Steve Jackson Games Forums (http://forums.sjgames.com/index.php)
-   GURPS (http://forums.sjgames.com/forumdisplay.php?f=13)
-   -   [Spaceships] Nanocomposite and structural materials (http://forums.sjgames.com/showthread.php?t=161120)

 Agemegos 12-16-2018 07:09 PM

[Spaceships] Nanocomposite and structural materials

I'm doing a bit of modelling of the engineering requirements of space habitats with spin gravity (for FLAT BLACK, where there is no synthetic gravity). In particular, I'm investigating how thick (and therefore massive) you have to make the hull of a cylinder spinning on its axis to support its own mass and that of a load (of armour, habitat, radiation shielding &c.) against the centrifugal effect of their inertia. It turns out (unsurprisingly) that the necessary thickness (and therefore mass and cost) of the structural hull depends strongly on the density and tensile strength of the structural material. I figure that:
t = r(P₁ + a₁λ)/(σ - ra₁ρ)
where
t = minimum thickness of the structural hull
P₁ = air pressure at the deck level
a₁ = centripetal acceleration at the deck level
λ = areic mass of the load (armour, shielding, habitat fittings, landscaping etc.)
r = radius of the cylinder
σ = tensile strength of the hull material (safe limit)
ρ = density of the hull material
I can find figures for the strength and density of some of the materials mentioned in GURPS Spaceships, such as mild steel and high-tensile steel, high-strength aluminium alloy, and titanium. Also, for polyester reinforced with glass fibre (a surprisingly good material for the purpose at TL7), epoxy reinforced with aramid fibre, epoxy reinforced with graphite fibre, diamond, cubic boron nitride, and carbon nanotubes (buckytubes). But there are some posited futuristic materials mentioned in Spaceships of which the identities are artfully vague, and for which figures are supplied implying their relative effectiveness as armour but not their actual density and tensile strength: metallic laminate (TL8), advanced metallic laminate (TL9), nanocomposite (TL10), space-adapted wood, living tissue, living bioplastic (TL10), exotic laminate.

Armour materials might not be the same as structural materials, of course.

Can anyone suggest what structural materials might correspond to the armour materials listed in Spaceships and what their densities and tensile strengths might be? Since FLAT BLACK is TL10 I'm most interested in what might correspond to nanocomposite.

 Agemegos 12-16-2018 08:11 PM

Re: [Spaceships] Nanocomposite and structural materials

I built a little calculator based on this work. It's an Excel workbook with no macros.

Just at the moment the list of possible building materials is a bit incomplete and some of the values for strength are questionable. But I put it on Dropbox for review and personal use anyway.

https://www.dropbox.com/s/7iilf35hdx...ator.xlsx?dl=0

 doctorevilbrain 12-16-2018 08:53 PM

Re: [Spaceships] Nanocomposite and structural materials

For some reason the words glass fibre reinforced polymer cover the number 1550.

 Agemegos 12-16-2018 09:06 PM

Re: [Spaceships] Nanocomposite and structural materials

Quote:
 Originally Posted by doctorevilbrain (Post 2229116) For some reason the words glass fibre reinforced polymer cover the number 1550.
The link leads you to a browser page that shows a version of the sheet that is suitable only for giving an impression. It can't actually be used.

Click on "open with" in the menu bar on the page and select "MicroSoft Excel online" or "MicroSoft Excel " (if you have it installed). Or click on the more menu "" in the top right and select "download".

 scc 12-16-2018 10:11 PM

Re: [Spaceships] Nanocomposite and structural materials

This is already covered in Spaceships on page 30

 The_Ryujin 12-16-2018 10:25 PM

Re: [Spaceships] Nanocomposite and structural materials

"Manocomposite" is kind of a catch all term in GURPS for different types of material that's the next step up from modern and next gen metal-matrix composites.

The main types covered are titanium nanocomposite, polymer nanocomposite, advanced polymer nanocomposite , ceramic nanocomposite (not sure if this would make a great building material since it's pretty brittle), and advanced nano-laminate.

Density is pretty easy to figure for these material.

Titanium Nanocomposite: 4g/cc.
Polymar Nanocomposite: 1.5g/cc.
Ceramic Nanocomposite: 3.19g/cc.

Tensile strength on the other hand... isn't as so clear cut since GURPS doesn't really go into this aspect of armor materials in detail and it doesn't help that outside of some very early experimental examples, a lot of these materials are currently hypothetical. However there is at lest some correlation between it and how good a material is at stopping bullets I can guessitmate titanium nanocomposite as having a tensile strength of at lest around 1,400 mega parcels, give or take (though given that there would probably be a ton of different types for different jobs this number is bound to differ a bit for structural material vs armor ones). The other examples are bit trickier to figure out thought IMHO titanium nanocompsite is probably the best example.

One ton (metric) of titanium nanocompsite costs (at TL10) \$132,277.20.

One square meter of it one centimeter thick weighs 10.2kg and has a DR of 69.

Hope this was at lest some help.

 Agemegos 12-16-2018 10:47 PM

Re: [Spaceships] Nanocomposite and structural materials

Quote:
 Originally Posted by Agemegos (Post 2229098) Can anyone suggest what structural materials might correspond to the armour materials listed in Spaceships and what their densities and tensile strengths might be? Since FLAT BLACK is TL10 I'm most interested in what might correspond to nanocomposite.
Quote:
 Originally Posted by scc (Post 2229121) This is already covered in Spaceships on page 30
With all due respect: it is not. Even on page 30, Spaceships does not identify structural materials corresponding to those armour materials, nor name the armour materials specifically, nor list the density or tensile strength of any material.

 Agemegos 12-16-2018 10:53 PM

Re: [Spaceships] Nanocomposite and structural materials

Quote:
 Originally Posted by The_Ryujin (Post 2229122) One ton (metric) of titanium nanocompsite costs (at TL10) \$132,277.20. One square meter of it one centimeter thick weighs 10.2kg and has a DR of 69. Hope this was at lest some help.
Thank you. Density figures get me halfway there; names of specific materials may help me find at least speculative values for tensile strength.

 The_Ryujin 12-16-2018 11:29 PM

Re: [Spaceships] Nanocomposite and structural materials

Quote:
 Originally Posted by Agemegos (Post 2229125) Thank you. Density figures get me halfway there; names of specific materials may help me find at least speculative values for tensile strength.
No problem man, this kinda of stuff is pretty much by bread and butter heh. Your Flat Back setting is pretty kick-awesome so I got no issues giving what assistance I can.

Pyramids 3-86 Cutting Edge and 3-96 Tech and Toys IV both have an articles written by David Pulver that have a lot of info on advanced armor material so you might want to check them out if you can.

 scc 12-16-2018 11:55 PM

Re: [Spaceships] Nanocomposite and structural materials

Quote:
 Originally Posted by Agemegos (Post 2229124) With all due respect: it is not. Even on page 30, Spaceships does not identify structural materials corresponding to those armour materials, nor name the armour materials specifically, nor list the density or tensile strength of any material.
For starters that's the best your going to get, but beyond that the answer doesn't really exist. Structural weight is included in the Control Room system, not the individual systems. Further more given that the largest ships is only 700 yards long and I'm pretty sure that we already build bigger ships is very plausible.

All times are GMT -6. The time now is 08:04 AM.