3 ms·
To 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
by prmph 1y ago
To 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 1y agoWater being mostly incompressible is not the same as having high compressive strength. Liquid water makes for a poor tooth or structural column.
- prmph 1y agoThat's my point; think about it deeply.
- jmillikin 1y 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 1y 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 1y 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 1y 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...
- brennanpeterson 1y agoPlease tell me how to make a water prism to test compressive strength and deformation resistance. Water is an incompressible fluid, that is different. These are well understood terms in the field. Unfortunately, this illustrates the bounds of ai in subfields like materials: it confuses people.
- prmph 1y agoI'm not saying water meets the strict definition of a material with high compressive strength (it does meet some, since it resists forces that attempt to decrease its volume well). I am just using as an extreme example of the issues with the concept of compressive strength.
- thatcat 1y agolower the temperature
- jmillikin 1y agoNothing that you wrote here indicates you understand what is being discussed. Water has very low compressive strength, so low that it freely deforms under its own weight. You can observe this by pouring some water onto a table. This behavior is distinct from materials with high compressive strength, such as wood or steel. (I say "very low" instead of "zero" because surface tension could be considered a type of compressive strength at small scales, such as a single drop of water on a hydrophobic surface)
- cma 1y agoVery hard to force it to failure into permanent changes in shape.
- blitzar 1y 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.