Bay 12 Games Forum
Dwarf Fortress => DF Gameplay Questions => Topic started by: Uristocrat on March 20, 2011, 03:20:35 pm
-
After doing this research (http://www.bay12forums.com/smf/index.php?topic=80022.0), someone suggested trying to look up the other important material values (http://df.magmawiki.com/index.php/Metal#Weapon_.26_Armor_Quality). The main problem is that about the only thing I can find for most materials is Mohs hardness and I don't know which (if any) of those things that's even related to, nor how to convert it to something useful to DF.
Does anyone know of good information sources for the strength of materials like these, or ways of calculating those important values from more readily available stuff? I have to believe that, at the very least, for architecturally important stones like marble/slate/etc., there ought to be some data out there somewhere.
-
Mind you, the problem isn't that I can't find lists of information, it's that I have no idea what converts to what, or which value I'm finding. There are plenty of lists out there with hardness data (http://en.wikipedia.org/wiki/Hardnesses_of_the_elements_%28data_page%29) and the Wolfram links I have in that research thread usually have Mohs hardness. It's not hard to find Young's modulus (http://en.wikipedia.org/wiki/Young%27s_modulus) either.
But even when I find conversion information (http://en.wikipedia.org/wiki/Pascal_%28unit%29), I still don't know how to match them up with the appropriate properties in Dwarf Fortress.
I took electrical engineering classes, not mechanical engineering, sorry :)
EDIT: Oh yeah, I *have* been reading up on material strength (http://en.wikipedia.org/wiki/Strength_of_materials). I'm assuming that DF ignores tensile strength entirely right now and that "impact" corresponds to compressive stress. Beyond that, I have a lot of reading to do....
-
Only compressive and tensile strength figures are used at the moment. Compressive is used for both compressive and impact figures, tensile is used for everything else.
I did some research on metals about a year or so back and was pretty much unable to find compressive figures, so currently even those figures are placeholder derived from tensile ones (ie. compressive figures for yield and fracture are currently just 3.5* the tensile figures, as per inorganic_metal). So the IRL tentile strength is the pivotal figure in current system.
The problem you'll encounter with non-metallic stuff is that while there may be relatively reliable conversions from hardness to tensile strangth for metals these don't really apply to other stuff. The current material system also does not recognize brittleness/toughness or fracture toughness, so that could and would cause some interesting results if you gave gems and certain types of rocks face values.
For example, diamonds are not only ridiculously hard but they also have extremely high tensile strength (estimated). Easily 100 GPa or more. As comparison, ingame adamantine is measily 5 GPa in tensile strength (ultimate). While diamond itself would not be a problem, obsidian would easily be rendered over the top since under the current mechancis the blades or whatnot made out of it would not shatter in high stress contact with less hard but way more tough material (like any metal).
If you really want to give some less placeholdery figures for various minerals, Wiki page for mohs hardness has table for comparison between mohs and vickers hardness. You should be able to find conversion tables or automatic converters for converting vickers hardness (HV) to ultimate tensile strength (ultimate strength is called fracture in raws), at least ones that apply to metals so you might will get some wierd results yeah. Also since most of these stuff you are looking at is quite brittle relatively, give them yield figure relatively close to the fracture figure if you are unable to find an exact figure for yield point. Or you might just make them perfectly brittle (yield is same as fracture in raw terms, such as on adamantine) though I don't know if that has much effect ingame.
http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
-
Only compressive and tensile strength figures are used at the moment. Compressive is used for both compressive and impact figures, tensile is used for everything else.
I did some research on metals about a year or so back and was pretty much unable to find compressive figures, so currently even those figures are placeholder derived from tensile ones (ie. compressive figures for yield and fracture are currently just 3.5* the tensile figures, as per inorganic_metal). So the IRL tentile strength is the pivotal figure in current system.
The problem you'll encounter with non-metallic stuff is that while there may be relatively reliable conversions from hardness to tensile strangth for metals these don't really apply to other stuff. The current material system also does not recognize brittleness/toughness or fracture toughness, so that could and would cause some interesting results if you gave gems and certain types of rocks face values.
