6 ms·
Sea snail teeth top Kevlar, titanium as strongest material (2015)
- gweinberg 2y agoMaterials that are strong under compression aren't necessarily strong under tension, and vice-versa. I would think teeth (just) need to be really strong under compression, and spider silk really strong under tension.
- potato3732842 2y agoStrength per weight vs strength per volume are an issue as well.
- hwillis 2y agoIt's tensile strength, not specific strength. Strength over an area. There also is no such thing as strength per volume.
- e28eta 2y agoI was curious about what they meant by strength, and the link at the bottom of the article says this is tensile strength. So the comparison to spider silk was actually appropriate. I also noticed that it’s from 2015, although it was still new to me and interesting.
- prmph 2y agoTo be fair tensile strength is more impressive and to me is the only true strength. Water has great compressive strength, and yet is it difficult to think of it as "strong".
- sk5t 2y agoWater being mostly incompressible is not the same as having high compressive strength. Liquid water makes for a poor tooth or structural column.
- prmph 2y agoThat's my point; think about it deeply.
- jmillikin 2y agoYou wrote "water has great compressive strength", sk5t directly (and correctly) refuted that claim. What is there to think about? Are you confusing "compressive strength" with compressibility?
- stormfather 2y agoI think his point is that things very rarely experience purely compressive forces. Just being compressed induces tension in other directions, like water being squished out between your clapping hands. So even though water has great compressive strength, in practice this isn't very useful.
- prmph 2y agoExactly. Many materials would have compressive strength easily, just by being relatively uncompressible. But most loads have a (troublesome) tensile component. Fundamentally, the ability of a rigid material to resist deformation (in the most general sense) is what is most important, and that requires tensile strength. See this comment elsewhere in this sub-thread that explains it probably better than I did: https://news.ycombinator.com/item?id=43904800 https://news.ycombinator.com/item?id=43904800
- prmph 2y agoLook up the Wikipedia definition [1] of compressive strength: > In mechanics, compressive strength (or compression strength) is the capacity of a material or structure to withstand loads tending to reduce size (compression). It is opposed to tensile strength which withstands loads tending to elongate, resisting tension (being pulled apart). Google search AI summary states: > Compressive strength is a material's capacity to resist forces that try to reduce its volume or cause deformation. To be fair, compressive strength is a complex measure. Compressibility is only one aspect of it. See this Encyclopedia Britannica article [2] about how compressive strength is tested. [1] https://en.wikipedia.org/wiki/Compressive_strength https://en.wikipedia.org/wiki/Compressive_strength [2] https://www.britannica.com/technology/compressive-strength-test https://www.britannica.com/technology/compressive-strength-t...
- blitzar 2y agoIt is useless until you are in a movie gun fight next to a pool / river. At that point jumping into the water is both life saving and cinematic with turbulent bullet trails follwing you in the water but falling just short of you.
- hwillis 2y agohttps://royalsocietypublishing.org/doi/10.1098/rsif.2014.1326 https://royalsocietypublishing.org/doi/10.1098/rsif.2014.132... > The tensile strength of discrete volumes of limpet tooth material measured using in situ atomic force microscopy was found to range from 3.0 to 6.5 GPa Also "compressive strength" is not really a thing, in that it's only a metric that is useful for practical applications. It's proportional to tensile strength, and unlike tensile strength it does not generalize well to things like modeling stress. Tensile strength is a much more fundamental quality than compressive strength. Strength of a material is force per area. In ideal terms it is measured over an infinitely short length; if you measure over a long distance then the sample is stretched and becomes thinner, changing the measurement. If you test on a shorter and shorter sample you get closer and closer to the ideal value. The same is not true for compressive strength tests. If you measure compressive strength by pressing on a very very thin disc of material it will just resist all force; it has effectively infinite strength. The actual failure mode of compression is always tensile strength in the radial direction, or buckling or something. You press the sample and it stretches sideways until it exceeds the sample's tensile strength in that direction. The shorter the sample is, the less it can expand radially and the stronger it appears to be. There is no "ideal" compressive strength, only useful test setups.
- hydrogen7800 2y ago>Also "compressive strength" is not really a thing. This is true, but neither is "tensile strength" really a thing for the same reason. A simple uni-axial tensile test is not really uni-axial, but a combination of orthogonal normal stresses that ultimately results in shear failure. I've heard it said that "all failure is shear failure", and I think that's true. When you look closely at the ductile fracture surface of a ruptured tensile specimen, the characteristic "cupping"[0] appearance consists of various surfaces at 45 degrees from the direction of the applied load. Principle shear stresses are always oriented 45 degrees from the principle normal stresses. [0]https://upload.wikimedia.org/wikipedia/commons/1/1b/DuctileFailure.jpg https://upload.wikimedia.org/wikipedia/commons/1/1b/DuctileF...
