F1technical.net

Why are people so keen to see carbon fibre in road cars when we still have steel bodywork panels? High grade aluminium body would surely be a better alternative today... at least it has a longer live span when you take into account oxidation.

Carbon in everyday road cars is massively jumping the gun...

agreed, but aluminium is far less pressable than steel
and so can only be used (in any quantity) as less curved panels (than steel), which is disadvantageous
always was that way, and always will be

anyway (they tell us), soon we'll be electric and a bit of weight won't matter with all that nice regeneration !

marcush. wrote:one important point is:
for weight savings composite ,not carbonfibre is what is driving the weight down.
In fact a glassfibre skin can be made lighter than carbonfibre ,which is very hard to get a closed surface with no telegraphing ..
so a nomex paper core with glass skins is what you need to make a ultralight panel.
I´d guess most of the cf use in car production is just a matter of being fancy.It´s a bit like the EV vehicle hype.

from my own AoA experience, I can say that "telegraphing" is more a case of a proper use of resin, curing and post cure, polyester and vinyl resins are much more prone to this than epoxy(which costs a lot more, like 3-4 times more expensive than polyester), and the better you compress the laminate, the less it may show, because it has to do with fibers having enough flexible (resins, some more than others, even cured, are still flexing/streching) material between them to move around

autoclaves only advantage is the additional pressure you may put on the part to compress the laminate more, everything else, like curing temp and post cure can be achieved without the pressure chamber

and I have no idea how you can make a lighter skin from glass than from CF with the same strength properties (I already explained that telegraphing is a non-issue with CF), it just makes no sense to me at all

on the other hand, if you want to go the cheap/easy way, spray or hand lay up is the way to go, and this is where you go for glass + polyester or vinyl resins (CF will not work well with these resins, saturation is sort of an issue), but these parts are in no way structural or lightweight compared to aluminum, or even steel counterparts, good for prototyping or low volume production though

I also think that the people who have never worked with composite laminates might imagine this to be a wonder technology that makes manufacturing complex things very easy, it is not actually, there are many tricks to get consistent good results even in low volume production of complex geometries, especially when the parts get small and have tight radiusses, on the other hand you have hydroforming, which has made it quite easy to shape metal (alu/steel) in almost any imaginable shape with easely repeatable success and is very adaptable to high volume production

hydroforming is not a gamechanger for mass production, though ?
I suppose it could be/is useful for niche products ?

any more hydroforming expertise/experience out there ?

Do they use similar machines in F1 cars like this one? Hypnotizing to watch

[youtube]http://www.youtube.com/watch?v=j19na8LMBnE[/youtube]

Nando wrote:Do they use similar machines in F1 cars like this one? Hypnotizing to watch

MORE!! I NEED MORE OF THIS IN MY LIFE! amazing!

aussiegman wrote:

Jersey Tom wrote:Only reason it's used is for marketing.

That's a very cynical and myopic view of the situation I think.

If it gave no benefit other than marketing then its usefulness would be limited and we wouldn't be seeing the recent expansion in it use. Companies like Audi, Porsche, Mercedes and BMW (see a pattern there, cost and Euro based design where efficiency is the primary driver) now have used composites in their production cars.

Is it nearsighted of me? Maybe, in the sense of that's the status quo. I call it like I see it. The pattern that I see incidentally is that those are all premium or high cost manufacturers whose target demographic are people with high amount of disposable income, who are willing to dispose of even more of it if attracted by some fancy new widget or "performancey thing" they can be sold on. I would not put them under the title of "efficiency-oriented" OEMs. Tata Motors I could see being under that umbrella - appeal to broad market, get the most you can for the least cost. How much CRFP are they using, or how much is in other broad market cars? Toyota Corolla? Nissan Sentra? Renault Clio?

There are plenty of high strength-to-weight materials out there. Various alloys of steel meet that bill very well, as well as aluminum. What is the advantage of fiber reinforced materials? I'd say primarily it's the directionality you can achieve. High strength or stiffness in one orientation at the expense of another by taking advantage of an anisotropic material. What specific applications on a broad market consumer car can stand to be substantially improved by composites?

