3 ms·
To nitpick, the article uses the words 'tough', 'hard' and 'rigid' to describe this glass, though those all mean different things. I'd suggest that all glass i
by craigds 11y ago
To nitpick, the article uses the words 'tough', 'hard' and 'rigid' to describe this glass, though those all mean different things.
I'd suggest that all glass is both hard and rigid, so presumably 'tough' is what they're going for. If so, the glass should be able to withstand a large tensile force without fracture or permanent deformation.
'unbreakable' is also a little disingenuous. Everything is breakable, given a big enough hammer ;)
- such_a_casual 11y agoThey provided technical terminology when they explained that its Young's modulus is comparable to steel and iron. I agree that 'unbreakable' is clickbait even if it is quoted.
- dhdhxhx 11y agoThat still doesn't mean anything useful. That's just a measure of how much it changes shape per unit force in its elastic phase. It gives no indication about how far it can go changing shape in a reversible, elastic manner before it starts to yield and undergo permanent deformation. Now a stress-strain curve on the other hand, THAT would be useful.
- shawkinaw 11y agoYeah, the only justification for 'toughness' was the Young's modulus, which does not tell you how resistant it is to breaking at all. And by that measure, sapphire [1] is 2.5 times tougher than steel [2]. [1] E = 7.4e7 psi (http://rubicontechnology.com/company/sapphire http://rubicontechnology.com/company/sapphire) [2] E = 2.9e7 psi (https://en.wikipedia.org/wiki/Young%27s_modulus https://en.wikipedia.org/wiki/Young%27s_modulus)
- blt 11y agoDon'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.
- vlehto 11y agoYou 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 subject is already what I'd wish laymen had. So I really don't mean any offense.
- blt 11y agoNone taken, thanks for the info!
- personjerry 11y agoTo clarify, is fracture toughness the ability to withstand a sudden increase in energy?
- vlehto 11y agoNot 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 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 https://en.wikipedia.org/wiki/Charpy_impact_test Thanks for that comment. I need to clear this stuff bit more in my head.
- wobbleblob 11y ago> Everything is breakable, given a big enough hammer ;) Or time alone with my daughter! "child-proof" isn't a reassurance, it's a challenge
- aryehof 11y agoSo many of us can identify with that, and so well stated!