Mintaka Posted February 21, 2011 Report Posted February 21, 2011 Is this a myth? Is it true that the material which makes a spider's web, gram for gram, is stronger than stee l? Surely if a length of steel was as thin as a spider's web filament, it would slice your finger off , no? Quote
Turtle Posted February 21, 2011 Report Posted February 21, 2011 Is this a myth? Is it true that the material which makes a spider's web, gram for gram, is stronger than stee l? Surely if a length of steel was as thin as a spider's web filament, it would slice your finger off , no? it is a specification of tensile strength that you heard of in relation to spider-silk vs. steel. are you concluding then that spider silk ought to slice off your finger too? using a filament of anything to "slice off" your finger applies a load other than end-to-end & that is a measure of compressive strength which can be quite different than tensile strength for the same material. i'm not sure how thin that steel wire can be drawn. :shrug: article: >> Ultimite tensile strength Spider silkProperties Spider silk is a remarkably strong material. Its tensile strength is comparable to that of high-grade steel (1500 MPa),[7][8] and about half as strong as aramid filaments, such as Twaron or Kevlar (3000 MPa).[9] Spider silk is about a fifth of the density of steel; a strand long enough to circle the Earth would weigh less than 500 grams (18 oz).[10] Spider silk is also especially ductile, able to stretch up to 1.4 times its relaxed length without breaking; this gives it a very high toughness (or work to fracture), which "equals that of commercial polyaramid (aromatic nylon) filaments, which themselves are benchmarks of modern polymer fibre technology".[11][12] It can hold its strength below −40 °C. The strongest known spider silk is produced by the species Darwin's bark spider (Caerostris darwini): "The toughness of forcibly silked fibers averages 350 MJ/m3, with some samples reaching 520 MJ/m3. ... Thus, C. darwini silk is more than twice as tough as any previously described silk, and over 10 times stronger than Kevlar."[13]... Quote
CraigD Posted February 22, 2011 Report Posted February 22, 2011 Some short answers to go with Turtle’s longer ones and links:Is it true that the material which makes a spider's web, gram for gram, is stronger than stee l?Yes. Using the wikipedia link in the previous post, gram for gram, spider silk is on average about 2.5 times as strong as cold drawn steel wire, the strongest kind. Spider silk varies widely in tensile strength, because a given spiders can produce many different kinds for different uses, so the average value used above is just that - an average. Some actual spider silk is stronger, some less strong. Spider species, weather conditions, and age of the silk effect it also. Surely if a length of steel was as thin as a spider's web filament, it would slice your finger off , no?No. Again taking the data from the preceding links, were it possible to draw steel as fine as spider silk, it would be about as strong as the strongest spider silk, so would be no more able to cut flesh. Ah, short answers are no fun! I don’t think it’s possible to draw steel nearly as thin as spider silk. As best I can tell (I couldn’t find an obvious “world records” page for it) the record for drawing single strands of steel is around 0.0001 m, compared to spider silk’s typical diameter of 0.000002 to 0.000004 m. The thinnest drawn metal wire, using gold, is nearly as thin as spider silk, 0.000005 m. Shaving multiple tangled short strands of steel, rather than pulling a single long one, so that many can break without the whole steel wool failing, can produce short fibers almost as thin, at about 0.0000065 m. Steel fibers this thin behave strangely. For example, they’re flammable, burning quickly, though not very hotly, even when wet, and can be kindled with a spark or and ordinary small battery. Quote
Mintaka Posted February 23, 2011 Author Report Posted February 23, 2011 once again I'm dumbstruck Craig. :rolleyes: Nature eh ? Whjo'd a thunk up such a miracle. We're so lucky just to be alive and see all this stuff. A short time just to watch spider's webs and marvel. Other night, I saw a David Attenburgh Sky tv thing, showed a type of spider hauling up big objects into its tree den by wrapping silk around it, then 'drawing' the silk thread back up into itself, raising the objects higher and higher. I didn't understand how the thread didn't snap, til now. Incredible. Stronger than Kevlar! Next we'll be seeing spiders weaving bullet proof vests for the army on production lines. Cheers! :) Some short answers to go with Turtle’s longer ones and links: Yes. Using the wikipedia link in the previous post, gram for gram, spider silk is on average about 2.5 times as strong as cold drawn steel wire, the strongest kind. Spider silk varies widely in tensile strength, because a given spiders can produce many different kinds for different uses, so the average value used above is just that - an average. Some actual spider silk is stronger, some less strong. Spider species, weather conditions, and age of the silk effect it also. No. Again taking the data from the preceding links, were it possible to draw steel as fine as spider silk, it would be about as strong as the strongest spider silk, so would be no more able to cut flesh. Ah, short answers are no fun! I don’t think it’s possible to draw steel nearly as thin as spider silk. As best I can tell (I couldn’t find an obvious “world records” page for it) the record for drawing single strands of steel is around 0.0001 m, compared to spider silk’s typical diameter of 0.000002 to 0.000004 m. The thinnest drawn metal wire, using gold, is nearly as thin as spider silk, 0.000005 m. Shaving multiple tangled short strands of steel, rather than pulling a single long one, so that many can break without the whole steel wool failing, can produce short fibers almost as thin, at about 0.0000065 m. Steel fibers this thin behave strangely. For example, they’re flammable, burning quickly, though not very hotly, even when wet, and can be kindled with a spark or and ordinary small battery. Quote
Mintaka Posted February 23, 2011 Author Report Posted February 23, 2011 once again I'm dumbstruck Craig. :rolleyes: Nature eh ? Whjo'd a thunk up such a miracle. We're so lucky just to be alive and see all this stuff. A short time just to watch spider's webs and marvel. Other night, I saw a David Attenburgh Sky tv thing, showed a type of spider hauling up big objects into its tree den by wrapping silk around it, then 'drawing' the silk thread back up into itself, raising the objects higher and higher. I didn't understand how the thread didn't snap, til now. Incredible. Stronger than Kevlar! Next we'll be seeing spiders weaving bullet proof vests for the army on production lines. Cheers! :) ps- Also incredible, that a silk thread stretching all the way around the planet would weigh less than 500 grams. Quote
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