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New lightweight material is stronger than steel

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Re: New lightweight material is stronger than steel

#131

Post by DannyBee »

riskable wrote: post #111

I can't believe no one has mentioned this: The researchers claim this material is completely impervious to gasses . Does that mean we've finally got a way to store hydrogen without having it constantly leaking away?

They said impermeable, not impervious.

There are lots of coatings and materials that are impermeable to liquids and gases. For starters, they did not say it was inert (like say, PFTE, which is super low energy), so just because it's impermeable doesn't mean it won't get attacked by gases or solvents. Most polymers are.

Re: New lightweight material is stronger than steel

#132

Post by DannyBee »

throwaway4aday wrote: post #10
soperj wrote: post #8

Wonder if it work as a rebar replacement that doesn't rust.

Just coat the rebar, one of its properties is that it's impermeable to liquids and gases.

Lots of problem here - it doesn't expand/contract at the same rate. So it will likely delaminate over time.

It is also not inert. So it may in fact, be attacked by soil PH, etc (maybe not, not enough info in the article).

Also, one of the problems with coating most things is achieving good enough adhesion that it both doesn't delaminate, and that molecules can't slip through.

Re: New lightweight material is stronger than steel

#133

Post by ghaff »

hutzlibu wrote: post #117
ghaff wrote: post #108

Earlier quoted context omitted.

>Several major accidents (including the top of an airliner coming off and sucking a flight attendant out over the pacific on the way to Hawaii) It was actually an inter-island flight so lots of short flights (and therefore pressurization cycles relative to flight hours or miles). The amazing thing was that the plane was able to make an emergency landing. https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243

So this was in 1988? I would have suspected this story was out of the early days of the big airliners.

The earlier days of big airlines involved mostly pretty long distance travel. So the issues were mostly of a different nature.

Re: New lightweight material is stronger than steel

#134

Post by lazide »

gm3dmo wrote: post #128
lazide wrote: post #94

Earlier quoted context omitted.

Titanium even more so. For those, they are actively swapped around where cost vs weight trade offs happen. steel vs aluminum vs magnesium, vs titanium in engineering application, where for example engine blocks, airplane parts, car parts, battery components, etc. all have a long history of this. It’s a complicated process because the trade offs are not simple cost/weight/strength. Steel has an nearly infinite fatigue…

+1 for thorough but: > Titanium is in theory much better, but is incredibly difficult to work with(requiring forgings in most cases, and being almost unmachinable), and very expensive as the bond it forms with oxygen is so strong the normal fluorine based processing used with Aluminum won’t work. Yeah, you read that right. I have a spoon bought from Amazon which they claim is made from titanium. [Lockheed_SR-71_Black…

If it is the same type of spoon I’m thinking of - they are indeed titanium! Forged titanium, at least the version I got.

Because it’s a small part with no significant critical tolerances, it’s also only $10-$20 for a few grams of metal, and only 5x as expensive as a typical spoon.

The equipment required to forge it is also doable in a garage due to the small surface area the forging is happening over (force required goes up as the surface area goes up - which is squared for the dimensions, so very rapidly gets very large).

Compare that to say an engine block, wing spar in an airplane, or fighter jet bulkhead [https://www.businesswire.com/news/home/20151007005865/en/Alc...] and it gets dramatically more expensive and harder.

It isn’t truly impossible to machine titanium (generally - like most metals the alloy, heat treatment, etc. matter a lot), it’s just so much harder and requires so much more expensive tooling that it’s hard to justify economically except in niche applications.

It’s improving though with better insert based machining tools and hardier insert material.

I’ve heard of some impressive titanium 3D printing using sintering techniques that also have a lot of promise.

Many of the alloys (many more than say aluminum) are nearly impossible due to material characteristics and do require EDM to machine.

Decades ago I happened to get a tour of the Edwards Air Force Base SR71 hangar (near the end of their effective time in service) and the machinists there were very proud of their EDM work for this reason.