For example, diamonds are not only ridiculously hard but they also have extremely high tensile strength (estimated). Easily 100 GPa or more. As comparison, ingame adamantine is measily 5 GPa in tensile strength (ultimate). While diamond itself would not be a problem, obsidian would easily be rendered over the top since under the current mechancis the blades or whatnot made out of it would not shatter in high stress contact with less hard but way more tough material (like any metal).
If you really want to give some less placeholdery figures for various minerals, Wiki page for mohs hardness has table for comparison between mohs and vickers hardness. You should be able to find conversion tables or automatic converters for converting vickers hardness (HV) to ultimate tensile strength (ultimate strength is called fracture in raws), at least ones that apply to metals so you might will get some wierd results yeah. Also since most of these stuff you are looking at is quite brittle relatively, give them yield figure relatively close to the fracture figure if you are unable to find an exact figure for yield point. Or you might just make them perfectly brittle (yield is same as fracture in raw terms, such as on adamantine) though I don't know if that has much effect ingame.
http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness
I saw that on Wikipedia. I'm not sure that one can convert Mohs hardness into a sensible value because it's ordinal. So there's no real relationship between the hardness and other values. I'm not completely sure, but you *might* be able to extrapolate a constant slope between 1-2, 2-3, etc. and be able to convert that to a meaningful value, but I'm not too sure.
-
I saw that on Wikipedia. I'm not sure that one can convert Mohs hardness into a sensible value because it's ordinal. So there's no real relationship between the hardness and other values. I'm not completely sure, but you *might* be able to extrapolate a constant slope between 1-2, 2-3, etc. and be able to convert that to a meaningful value, but I'm not too sure.
I'm not sure if making a slope is worth the effort. Basically I was just advicing you to take very rough guesses and be satisfied with the end result, which would still be better than the current placeholders. I mean, not only is mohs scale ordinal and unreliable for our purposes, converting hardness to tensile strength is bit silly for the scale of minerals we have here. Metals seem to have relatively consistant relation between hardness and strength, but things like volcanic glass are right out.
To really find accurate figures you'd need to dig up the explict tensile strength of each of these minerals, and I doubt you will manage that without specialist literature (or perhaps not even then). And even then, the current material system doesn't really give us all the tools to make materials come alive and behaves as they really would.
-
To really find accurate figures you'd need to dig up the explict tensile strength of each of these minerals, and I doubt you will manage that without specialist literature (or perhaps not even then). And even then, the current material system doesn't really give us all the tools to make materials come alive and behaves as they really would.
You might be surprised. I grant that it's thanks to Google book search, but I've found a lot of weird, but helpful results online. Problem is that I don't know exactly what to search for, because it seems like DF is using its own names for things.
For example, to get density, I almost always had to look up specific gravity and convert it. So much so that I got some weird, experimental feature to enable itself and it started saying that Google's "best guess" for the specific gravity of some material was X, based on N sites and asked me to confirm (the value it gave was very reasonable based on the ranges I saw, too).
If I knew how to convert, say, Young's Modulus into something DF uses, then we might be able to get somewhere (but it probably only works well for metals, huh?).
-
If I knew how to convert, say, Young's Modulus into something DF uses, then we might be able to get somewhere (but it probably only works well for metals, huh?).
Young's Modulus just measures how material behaves under stress while it still hasn't crossed the yield point. I doesn't directly have relation to yield points or ultimate strength AFAIK. If you knew the exact test condition you might get something out of that.
You might be surprised. I grant that it's thanks to Google book search, but I've found a lot of weird, but helpful results online. Problem is that I don't know exactly what to search for, because it seems like DF is using its own names for things.
Also try Google Scholar. You just might hit into gold there. http://scholar.google.com/
-
Also try Google Scholar. You just might hit into gold there. http://scholar.google.com/
More like paywalls :( Wish I was still at university, then I might not see so many links that say, "Here's the abstract. Purchase the full paper (which might not even have the right information) for just $39.95."