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Scientists develop 'unbreakable' glass almost as tough as steel

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Re: Scientists develop 'unbreakable' glass almost as tough as steel

#71

Post by personjerry »

vlehto wrote: post #52
blt wrote: post #37

Earlier quoted context omitted.

Don't think it's nitpicking at all. I came away unsure whether the new material is hard (scratch resistant) or tough (won't shatter when dropped). An article about a new material that doesn't make the distinction fails fundamentally.

You might find it interesting that toughness and "won't shatter when dropped" are different things. Toughness(G) = slowly absorb energy without fracture. Shattering is more dependable of: Fracture toughness(Kc) = (E*G)^0,5 Where E = modulus. That explains why plastics with low E shatter easily while being tough. Metals have additional hardening methods that allow them to go beyond this rule. PS. Your knowledge on the…

To clarify, is fracture toughness the ability to withstand a sudden increase in energy?

Re: Scientists develop 'unbreakable' glass almost as tough as steel

#72

Post by vlehto »

personjerry wrote: post #71
vlehto wrote: post #52

Earlier quoted context omitted.

You might find it interesting that toughness and "won't shatter when dropped" are different things. Toughness(G) = slowly absorb energy without fracture. Shattering is more dependable of: Fracture toughness(Kc) = (E*G)^0,5 Where E = modulus. That explains why plastics with low E shatter easily while being tough. Metals have additional hardening methods that allow them to go beyond this rule. PS. Your knowledge on the…

To clarify, is fracture toughness the ability to withstand a sudden increase in energy?

Not really.. I had kind of error there. It's still often toughness when you wish to study how material reacts to sudden increases in (kinetic)energy.

Fracture toughness describes relation between maximum tension and maximum depth of pre-existing crack that still doesn't launch phenomena called "fast fracture".

https://en.wikipedia.org/wiki/Fast_fracture

It's highly relevant in many cases, because most real world materials have microscopic cracks. And because the load where fast fracture might happen is often lot smaller than yield load.

Curiously Charpy impact test still indicates more toughness than fast fracture. But it's never used to quantify toughness in real life.

https://en.wikipedia.org/wiki/Charpy_impact_test

Thanks for that comment. I need to clear this stuff bit more in my head.

Re: Scientists develop 'unbreakable' glass almost as tough as steel

#73

Post by Someone »

Johnny555 wrote: post #66
Someone wrote: post #54

Earlier quoted context omitted.

A window could give way in either direction without being penetrated, for example by stretching out and permanently deforming. Risk for people inside is that it would give too much way, so that that pole hits your head.

If it's flexible it's not going to support the roof in a rollover -- the windshield is a structural part of the occupant cage.

"Permanently deforming" and "flexible" are different things. The crumple zone of a car isn't flexible, but does deform.

But yes, this probably would either limit what you can do there or necessitate design changes (just like it would glass with some new properties)

Re: Scientists develop 'unbreakable' glass almost as tough as steel

#74

Post by govspy »

nly wrote: post #35
govspy wrote: post #32

Earlier quoted context omitted.

>2. How would it handle for cookware? Will it last even if an ignorant person left it in the oven for hours on end? Pyrex has been around since the 1910s and doing this just fine ever since.

Pyrex will shatter if you take it out of a blistering hot oven and pour cold water on it (e.g. to let stuck on food soak).

I never said that Pyrex is unbreakable. But it certainly wont break just because "an ignorant person left it in the oven for hours on end".

Almost every material known to man will break/crack/shatter/do-something if you rapidly cool it from an elevated temperature.

Re: Scientists develop 'unbreakable' glass almost as tough as steel

#75

Post by govspy »

politician wrote: post #33
govspy wrote: post #32

Earlier quoted context omitted.

>2. How would it handle for cookware? Will it last even if an ignorant person left it in the oven for hours on end? Pyrex has been around since the 1910s and doing this just fine ever since.

Well, Corning sold the brand name Pyrex around 2000. A post-2000 Pyrex item may not have the same composition as the Corning product you're more familiar with.

The composition of the Pyrex glass sold in North America did change from borosilicate glass to soda-lime glass when the brand changed hands, yes. But the important thing about "glass not breaking at high temperatures" has much more to do with the annealing process than it does the type of glass.
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