The cost of a carbon fiber car chassis

[mastermechanic]

Hello everyone!

We're getting prepared to an electromobile car efficiency challange as a team. I'm going to take place in the chassis and exterior design team. I have lots of question but today I'm going to ask one of them.

How much does it cost us to produce an ordinary car chassis? I'm trying to reduce the weight as possible. Actually the word "ordinary" is not compatible with our challenge because the car will be relatively light and small, so chassis will not have the same complexity with an ordinary car. We won't do this directly but I'm just trying to have a general idea about that, of course we will have further research.

So what do you think? How much does it cost to produce an electromobile car chassis with carbonfiber?

 

[berkeman]

Asking about high-volume production costs of regular car chassis probably is not a good comparison to custom chassis design and fabrication in very low volume. You could look at the costs of custom race car chassis design and fabrication for a better comparison, maybe.

Also, have you looked at the light-weight chassis designs and fabrication that go into the solar car challenges? That is probably a lot closer to what you are working on...

http://funds.gfmcdn.com/8601175_1453830842.7134.jpg

 

[CWatters]

I think things like bucket seats for go carts are made from 4-6 layers of 2-300g/sqm cloth with something in between like a foam. Chassis for a light weight car might be similar? How many square meters of carbon cloth would that be? Perhaps double the cost of that to cover the cost of the mould, resin and sundary other things like reinforcement patches. Add something for metal fixing points?

One issue is changes. Much easier to change a welded tube chassis than to change the mould and make a new carbon one.

 

[mastermechanic]

Asking about high-volume production costs of regular car chassis probably is not a good comparison to custom chassis design and fabrication in very low volume. You could look at the costs of custom race car chassis design and fabrication for a better comparison, maybe.

Also, have you looked at the light-weight chassis designs and fabrication that go into the solar car challenges? That is probably a lot closer to what you are working on...

http://funds.gfmcdn.com/8601175_1453830842.7134.jpg
View attachment 221991

Nope, unfortunately :(. We're going to design a car that's very similar to the normal ones actually I can say it will be a "real" car. The race inspectors are going to examine the car in terms of security as well, if they don't find it reliable we'll be disqualificated. So, almost everything that exist in regular car chassis should exists in our car (chassis legs, roll bars etc.)

Since it's an efficiency challenge, I thought, even though it's expensive, if the performance/cost is high, it worths to design it with carbon fiber.

 

[anorlunda]

I didn't find much on cost. But I did see a lot of carbon fiber DIY videos on Youtube.

I believe that commercial cars use carbon fibers plus other materials in their frames. Of course the best guess for other materials is steel. But how much steel and where are open questions.

Whoever builds it safely will have to do a full strength/stress/tortion/bending analysis first. I don't know how much you consider expensive, but I would not be surprised by $100K just for analysis and design.

Of course you can skip some analysis by overbuilding it bigger and heavier than the absolute minimum. But that conflicts with your desire for minimum weight and maximum efficiency. You must think about that carefully because you may reach the point where and additional 10% decrease in weight costs 1000% more. In other words, expect a cost-efficiency curve to look like this.

A car is smaller than a boat, but more complex. This link http://www.sailingscuttlebutt.com/2013/09/26/cost-compete-34th-americas-cup/
says that the cost of an America's Cup sailboat challenge is about $200 million.

But to win your competition, you don't need the world's most efficient car. You need one only slightly better than the 2nd place competitor. That is challenging.

 

[berkeman]

We're going to design a car that's very similar to the normal ones actually I can say it will be a "real" car. The race inspectors are going to examine the car in terms of security as well, if they don't find it reliable we'll be disqualificated. So, almost everything that exist in regular car chassis should exists in our car (chassis legs, roll bars etc.)

Which brings up an important question -- Are people going to actually drive around in this car? At what speeds? If the chassis fails while it is being driven, what are the risks to the driver and nearby pedestrians?

 

[mastermechanic]

I didn't find much on cost. But I did see a lot of carbon fiber DIY videos on Youtube.