- hwillis 2y ago
- throwawee 2y agoThen the ideal armor must be sea snail teeth woven together with spider silk. This advancement could save millions in mythril and adamantine.
- AndrewOMartin 2y agoFinally the Druids get a viable endgame armour set!
- VladVladikoff 2y agoIf you’re into this kind of fantasy bioengineering I highly recommend reading The Tainted Cup and the sequel, A Drop of Corruption. And if anyone has read these, please tell me about any other books in this similar bioengineering genre, or even just highly unique fantasy worlds (I’m just so sick of books about dragons and boring magic).
- yreg 2y agoTress of the Emerald Sea is set on quite a unique world. The planet is covered by oceans of magical "spores" which react violently to water. For example the spores in the Emerald Sea, where the hero is from, instantly grow into massive vines that destroy everything in their path. That makes sailing rather dangerous. The story is whimsical, perhaps an adult fairy tale (or just a fairy tale?), so I don't know if it fits your taste.
- dekhn 2y agoA long time ago, Harry Harrison wrote a series (https://en.wikipedia.org/wiki/West_of_Eden https://en.wikipedia.org/wiki/West_of_Eden) where dinosaurs weren't wiped out, evolving for millions of years before primates showed up. The dinosaurs have a genetic-engineering based industry.
- doorpheus 2y agoTry the children of time it's a great scifi book about a spider civilization evolving with all the different tech they create
- lawlessone 2y agoso we need both to build a space elevator?
- andrewinardeer 2y agoTen years ago. Has there been any progress since then?
- Ancalagon 2y agoA startup has since been founded to commercially farm limpet teeth for use in aircraft. First viable airplane shell is anticipated to hit the market in 2250. /s
- 0x38B 2y agoFrom a 2022 study in Nature (1) where researchers grew limpet teeth: "The proof-of-concept presented in this study can be scaled up using made-to-measure chitin sheets and synthetic substitutes for limpet cell-conditioned media. Given that chitin is currently a waste by-product of the fishing industry⁴⁴, our approach would allow its repurposing into a novel composite material that could substitute for many existing synthetic materials that are manufactured in a polluting or unsustainable manner, and could help solve environmental challenges such as the ocean plastics crisis. Furthermore, as chitin is itself biodegradable, this bioinspired composite meets the key modern engineering challenge of sustainability. In short, this new material has the potential to be manufactured and disposed of without generating harmful waste products." 1: https://www.nature.com/articles/s41467-022-31139-0 https://www.nature.com/articles/s41467-022-31139-0
- GrantMoyer 2y agoThe Nature article's motivation seems not very well thought out to me, considering the fishing industry is among the most unsustainsbly and polluting industries on earth. It's even an especially large source of ocean plastics.
- _tom_ 2y ago[flagged]
- ahazred8ta 2y agoThe iron snail, Chrysomallon, inhabits undersea volcanic vents. It sticks to magnets. When probed with a diamond tip indentation test, it doesn't indent.
- goku12 2y agoWait! Are we talking about strength or hardness?
- LiamPowell 2y agoIf you're going to post ChatGPT output then at least bother to click on the links. If people wanted ChatGPT output, especially uncurated output, then they'd just go to ChatGPT themselves. I know you have not clicked on the links as the article that "reports tensile strengths up to ∼4.9 GPa" is just referencing the original article from 2015 to get that number.
- coolThingsFirst 2y agoDentist: I already found 5 cavities.
- s0rce 2y agoThey constantly grow new teeth so thats not a big deal.
- AdrianB1 2y agoThe comparison with kevlar and titanium is weird, as they don't compete in the same category of strength and they are not the strongest in their categories. "I heard kevlar is used in flak vests, so it must be strong" is not a scientific argument.
- theultdev 2y agoI believe they're comparing the tensile strength of the fibers of the tooth. Though the pop article is light on details.
- hwillis 2y agoKevlar is an appropriate comparison- it has one of the highest tensile strengths known. It is not just lightweight and tough, it is also extremely strong in absolute terms. The strongest kevlar is somewhere between as strong as this material and half as strong. Titanium is a pretty bad comparison. Its 10-20x weaker, and is also weaker than fiberglass, nylon, most steels, sapphire, many other types of metals and fibers...
- CRANQonX 2y agoDoesn't surprise me in the slightest - Have you ever tried grabbing one of those things off a rock>!?
- s0rce 2y agoThey don't hold on with their teeth, they use their foot.
- deleted 2y ago[deleted]
- putpoointheloo 2y ago[flagged]
- CGMthrowaway 2y agoThe strength quality of the mineral in question, goethite, is only good at nano scale (400-800nm). If the mineral fibers get bigger they are not as strong. Thus presents one of the challenges in replicating this for human use