Quote:
Originally Posted by Captain Awesome
You assume that I believe that "composites" are 100% carbon fiber, which they are not.
The original Saturns and 4th Gen F-Bodies, as well as a few GM Minivans were made of "composite" body panels, which is a generic term that doesn't mean "carbon fiber".
As I said above, carbon fiber is a great lightweight and strong material, but it is very brittle and is prone to damage and failure from fatigue, etc. This is well documented in the field of aircraft design. It also costs a LOT more to produce than metal alloys. For the most part it doesn't pay for itself in weight savings and the manufacturing process for the material has a rather beefy "carbon footprint". Once everyone is fully committed to building cars with it, someone will figure out that it must be helping kill polar bears and we'll be back to square 1 with some even more expensive process making cars even more unobtainable.
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No, actually I didn't. As I said, I worked on (and still work on) vehicles using extensive amounts of composites and plastics and I know that composites mean other materials so when I know why would I assume you don't?
CF just happens to be the poster child for two reasons I believe 1) generally it's the biggest mass savings and 2) show carbon like I have on my Ducati looks sweeeeeeet
Most of the composites you are thinking of have one big benefit and that is low tooling costs. A door inner panel for example would take 5 dies to make it from steel or aluminum (4 if you are lucky, good or both). And aluminum isn't cheap either so that is also one of the reasons composites (plastics) are favored on low volume applications like Corvette or special runs vehicles.
The CF materials used in the automotive applications won't be sensitive to fatigue. They are in fenders or roof panels that aren't stressed very much. In the Boeing Dreamliner though, the CF is structural and that may be what caused the brief recall.
Also SMC is much cheaper than CF and that works well in structural applications as well, it is just not as light.
Injection molded plastics also have applications for fenders. They were used on the Gen IV Camaro fenders and also on the old G bodies. The problem with those was thermal expansion. Similar to the old Saturns your door gaps change with temperature and to allow for expansion you have to have larger gaps than is considered good today. I think the Saturns had 6+ mm gaps all around the car.
You are absolutely correct in your point that they won't pay for themselves, at least in my opinion. Many of the OEMs as well as the dealers this past week have been telling us that the high cost of FE will drive many people out of the market costing millions of sales per year.
Yes, you can save 100, 200 or even 300 pounds on a car using composite materials but at a PREMIUM price relative to steel, or conventional materials. So how much? A bunch and we can leave it at that but it isn't a few hundred $ as the Group of Concerned Scientists will try to tell you. (BTW, did you know they aren't Scientists and I'm not sure they are Concerned about the same things we are)
Now if you add a hybrid battery into the equation, you have to save even more weight just to be even.
So back to the original point on the Mustang weighing 300 pounds less sure it is possible. With downsizing and clever engineering it should be no problem. And if you do it well, you can make a car smaller and maintain a roomy interior. The 3 Series is a good example of that. I think they actually made the new one a little bigger and still cut some weight out over the previous model. Look at the weight of the Hyundai Sonata, I think it's about 3200 pounds or so and yet it is roomy and does a lot of things very well.
Just watch out for the weight savings that comes from simply having a base 4 cyclinder engine. That alone with the smaller transmission you can use and the smaller axle can result in a good chunk of that 300 pounds.