I believe that commercial cars use carbon fibers plus other materials in their frames. Of course the best guess for other materials is steel. But how much steel and where are open questions.

Whoever builds it safely will have to do a full strength/stress/tortion/bending analysis first. I don't know how much you consider expensive, but I would not be surprised by $100K just for analysis and design.

Of course you can skip some analysis by overbuilding it bigger and heavier than the absolute minimum. But that conflicts with your desire for minimum weight and maximum efficiency. You must think about that carefully because you may reach the point where and additional 10% decrease in weight costs 1000% more. In other words, expect a cost-efficiency curve to look like this.

View attachment 222053

A car is smaller than a boat, but more complex. This link http://www.sailingscuttlebutt.com/2013/09/26/cost-compete-34th-americas-cup/
says that the cost of an America's Cup sailboat challenge is about $200 million.

But to win your competition, you don't need the world's most efficient car. You need one only slightly better than the 2nd place competitor. That is challenging.

Wow! Actually I didn't expect that much ($100K). That would be impossible for us to afford this even though we're in search of sponsorship. But I agree with you, I imagine that the cost will increase with the efficiency desire. Since the chassis is the critical part for car in terms of weight, I'm responsible for it. I should keep it light and safe. Probably, Aluminum (or maybe steel) is the best choice.

 

[mastermechanic]

Which brings up an important question -- Are people going to actually drive around in this car? At what speeds? If the chassis fails while it is being driven, what are the risks to the passengers and nearby pedestrians?

Umm, the race rules and restrictions are a little bit complicated, there are lots of them. Yes, all teams have to have drivers and they'll drive it in specific racetrack. There is no limitation about the speeds, the main purpose is to have the least energy consumption after 60 tours.

Also, there're many subcategories which will be also evaluated, Design, Performance, Number of parts which are domestic products etc.. They have different prizes.

 

[CWatters]

Seems to me you need to look at the Shell mileage marathon cars. Low drag, low rolling resistance and a very efficient engine and drive train.

 

[mastermechanic]

Seems to me you need to look at the Shell mileage marathon cars. Low drag, low rolling resistance and a very efficient engine and drive train.

Yes, the concept is very similar except for the cars in our challenge should look like a normal car. Thanks by the way, I'll search what's been done in Shell's marathon.

 

[CWatters]

What does a "normal" car look like? Some cars from the past have had pretty extreme aerodynamics..

An illustrated history of automotive aerodynamics..

http://www.thetruthaboutcars.com/20...ry-of-automotive-aerodynamics-in-three-parts/

The current record holder for mass-production cars is the Mercedes E 220 CDI Blue Efficiency Coupe, with a Cd of 0.24. Undoubtedly, that will be broken before long.

That's pretty good even compared to some one off specials.

Perhaps see papers like...
http://www.kms.polsl.pl/mi/pelne_21/05_21_52.pdf

 

[berkeman]

An illustrated history of automotive aerodynamics..

http://www.thetruthaboutcars.com/20...ry-of-automotive-aerodynamics-in-three-parts/

Interesting article, thanks. This picture made me pause for a few seconds, as my brain tried to decode it...

http://www.thetruthaboutcars.com/wp-content/uploads/2010/02/Capture.png

 

[mastermechanic]

What does a "normal" car look like? Some cars from the past have had pretty extreme aerodynamics..

An illustrated history of automotive aerodynamics..

http://www.thetruthaboutcars.com/20...ry-of-automotive-aerodynamics-in-three-parts/
That's pretty good even compared to some one off specials.

Perhaps see papers like...
http://www.kms.polsl.pl/mi/pelne_21/05_21_52.pdf

Yes, but this competition is carried out by an institution in Turkey and I guess there is a research to create the domestic production car in the background of this competition. So, institution wants us to design a car which has high producibility, efficiency, performance and esthetic. Probably these are preparations of a mass-production of domestic car, so it should look like the cars on the streets that's why I called "normal car" .

 

[CWatters]

So, institution wants us to design a car which has high producibility, efficiency, performance and esthetic.