There's a time and a place for carbon. I don't see the screaming needs for it on OEM application, and I do maintain that a primary use for it at the moment is just for marketing. Just the same as absurdly wide and low profile tires and large bead diameter wheels.

Awhile back the very green Rocky Mountain Institute undertook the simple task of designing the efficient car it had called for. So far the only reported result is a thermoplastic/carbon composite suitable for mass production by injection molding. An example of the process in the form of a bowl was exhibited. It rang like a bell, a quality that could be a drawback when used as a fender. Other concerns come to mind.

If carbon composites aren’t primarily image features, I wonder why there’s so much faux carbon composite splashed around.

It's worth keeping in mind too that you don't need to use lots of composites or exotic alloys... there are other ways to save weight. They can potentially be advantageous in that regard, but you can drop weight with standard, readily available, relatively inexpensive alloys with some clever mechanical design...

jz11 wrote:

marcush. wrote:one important point is:
for weight savings composite ,not carbonfibre is what is driving the weight down.
In fact a glassfibre skin can be made lighter than carbonfibre ,which is very hard to get a closed surface with no telegraphing ..
so a nomex paper core with glass skins is what you need to make a ultralight panel.
I´d guess most of the cf use in car production is just a matter of being fancy.It´s a bit like the EV vehicle hype.

from my own AoA experience, I can say that "telegraphing" is more a case of a proper use of resin, curing and post cure, polyester and vinyl resins are much more prone to this than epoxy(which costs a lot more, like 3-4 times more expensive than polyester), and the better you compress the laminate, the less it may show, because it has to do with fibers having enough flexible (resins, some more than others, even cured, are still flexing/streching) material between them to move around

autoclaves only advantage is the additional pressure you may put on the part to compress the laminate more, everything else, like curing temp and post cure can be achieved without the pressure chamber

and I have no idea how you can make a lighter skin from glass than from CF with the same strength properties (I already explained that telegraphing is a non-issue with CF), it just makes no sense to me at all

on the other hand, if you want to go the cheap/easy way, spray or hand lay up is the way to go, and this is where you go for glass + polyester or vinyl resins (CF will not work well with these resins, saturation is sort of an issue), but these parts are in no way structural or lightweight compared to aluminum, or even steel counterparts, good for prototyping or low volume production though

I also think that the people who have never worked with composite laminates might imagine this to be a wonder technology that makes manufacturing complex things very easy, it is not actually, there are many tricks to get consistent good results even in low volume production of complex geometries, especially when the parts get small and have tight radiusses, on the other hand you have hydroforming, which has made it quite easy to shape metal (alu/steel) in almost any imaginable shape with easely repeatable success and is very adaptable to high volume production

one for one a cfk skin is stronger than a glass skin ,but that was not my point .If you need stiffness and strength it may be more intelligent to go for core thickness instead of skin strength.I´d think in automotive industry the matter of core thickness is a non issue especially considering benefits in terms of crash worthiness.

A quite hands-on thesis on the subject ,unfortunatelly in german ...
http://wiki.r-g.de/images/9/99/Disserta ... _Funke.pdf

g-force_addict wrote:Maybe FIA should give some rewards for teams that use out of autoclave carbon fiber parts?
In order to allow opportunity for smaller teams and to smooth carbon fiber transition to every day cars.
Some say autoclave only adds a minimal strength increase at a huge cost and delay:

Autoclave cured composites mostly benefit from having a better fiber fraction than vacuum bagged/oven cured laminates. There is little difference in the cure cycle times between the two processes, but ovens are cheaper than autoclaves, and much larger parts/tools can be used with ovens versus autoclaves.

