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We don't like building pressure structures out of brittle materials, because of the potential for rapid catastrophic failure. However, it occured to me that soda and beer bottles are often made from glass and sustain internal pressures of up to 2.5bar(g). This is acceptable because the bottles are designed to keep wall stress beneath the 'critical stress intensity' for any realistic defect size.
The formula is:
Max acceptable stress = Kic/((pi x c)^0.5)
Kic is stress intensity factor in MPa.m^0.5; c = crack diameter (m).
If maximum allowable stress is exceeded for a known defect size, c, then cracks propagate catastrophically.
For soda glass, Kic is 0.7 - 0.8. For non-reinforced concrete, it is 0.2. For granite, it is 1.7 - 3. For slate, it is 2.5 (against the grain). For reinforced concrete, it is 10-15.
This suggests that we could build pressurised, ceramic structures on Mars, provided we control carefully the wall thickness and the size of defects. If we assuming masonry walls consisting of native stone cemented together with wet regolith, Kic can probably be taken to be similar to concrete. The stones will tend to interupt formation of cracks, limiting the size of defects to no more than 10cm. Solving the equation gives an allowable tensile stress of 350KPa. Lets say we build a 10m diameter spherical structure that is cast from this material. Internal pressure is 50KPa. The minimum wall thickness can be estimated using the spherical pressure vessel equation:
t = PR/2xsigma = (50KPa x 5)/(2 x 350KPa) = 250/700 = 0.357m (1').
Increasing the thickness of the walls would add safety factor. A 1m thick wall would need require a defect 1.27m long to cause catastrophic failure. This is highly unlikely and can be ruled out by overpressure testing.
Last edited by Calliban (2022-10-18 10:46:12)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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There are also Glass-Ceramics now used in underground structures, subterranean construction, Glass-ceramics are another area to explore now used biological applications due to their unique interaction, or lack thereof, with human body tissue and having properties of glasses with benefits of ceramics. It can become a container, they are also used in storage of foods. You see them in Cooktops, Smartphone screens and there is application in Biomedical field and Infrared heat, an example of bioinert materials are alumina (Al2O3) and zirconia (ZrO2) bone loss and other illness might trouble the Martian colonist. Glass Ceramic is used as cookware on Earth a heat-resistant, glass-ceramic material with a thermal shock resistance, large soup bowls, casserole dish etc.
Glass is used to brighten places or reproduce lighting in normally dark cold places.
You can still have 'privacy' with frosted glass.
'Glass-ceramics consisting of various oxide crystals in a matrix of siliceous residual glass offer properties not available with more common silicate crystals.'
https://www.sciencedirect.com/topics/ch … ss-ceramic
Difference Between Glass and Ceramics
https://askanydifference.com/difference … -ceramics/
Properties, Processing and Applications
https://matmatch.com/learn/material/glass-ceramics
Caves, Tunnels and Bunkers: Seeking Seclusion in Subterranean Structures
https://architizer.com/blog/inspiration … terranean/
'Dig up history to discover longstanding traditions of underground architecture.'
frosted-glass mirrors inject polish to the subterranean space.
https://www.azuremagazine.com/article/a … acilities/
A structure such as a globe with moss and water inside, the vivarium hab?
the bottle garden, the iminiature home terrarium, vivarium may be small enough to sit on a desk or table, such as a terrarium or an aquarium, or may be a very large structure, a feature of gardens and research on Earth and possibly outdoors.
When used for sealing, some glass-ceramics do not require brazing but can withstand brazing temperatures up to 700 °C
http://www.elantechnology.com/glass/gla … omponents/
Last edited by Mars_B4_Moon (2022-10-18 12:32:58)
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I carried out a comparison of embodied energy between mars cement and mortar and a cast iron pressure vessel. The application is a roughly spherical, 10m diameter structure pressurised to 0.5bar.
A rough cast iron has a Kic of about 6. A 2.5mm thick pressure shell, with a tensile stress of 50MPa, has a critical crack length of 3.8cm (1.5"). Assuming a density of 8000kg/m3 and an embodied energy of 30MJ/kg (typical of fresh steel on Earth), embodied energy works out to be 600MJ/M3.
The masonry walls would have thickness about 1m. They would be constructed from mortar bonded stone, with proportions of 20% mortar, 80% stone. Water will be 1/3rd of the volume of the mortar. So about 67 litres of water are needed for every cubic metre of masonry. I worked out a while back that water would have embodied energy of about 1MJ/kg on Mars. Given that rock and sieved regolith are virtually free, the embodied energy of the masonry would be <100MJ/m2. So masonry looks considerably better than iron from an embodied energy viewpoint.
The more I think about it though, tensile masonry pressure structures just don't make sense. The compressive strength of the masonry would be at least several MPa. So it makes more sense to construct thinner walls and heap overburden over the structure to vector the product of pressure and gravity forces such that all forces are absorbed by a mixture of compression and sheering strength. Buttress walls could also be used to exert horizontal counter pressure onto pressurised walls. The walls themselves should be slightly concave when viewed from the outside. For a surface structure, I think we woukd want at least twice as much overburden as needed to balance vertical pressure. If overburden has a density of 2500kg/m3, that implies a layer at least 10m thick. If we were building underground, the layer woukd only need by 5m thick. And we wouldn't need buttress walls, because the soil woukd provide back pressure. Building structures underground is a far more efficient solution on Mars that attempting to build them above ground.
In conclusion: Tensile masonry structures (the topic of this thread) represent a poor allocation of resources, because of the huge required thickness of walls. Underground masonry structures will beat just about any tensile surface structure, made from any material, on the basis of embodied energy per unit volume. So, if you are planning on emigrating to Mars, be prepared for an underground existence. Huge, transparent, tensile domes, look really good in movies. But they woukd be an expensive extravegance on Mars.
Last edited by Calliban (2022-10-18 13:03:24)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Might also go in the architecture design threads
Pottery Through History
https://www.worldhistory.org/collection … h-history/
The future of building: Are bioceramic dome homes the answer to resilient and affordable housing?
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I seen more news on Ceramic and building parts and structure
some links on what could be useful in a future Mars including simple art craft for items inside vessels.
Flexible Ceramic Aerogel Eyed for High-Temperature Applications
https://www.designnews.com/materials-as … plications
Now a research team led by engineers at UCLA has come up with a new solution for this task in an extremely light, very durable ceramic aerogel
3D Printed Furniture: 12 Designs That Explore Digital Craftsmanship
https://www.archdaily.com/996143/3d-pri … normal-tag
Missoula gallery opens ceramics gallery called Radius Clayworks
https://missoulian.com/entertainment/ar … 8f51c.html
What can you make with clay?
The Pottery Fair in Marratxi opens this Saturday
https://www.majorcadailybulletin.com/ho … urday.html
Preparation and characterization of hollow glass microsphere ceramics and silica aerogel/hollow glass microsphere ceramics having low density and low thermal conductivity
https://www.sciencedirect.com/science/a … 8820311002
Porous Glasses from Aerogels : from Organic Liquid to Mineral Materials
https://www.researchgate.net/publicatio … _Materials
Researchers create ultra-lightweight ceramic material that withstands extreme temperatures
https://phys.org/news/2019-02-ultra-lig … tures.html
Polymer derived ceramic aerogels
https://www.sciencedirect.com/science/a … 8621000395
Aerogels are unique porous solids having exceptional low relative density together with high specific surface area, making them very attractive materials for scientific research and industrial applications. Polymer derived ceramic aerogels are a new class of materials obtained through the pyrolysis of sol-gel/preceramic polymers.
Last edited by Mars_B4_Moon (2023-03-06 10:17:59)
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