Car manufacturers spend billions trying to achieve those objectives. They make so many cars that every $1 they can save earns the company $millions. They are still largely made of metal because metal works out cheaper and faster to make. You can press steel in seconds, where as composites take hours.

 

[gleem]

For some pricing on carbon fiber matting check out the marine supply co. Jamestown Distributor for types of cloth and pricing plus epoxies, core mat'l, etc. For example a heavy duty mat 50 inches wide (19.8 oz./yd) goes for about $39/yd. The also have assorted videos for different projects that may be of value to you.

 

[CWatters]

On Alibaba you can find the price per ton for steel and lower quantities of carbon. I think carbon is about four times the price but that doesn't include resin or labor needed to do the lay-up. Autoclave time?

 

[gleem]

In marine construction the special process is vacuum bagging the laminate.

 

[256bits]

So, institution wants us to design a car which has high producibility, efficiency, performance and esthetic. Probably these are preparations of a mass-production of domestic car

Is that a guess what they desire, or your interpretation.
Concept vehicles provide a gateway for some options that may or may not be incorporated into mass production, sometimes many years after the fact.
What is designed and thought of by the team as the greatest, may be shrugged off by the buying public as undesirable, or the manufacturer.
Really no way to know.

Example - side mirrors, at higher speeds they produce air drag , what % I do not know, but that drag from a protrusion could be eliminated to a major extent by using rear facing cameras and video feed into the interior of the car. Why do not all cars have that? Is it because the public does not find that as an appealing gadget amongst all the others they are bombarded with? Do manufacturers find the addition ineffective on the retail price and sales? Would it mean a car doesn't look like a car anymore without mirrors and "someone" has decided that way? Perhaps it is that present transport laws dictate that side mirrors are mandatory on all production cars? Whose to know?

 

[mastermechanic]

Is that a guess what they desire, or your interpretation.

Example - side mirrors, at higher speeds they produce air drag , what % I do not know, but that drag from a protrusion could be eliminated to a major extent by using rear facing cameras and video feed into the interior of the car. Why do not all cars have that? Is it because the public does not find that as an appealing gadget amongst all the others they are bombarded with? Do manufacturers find the addition ineffective on the retail price and sales? Would it mean a car doesn't look like a car anymore without mirrors and "someone" has decided that way? Perhaps it is that present transport laws dictate that side mirrors are mandatory on all production cars? Whose to know?

Yeah you're right, electronic side mirrors has been started to be used in some car brands. It was a interpretation but in the competition booklet it says "
Visual Design Award /// This award will be given to the team whose vehicle’s external and internal design (shell, cockpit etc.) is original and aesthetically pleasing. The award also considers the designs industrial producibility and usability." So I think, doing something like Tesla has much more advantage then doing like streamlined design. It's should have also a muscular body and sportive lines like today's cars.

 

[berkeman]

It's should have also a muscular body and sportive lines like today's cars.

Have you looked at current-day concept cars for ideas? Like the concept cars shown at the major auto shows...

https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2013/8-hybridsconce.jpg

 

[mastermechanic]

Have you looked at current-day concept cars for ideas? Like the concept cars shown at the major auto shows...

https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2013/8-hybridsconce.jpg
View attachment 222181

Yes, I've still looking at for some reference. I have a concern about how to model my sketches because even though I reach a final design on paper I have to model it so that it can be manufactured with metal or plastic sheets. How can I model that curves on the body?

 

[Sherwood Botsford]

If the ability to manufacture in bulk is important, then skip carbon fibre. You don't save enough weight to be worth the cost.

In addition, working with fiberglass and resin layups is standard technology. Carbon fiber is still pretty high tech.

Safety is a concern. First of all, a lighter weight vehicle will subject the occupants to larger accelerations in a collision. Modern cars are designed with crumple zones that absorb energy in a collision. You have to absorb more energy and do it with less mass.

 

[gleem]

In addition, working with fiberglass and resin layups is standard technology. Carbon fiber is still pretty high tech

Actually the techniques for laying up carbon fiber, fiberglass or Kevlar are the same Lots of video to show this.