There are some very good resins/pre-pregs now available for out-of-autoclave use. However, I think the future of very high strength composites will be with thermoplastics and carbon tapes. The laminates will be produced by CNC tape laying machines that apply strips of carbon fiber tape with a layer of thermoplastic adhesive, to a tool surface. While the machine applies this tape, it will also pretension the fibers, apply compression to the laminate, and thermally cure the thermoplastic adhesive film. This will result in a laminate with properties far superior to even those produced in an autoclave.

As for using composites in production automotive applications, it's not the cure cycle time in the autoclave or oven that presents the worst problem. It's the amount of time it takes to lay up the part in the tool.

I would have thought that repair and defect testing/monitoring would be one of the big reason why you wouldn't make many parts of a car out of carbon fiber. It would be a big change for the local body shop.

Body panels that are designed just to be thrown away could be made out of plastics if they could produce good colour/finish in a reasonable time though.

Jersey Tom wrote:

aussiegman wrote:

Jersey Tom wrote:Only reason it's used is for marketing.

That's a very cynical and myopic view of the situation I think.

If it gave no benefit other than marketing then its usefulness would be limited and we wouldn't be seeing the recent expansion in it use. Companies like Audi, Porsche, Mercedes and BMW (see a pattern there, cost and Euro based design where efficiency is the primary driver) now have used composites in their production cars.

Is it nearsighted of me? Maybe, in the sense of that's the status quo. I call it like I see it. The pattern that I see incidentally is that those are all premium or high cost manufacturers whose target demographic are people with high amount of disposable income, who are willing to dispose of even more of it if attracted by some fancy new widget or "performancey thing" they can be sold on. I would not put them under the title of "efficiency-oriented" OEMs. Tata Motors I could see being under that umbrella - appeal to broad market, get the most you can for the least cost. How much CRFP are they using, or how much is in other broad market cars? Toyota Corolla? Nissan Sentra? Renault Clio?

There are plenty of high strength-to-weight materials out there. Various alloys of steel meet that bill very well, as well as aluminum. What is the advantage of fiber reinforced materials? I'd say primarily it's the directionality you can achieve. High strength or stiffness in one orientation at the expense of another by taking advantage of an anisotropic material. What specific applications on a broad market consumer car can stand to be substantially improved by composites?

There's a time and a place for carbon. I don't see the screaming needs for it on OEM application, and I do maintain that a primary use for it at the moment is just for marketing. Just the same as absurdly wide and low profile tires and large bead diameter wheels.

BMW are shifting towards introducing more and more carbon on their cars, their plan together with SGL is to mass-produce carbon fiber.

It´s not far off before the first proper carbon car rolls off the production line, (that is not a sports car or hypercar)

browney wrote:I would have thought that repair and defect testing/monitoring would be one of the big reason why you wouldn't make many parts of a car out of carbon fiber. It would be a big change for the local body shop.

Body panels that are designed just to be thrown away could be made out of plastics if they could produce good colour/finish in a reasonable time though.

Consider it like this: If you need to produce say 100K unibodies per year, that requires spitting one out about every 5 minutes. It would take about 4 hours to lay-up and cure a composite chassis part under the best of circumstances. So this would require around 48 duplicate sets of tooling for each part. This tooling cost would be prohibitive for any automotive application.

riff_raff wrote:

browney wrote:I would have thought that repair and defect testing/monitoring would be one of the big reason why you wouldn't make many parts of a car out of carbon fiber. It would be a big change for the local body shop.

Body panels that are designed just to be thrown away could be made out of plastics if they could produce good colour/finish in a reasonable time though.

Consider it like this: If you need to produce say 100K unibodies per year, that requires spitting one out about every 5 minutes. It would take about 4 hours to lay-up and cure a composite chassis part under the best of circumstances. So this would require around 48 duplicate sets of tooling for each part. This tooling cost would be prohibitive for any automotive application.

Cycle times are the limiting factor .As i understand the Mclaren Tub manufacturing process is incredibly quick.BMW are possibly the leaders in the mass production having done big roof panels for the M3 since some years now in cooperation with SGL .
The real progress is with thermoplastic matrix especially when it comes to recycling of the whole lot...