In My Humble Opinion
1

It seems clear that how cars are built has been changing, and that this change is likely to accelerate. Where in the past cars were basically about a ton or two of steel with a little aluminum, plastic, copper, and maybe a smidge of leather, some cars now have large batteries, are made of alum etc.

So what is the most likely makeup of cars built 5-10 years from now? Predominantly electric, and so have batteries? Carbon fiber or alum or back to steel? What “new” materials will make up a much larger part than now, and maybe change their international trade?
Or maybe not much change at all?

2

The problem is money. Carbon fibre is great, but noting beats steel for simplicity of construction. Plus it is good for durability in structure and mechanical parts. A typical automobile application today needs some pretty rugged parts. Where less durable lighter parts may be useful would be in say, a small runabout restricted to lower speed city use. Unfortunately, licensing and insurance rules currently conspire (as does garage space and cost) to severely limit the number of people who would buy a more limited urban runabout as well as a full auto. And until self-driving cars come along, taxis and Ubers still need to be more than small 2-person vehicles.

An interesting take is the Pontiac Fiero - it was basically a metal frame with plastic pads inserted in holes in the frame. A fancy machine would then mill and drill each pad so the holes lined up perfectly to allow plastic body panels to attach. Not sure what the issue would be why this was not a successful option.

The Tesla battery is interesting - you can find videos analyzing it on YouTube. It is assembled from thousands of batteries that look like AA cells. Extreme temperature is a problem for battery life, so the whole assembly is bathed in coolant and there is a small radiator to maintain temperature levels. However, since the amount of heat is much much less than some contraption that burns hydrocarbons, there are less issues with the coolant system than with a gasoline auto. But, this does make simply exchanging batteries a bit more complex; which is why they use high-speed charging instead.

Despite good ideas(?) over the years, I have not heard of a viable alternative to inflatable rubber tires.

Self-driving? Nice idea in ideal conditions, but needs a LOTof work before we take the steering wheel out of the car.

3

Five to ten years isn’t all that that much time in terms of modern automobile companies’ cycle plans.

What you’ll see in five to ten years is steel. It’s getting stronger, which means we can use less of it, making it effectively lighter.

You’ll see more aluminum, from closures panels (liftgates, doors), to entire bodies (F-Series, Expedition).

You’ll see some more composites, mostly for closures panels, but only used selectively due to cost.

You might start to see build options, say, the ability to choose steel, aluminum, or carbon fiber for your roof, each of which brings in a nice premium for the company.

Battery packs are increasingly structural, but the battery cells themselves aren’t structural. They’re heavy, and so by weight, you’ll see a higher contribution of cobalt, nickel, manganese, and so on.

You’ll start to see more and more magnesium compound structures, particularly in front end applications.

Steel is cheap, and proven. Aluminum is expensive, and increasingly proven. Composites are still much too expensive.

Batteries are still much too expensive, but everyone hopes that scale will start to bring those costs down.

4

Since this requires speculation, let’s move it to IMHO.

Colibri
General Questions Moderator

5

Follow-up question: Assume new materials science allows us to decrease the weight of the car. Is there a lower limit to how much a car must weigh? Everyone likes lighter weight for increased acceleration, fuel efficiency, etc. But no one would want to drive a car that is too light. You wouldn’t want a car that could be blown off the road by the wind, for example. I assume a lightweight car would need a certain amount of ballast just to keep all four wheels on the surface.

6

There’s going to be a lot more carbon fibre than there is now. How much is going to depend on the vehicle, with the more expensive vehicles having more of it. The cost of fibre is coming down, it’s not going to stay too expensive for cars forever.

There was a report recently about how one could use carbon fibre to store electrical energy. It’d be a different and less strong form than the usual carbon fibre. The way they put it, carbon fibre is about twice as strong as steel (I assume on a per weight basis), but if it were made it a different way, which would be only about the same strength as steel, it could be used as an auxilliary battery.

I would not expect this to show up in cars in the next ten years, but perhaps in electric aircraft where the need to reduce weight is more important. Maybe some time after that for cars.

7

CFRP isn’t a panacea, however. it’s great where you need rigidity and where minimizing weight is critical. but it has shortcomings like unpredictable fatigue failure; most metals have fairly well understood fatigue failure modes.

also, CFRP would not be appropriate for the crumple zone structure . CFRP fails in a “brittle” manner, meaning it does not undergo any plastic deformation before fracturing. Metals like steel and aluminum, however, do bend. In a collision, the structure forward of the passenger cell is designed to collapse in a controlled manner. and as those metal structural members collapse (like an accordion) the rapidly deforming metal gets very hot which helps dissipate energy from the crash. A CFRP member would stay rigid up to the point where the matrix separates, then shatter.

8

Isn’t carbon fibre already used in some cars? Wouldn’t that help with the predictability issue?

9

Yes, but not for body structures in mass market cars. There are a couple of supercars that use it for structure, but the body structure of a supercar has nothing in common with market cars.