 

[Tom Kunich]

Wow! Actually I didn't expect that much ($100K). That would be impossible for us to afford this even though we're in search of sponsorship. But I agree with you, I imagine that the cost will increase with the efficiency desire. Since the chassis is the critical part for car in terms of weight, I'm responsible for it. I should keep it light and safe. Probably, Aluminum (or maybe steel) is the best choice.

I have had carbon fiber components fail. I don't believe you will find CF in the frame or suspension components of a car but rather non-structural areas to reduce weight. And you can probably use aircraft grade aluminum more effectively and a great deal cheaper. And a whole hell of a lot less likely to fail. The strength of CF components relies a great deal on the strength of the resin holding it together. Over catalyzed resin or older structures can fail as the resin slowly ages and becomes increasingly brittle. I have had endless arguments with people who believe that CF is the future. But I am also permanently injured from failures from the best manufacturers.

 

[Sherwood Botsford]

Actually the techniques for laying up carbon fiber, fiberglass or Kevlar are the same Lots of video to show this.

Yes and no. Cutting the cloth is different. Because of CF stiffness you have to pay more attention to ply orientation. Different resins. Almost always using vacuum bag techniques. For making dog sleds, not much different. For making airplane wings, a lot different.

 

[Nuke]

You can buy one of these from Alfa Romeo for $55K. Already to roll, carbon fiber chassis.

 

[professor x]

I worked on carbon fiber elements for formula SAE. Total cost depends on the quality and amount of used materials - carbon fiber, epoxy resin, hardener. For vacuum infusion process you will also need molds, infusion mesh, infusion spirals, peel-ply, silicone bags etc. Vacuum pump and oven/autoclave can be expensive, but they are one-off costs.

If it is your first time with carbon fiber composites, watch some tutorials on YouTube. For safety reasons, always wear latex gloves when you use epoxy resin and dust mask during cutting the material.

 

[berkeman]

I worked on carbon fiber elements for formula SAE. Total cost depends on the quality and amount of used materials - carbon fiber, epoxy resin, hardener. For vacuum infusion process you will also need molds, infusion mesh, infusion spirals, peel-ply, silicone bags etc. Vacuum pump and oven/autoclave can be expensive, but they are one-off costs.

If it is your first time with carbon fiber composites, watch some tutorials on YouTube. For safety reasons, always wear latex gloves when you use epoxy resin and dust mask during cutting the material.

Thanks X.

But did you folks use CF for the chassis of your SAE cars? Seems like a strange match of properties to requirements, especially for any type of volume production...

 

[anorlunda]

I worked on carbon fiber elements for formula SAE

Does that mean this? https://en.wikipedia.org/wiki/Formula_SAE

That race sounds like something needing lots of money. Wikipedia talks about funraising and corporate sponsors, but it does not give any numbers for the budgets of these teams. One thing lacking from this thread is an order-of-magnitude guess for the budget. We don't know if the original post envisions a one thousand dollar budget or one million.

Perhaps you can help with your knowledge of formula SAE competition. I'll repeat the original question.

So what do you think? How much does it cost to produce an electromobile car chassis with carbonfiber?

 

[professor x]

But did you folks use CF for the chassis of your SAE cars? Seems like a strange match of properties to requirements, especially for any type of volume production...

We didn't use carbon fiber for chassis. We used it for external bodywork, aerodynamic devices such as front wing, rear wing, and other elemets, for example steering wheel. Some teams, which have more experience, build carbon fiber monocoque that can decrease the amount of steel.

Does that mean this? https://en.wikipedia.org/wiki/Formula_SAE

That race sounds like something needing lots of money. Wikipedia talks about funraising and corporate sponsors, but it does not give any numbers for the budgets of these teams. One thing lacking from this thread is an order-of-magnitude guess for the budget. We don't know if the original post envisions a one thousand dollar budget or one million.

Yes
Most of the costs were covered by sponsors. It's hard to say how much it cost. A lot of stuff we received for free and we had many discounts . Whole vehicle cost about 15000$, while aerodynamics budget was 2000$.