Carbon fiber is NOT stronger than aluminium and steel

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Z.hb71

Z.hb71

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I was always skeptical about when people say "carbon fiber is stronger than steel" and this guy put it to the test with structural steel, stainless steel, carbon fiber, and aluminum of all same diamentions
 
That's a very entertaining vid! I love watching that kind of stuff!

Stronger than steel is a bit of a misnomer when it comes to carbon fiber. At the same density, carbon fiber is a lot stronger than steel, but that's not reality. Carbon fiber is 1/5th the density of steel. So what you're looking at is strength to weight ratio. If you have a sheet of steel that weighs 10Kg and a sheet of carbon fiber of the same weight, the carbon fiber would definitely be stronger, but it would also be 5x thicker than the steel sheet.

CF has a ton of uses where a light, strong, rigid part is needed, but I'm never been a fan of most of the CF parts on big, heavy RC cars, especially in parts of the frame where it is subject to forces from multiple different directions. But hey, folks can get whatever they want with their money! :ROFLMAO:
 
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AnubisBC said:
Stronger than steel is a bit of a misnomer when it comes to carbon fiber. At the same density, carbon fiber is a lot stronger than steel, but that's not reality. Carbon fiber is 1/5th the density of steel. So what you're looking at is strength to weight ratio. If you have a sheet of steel that weighs 10Kg and a sheet of carbon fiber of the same weight, the carbon fiber would definitely be stronger, but it would also be 5x thicker than the steel sheet.

CF has a ton of uses where a light, strong, rigid part is needed, but I'm never been a fan of most of the CF parts on big, heavy RC cars, especially in parts of the frame where it is subject to forces from multiple different directions. But hey, folks can get whatever they want with their money! :ROFLMAO:
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Ah I see. I'm talking about RC use though. Most RC parts that they sell in Cf is the same thickness as their aluminum counterpart, like the Baja chassis, so the aluminum piece would be stronger correct?
 
Yes, if the same thickness, the Aluminum will typically be the stronger part, depending on the aluminum. The directional strength of carbon fiber depends on the direction of the weave. Here's a great example: driveshafts in F1 cars are made from CF, but the weave is specifically designed to withstand rotational torque (twisting). In that use, it's way stronger than steel, but also notice it is thicker. And if you were to apply any exertion on it from another direction while under that strain, it would likely fail. It will also snap abruptly when it fails, whereas metal will bend or twist prior to snapping.

Here's a fun one for ya:

I would totally use CF to lighten my car, but only in places that aren't subject to linear and lateral stress unless I could get a part that was much thicker than the aluminum counterpart. I do love the look of the stuff!
 
AnubisBC said:
Yes, if the same thickness, the Aluminum will typically be the stronger part, depending on the aluminum. The directional strength of carbon fiber depends on the direction of the weave. Here's a great example: driveshafts in F1 cars are made from CF, but the weave is specifically designed to withstand rotational torque (twisting). In that use, it's way stronger than steel, but also notice it is thicker. And if you were to apply any exertion on it from another direction while under that strain, it would likely fail. It will also snap abruptly when it fails, whereas metal will bend or twist prior to snapping.

Here's a fun one for ya:

I would totally use CF to lighten my car, but only in places that aren't subject to linear and lateral stress unless I could get a part that was much thicker than the aluminum counterpart. I do love the look of the stuff!
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Ahhh makes sense ?? thanks for educating me.
 
In addition,there are different types of cf strands also that influence the overall strength of the cf. Good example using drive shaft. You can "tune" cf for your intended purpose. Car chassis and structural pieces density are made differenly then other parts - say trim pieces/ non structural. Now carbonese fiberinesium is a different story. ??
 
@Striikar I hadn't meant to get into strand differences, because I wanted to keep the discussion at a high level, but you are absolutely right! Hobby sized CF parts are not engineered in the way that F1 driveshafts are. They're just a layered plate composed of multiple crossed small strands that are then milled to shape. On a light electric or nitro RC, it's of no consequence. You would have a very light frame with an extremely rigid shape, and the opposing forces are minimal due to its light weight. My electric stunt helis are exactly like that. They're extremely light, and there are no forces opposing their design in the air. That is, until they crash. Then all of those beautiful CF parts shatter like fiberglass. CF is amazing, but it isn't indestructible, and no 2 pieces are the same unless they are engineered for their specific purpose in the same lab.

And we haven't even delved into abrasion and its effects on CF structural integrity. But that's certainly one big reason to avoid a CF chassis for a large scale off-road car!
 
I've had CF towers on both the TLR SCTE 2.0 and 8ight 2.0 and never had a problem. In fact was surprised how well they held up.
 
AnubisBC,

I was expanding on your good basic info. I just didn't someone to think it's that simple and use that as a total summation of cf.
As we all know someone's going to use what they read and "oh that's all there is" as a definitive to whatever the subject is and never delve any deeper. It's why I used such large differences in cf pieces to make people at least wonder how the construction of such pieces differ.
I figured people would understand varying quality with my "Carbonese Fiberesium" phrase. ?
 
Striikar said:
I was expanding on your good basic info. I just didn't someone to think it's that simple and use that as a total summation of cf.
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Totes! There's a ton of great info out there to be had, and your addition is very welcome to this thread! I kind of approach CF parts in the same way as Aluminum parts. There are varying degrees of quality, and not all aluminum is the same.
 
AnubisBC said:
Totes! There's a ton of great info out there to be had, and your addition is very welcome to this thread! I kind of approach CF parts in the same way as Aluminum parts. There are varying degrees of quality, and not all aluminum is the same.
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Yeah, except aluminum is more simple, there's only specific grades (6061, 7075 ect) unlike cf were there's weave types, weave direction ect as you and @Striikar pointed out. Ok I'm going to go on a rant here, I hate when people say " oh aluminum is aluminum and cheap clone aluminum (integy, rovan ect) is no different than expensive rcmax aluminum(7075)" I hate when people say that! It's so damn ignorant! Like, people just don't pull prices out their ass, not to sound like a fan boy of rcmax, tr, phatdad, ect becuase that's not the case, I just understand why they are priced high.
 
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