Next Big Future - Latest Comments in Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

joshlbetts — Tue, 09 Jun 2009 14:16:29 -0000

Locked doors and guns.

But I don't think there were design flaws or shortcuts, I believe ASCE provided a report regarding the design and it followed the building code and established design provisions for the time and the calculations and details were provided to the public and they are still available for review as most calculations and drawings for structures are.

The engineer of record did his due dilligence, imho.

Now, connections being the weak point of a structure? Yeah, that's usually the case. Fireproofing is designed to last long enough for people to escape. That is it's purpose, to prolong the collapse. Designing the buildings to remain standing after an explosion? Very difficult and impractical. Everything would be a concrete bunker, so you stop the bombs from getting there in the first place.

As far as "my" nano-AL columns are concerned, I'm not familiar with the material and it would have to be thoroughly tested, similar to AISC and then again, after design provisions are established, you won't be able to design it to withstand a terrorist attack, because you have to establish the size of the explosion. And what are the limits on that?

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

Orion — Tue, 09 Jun 2009 00:24:31 -0000

The beams on the WTC were wrapped in sprayed asbestos. The initial
explosion ripped this off on the impact floor and burning jet fuel ran
down the central elevator shaft, creating a hell wind. There were a
lot of design flaws & shortcuts taken in the Towers that contributed
to their collapse but from the moment of impact it was just a matter
of "when". Even w/o these faults I doubt your insulated nano-AL
columns would have performed as well.

Oh, and stout locked cockpit doors with pictures of the burning Towers
on the pilots' side to remind them WHY the door stays locked in
flight. >:)

"So? The standard aluminum alloy that airplanes have been built out of for sixty years is 2024 and it is, ahem, as strong as steel and, ahem, 1/3 the weight"

Next time you take a flight get a window seat over the wings so you can watch them wag up and down. Airplanes can be designed with a relatively small safety factor because they really don't carry that much load, compared to a steel truss bridge or a skyscraper. I can see nano-AL applications in aircraft construction, fer shur. By the time the airplane burns it's already pancaked 40' into the ground so this doesn't matter. But fire safety is an important element in building design. Your average modern office contains materials that burn at 800°C - 1200°C w/o suppression so that tells you what you need to shoot for.

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

Orion — Tue, 09 Jun 2009 00:12:09 -0000

Oh, and stout locked cockpit doors with pictures of the burning Towers
on the pilots' side to remind them WHY the door stays locked in
flight. >:)

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

kmg4 — Mon, 08 Jun 2009 23:51:51 -0000

The most important question is not clearly answered :

WHAT is the cost increment of this, over standard aluminium?

If it is not too much higher, then we are in bidness.

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

joshlbetts — Mon, 08 Jun 2009 22:45:09 -0000

One word:

Fireproofing.

But for 9-11 events, I suggest armed pilots.

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

hrhrossaero — Mon, 08 Jun 2009 21:02:10 -0000

Ok, those are very good points. I'm also trying to understand how existing alloys require "rare and expensive metals". I suppose the 4% Cu in 2024 will add up.
http://www.alcoa.com/mill_p...
CHEMICAL COMPOSITION LIMITS (WT.%)
Si . . . 0.50 Zn . . . . . . . . . 0.25
Fe. . . 0.50 Ti . . . . . . . . . . 0.15
Cu . . 3.8-4.9 Others, each . . 0.05
Mn . . 0.30-0.9 Others, total . . 0.15
Mg . . 1.2-1.8 Balance, Aluminum
Cr. . . 0.10

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

nextbigfuture — Mon, 08 Jun 2009 20:19:05 -0000

http://asm.matweb.com/searc...

2024-T3 aluminum alloy material properties

Physical Properties Metric English Comments

Density 2.78 g/cc 0.1 lb/in³ AA; Typical

Mechanical Properties

Hardness, Brinell 120 120 AA; Typical; 500 g load; 10 mm ball
Hardness, Knoop 150 150 Converted from Brinell Hardness Value
Hardness, Rockwell A 46.8 46.8 Converted from Brinell Hardness Value
Hardness, Rockwell B 75 75 Converted from Brinell Hardness Value
Hardness, Vickers 137 137 Converted from Brinell Hardness Value
Ultimate Tensile Strength 483 MPa 70000 psi AA; Typical
Tensile Yield Strength 345 MPa 50000 psi AA; Typical
Elongation at Break 18 % 18 % AA; Typical; 1/16 in. (1.6 mm) Thickness
Modulus of Elasticity 73.1 GPa 10600 ksi AA; Typical; Average of tension and compression. Compression modulus is about 2% greater than tensile modulus

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

nextbigfuture — Mon, 08 Jun 2009 20:15:35 -0000

It is mentioned in the article that there are alloys that already have those features. The claim is that carbon nanotubes will be able to do this cheaper eventually. Plus they indicate that they can also further reinforce alloyed aluminum and other metals.

There is a need for actual cost and feature comparisons and an indication of how much reinforement is possible of different aluminum alloys.

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

hrhrossaero — Mon, 08 Jun 2009 20:04:38 -0000

So? The standard aluminum alloy that airplanes have been built out of for sixty years is 2024 and it is, ahem, as strong as steel and, ahem, 1/3 the weight.

And it was like that 60 years ago when we started using it...there are stronger alloys now but 2024T3 is still the standard. Anyone with a credit card can buy it in single sheets for about $15 and up from many suppliers such as http://www.wicksaircraft.com/ or http://www.aircraftspruce.com/ or http://www.airpartsinc.com/.

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

Orion — Mon, 08 Jun 2009 18:00:13 -0000

The melting point of steel is ~1900°C; the melting point of aluminum is ~660°C. The steel I-beams in the WTC didn't even start softening until they hit 900°C. Somehow I don't think we'll ever see aluminum skyscrapers. They'll use this in more NON-loadbearing, NON-heatproof applications, sure. I can see applications like aluminum-frame racing bikes. An aluminum wrench as strong as a cast-steel wrench would be great for my (heavy) toolbox.

Re: Carbon Nanotubes Make Aluminum as Hard as Steel But One Third the Weight

Brian Crouch — Mon, 08 Jun 2009 17:49:48 -0000

Imagine the bridges that could be built with that...