Re: New lightweight material is stronger than steel

#135

Post by lazide »

ghaff wrote: post #133
hutzlibu wrote: post #117

Earlier quoted context omitted.

So this was in 1988? I would have suspected this story was out of the early days of the big airliners.

The earlier days of big airlines involved mostly pretty long distance travel. So the issues were mostly of a different nature.

Thanks for tracking down the specific incident! If I remember correctly, the obvious cycling issue got figured out pretty early (60’s?) - due to other earlier accidents, that part wasn’t a surprise and they thought they had figured out how to deal with it.

There was a presumption that like steel and several other materials, once it hit a specific low stress point the fatigue life became infinite, and that point was just so much lower for aluminum it just LOOKED like it has no infinitive fatigue life point.

It turns out they were wrong.

Re: New lightweight material is stronger than steel

#136

Post by lazide »

TylerE wrote: post #106
inglor_cz wrote: post #105

Earlier quoted context omitted.

Pressurization cycles is what killed the reputation of the first commercial civilian jet, the De Havilland Comet. The British were good in early jet design and actually introduced jet aircraft into the non-military world, but the early hulls would fail catastrophically after a certain, relatively low # of cycles, tearing the fuselage apart mid-flight and killing everyone on board. After several such incidents in shor…

That wasn't really a cycles issue exactly, it was they used square windows rather than round, leading to stress concentrations. Per your last point, BAE and Hawker are still around. The UK also does plenty of Airbus work.

The stress concentration became a big problem because of the fatigue cycles though didn’t it?

The manufacturers you mentioned are all military or regulatory sop manufacturers no? Though I guess Boeing isn’t much better, so meh.

Re: New lightweight material is stronger than steel

#137

Post by kardos »

solarmist wrote: post #130
kardos wrote: post #125

Earlier quoted context omitted.

https://en.m.wikipedia.org/wiki/Vacuum_airship Like a blimp but with a rigid balloon filled (ha ha) with vacuum instead of a light gas. The article is saying it's a polymer so I'm guessing it doesn't have the right rigidity, ie, the stronger than steel bit must be with respect to a different strength measure

....wow, that is the most counter-intuitive idea I've seen in a long time! A helium balloon makes sense, it's lighter than air so it floats, duh. Well, what's lighter than that? Nothing (vacuum)! It's such a dumb, but correct answer that I had a hard time wrapping my head around it. Yup, theoretically a vacuum would be extremely buoyant if we could put it in a light enough structure.

Yeah it's nifty idea -- no need for explosive hydrogen or scarce helium. If the polymer sheet is strong enough, I wonder if one could use it to wrap a sort of scaffolding (a shape like https://en.wikipedia.org/wiki/Fullerene but perhaps with struts through the interior for more strength), then evacuate the air from the interior in order to form a lighter-than-air "box". Submarines can withstand a few dozen atmospheres of pressure, this would have to withstand .. one, I suppose, so intuitively it seems plausible.

Re: New lightweight material is stronger than steel

#138

Post by worik »

dzhiurgis wrote: post #123
cooljacob204 wrote: post #36

Earlier quoted context omitted.

Also steel is 100% recyclable. If I recall correctly, most steel used today is recycled.

If this has 100x less carbon footprint and steel is 90% recycled, the polymer still wins overall.

Not in 10,000 years when it is still blowing around..

Re: New lightweight material is stronger than steel

#139

Post by worik »

As far as I can tell there is no analysis of what happens to the waste from this. In this day and age we have to consider the complete life cycle of a new material.

I am really hoping there are acceptable answers, it would be cool to have a new polymer like this

Re: New lightweight material is stronger than steel

#140

Post by dzhiurgis »

worik wrote: post #138
dzhiurgis wrote: post #123

Earlier quoted context omitted.

If this has 100x less carbon footprint and steel is 90% recycled, the polymer still wins overall.

Not in 10,000 years when it is still blowing around..

Current steel production is pretty awful too - radioactive materials in atmosphere via coal, leachates from additives, etc.

Microplastics haven't been proven to have much damage other than triggering karentils (karen's on lentil spectrum).

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