Talk:Space frame

Latest comment: 3 years ago by Greglocock in topic Name

text under picture: "Simplified space frame roof with the nearest unit tetrahedron highlighted in blue"

it is not a tetrahedron that is highlighted, it's a half octahedron

audi?

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what about the audi space frame concept? —Preceding unsigned comment added by 212.183.115.89 (talk) 13:11, 30 September 2007 (UTC)Reply

Question about a link

http://www.omion.gr/ appears to belong to an engineer or an architect that works with these structures. Should this be moved to the informational link section or simply removed? I don't speak Greek, so perhaps this page contains more information than it appears. --Gr gal1993 (talk) 20:49, 19 December 2007 (UTC)Reply

The links have been alphabetized for easier reading. 5 February 2009 —Preceding unsigned comment added by 69.214.1.186 (talk) 18:58, 5 February 2009 (UTC)Reply

Auto space frames

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The article presently claims that the Honda NSX was the first vehicle to use a space frame. However, the NSX actually had an aluminium monocoque frame, as the Wikipedia NSX article attests. Also, companies like Lotus and TVR have been making tube-frame, if not actual space-frame, cars since the 1940s and 1950s. I'm editing the article to reflect this. --Mpa (talk) 01:15, 13 January 2011 (UTC)Reply

The first spaceframe car was the Lotus VIII of 1953. There were many, many tube frame cars before this, including several by Lotus, but this was the first to be truly designed as a space frame, rather than a ladder with additional members added. Colin Chapman was assisted in it by aircraft designers. Several other cars, such as the Stout Scarab and anything involving Bucky Fuller get labelled as "space frames", but weren't strictly so. Cars don't really need spaceframes and placing their structural members where needed is difficult to combine with driver access and visibility. So they're still mostly a ladder or platform, with bending moments into it (thus not a space frame), and some outriggers above. Andy Dingley (talk) 10:09, 29 September 2018 (UTC)Reply

Two forms?

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It seems like there's two forms of this, one as a square tiling, and one with a triangular tiling. Are they both considerd "space frames"? Both are contained within the Tetrahedral-octahedral honeycomb. The first splits the octahedrons into half as square pyramids. The second has the octahedral volumes triangle-face up, so the surface triangles alternate between octahedral/tetrahedral volums. In the second case, these can be stacked in two different ways, as oct-oct/tet-tet or oct-tet face connections. Tom Ruen (talk) 19:35, 1 December 2011 (UTC)Reply

 
Triangular tiling boundary
(Red octahedra, yellow tetrahedra)
 
Square tiling boundary

Structural geometry

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An editor has redirected Structural geometry here without merging any of the materials to be found there. Perhaps someone familiar with the field could look over what's below and decide if any of it adds to Space frame? Sorry to take up all this room on the talk page but it does seem best way of ensuring the stuff is properly available. Chiswick Chap (talk) 19:12, 5 December 2012 (UTC)Reply

 
"An isotropic compression structure"

!In structural engineering, structural geometries often obtain a high degree of strength from a minimal amount of material[1], being efficient, lightweight, and as strong as their geometries could allow given the various contexts. There is no single strongest structure, as there are many different types of strength. Some truss like structures present the optimum geometries for resisting cantilever stresses, remaining rigid by reducing bending moments, resisting deformation under a combination of compression, tension and shear[2]. Other structures present the most efficient geometry for resisting purely compressive stresses, distributing loads efficiently with the shortest paths to minimize lateral buckling[3]. Still others represent the strongest geometries for resisting purely tension, carrying the force in a direct route so as not to amplify the stress.

Also there are singular shapes which hold their form in circumstances where pressures are exerted at different points, i.e. catenary curves and catenary domes[4], spherical domes, and pyramids and triangles.

Before the strongest structure for a particular circumstance can be established, it is necessary to determine the kinds of stresses the structure must resist.

Tension

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Stress amplification

The most efficient geometry for carrying solely tensile stress is a straight line parallel with the direction of the force, such a steel cable. These are extensively used in suspension bridges, which are popular as tension elements typically require significantly less material than compression elements which must resist buckling. If a cable were to branch out at various angles, the stress carried by the original cable would be amplified.

Far more complicated geometries arise when loads are carried on a cable running perpendicularly to the direction of the force. The catenary curve is the optimum geometry for carrying such loads if they are uniform at all points, both in compression (see arch) and in tension. Also when such loads must be carried at various angles, over a large sheet or mesh, the optimum geometry becomes very complex. Frei Otto did pioneering work with soap bubble films, which spread between points to find the minimum possible surface area, and when the geometry is translated into a tension structure, the least amount of material may be used to cover a specific area.[5]

 
Alternated cubic tiling, similar to the octet-truss

Cantilever - Tension and Compression

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The strongest known truss for resisting tension and compression is an octet-truss, but only in terms of a repeating isotropic geometry, and this structure is used extensively with cantilever and long spanning roof applications. The structure is composed of a repeating tessellation of octahedrons and tetrahedrons, which are made up of triangular faces.[6] The triangle is the best shape for remaining rigid as it does not give in to geometric distortion without changing the length of one of its edges; in contrast to squares which may be easily distorted into various parallelograms. The triangle does the best job of minimizing bending moments[7].

Compression

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A tessellation of hexagons is the strongest isotropic geometry when considering only two dimensions.[8]

Frei Otto, again, did some pioneering work with tree like branching structures. A thick column would branch into more slender beams, into again more slender beams, which would concentrate compressive forces into the central column with each beam resisting buckling due to their short individual lengths. This kind of tree like branching structure represents the optimum, anisotropic, structural geometry.

Individual Circumstances

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File:Bone chair.jpg
A drawing of Joris Larmaan's 'Bone Chair'

There are many factors which must be taken into account when finding the optimum geometry for a structural support system. While a catenary dome may be the best hollow form for resisting the forces of gravity, a spherical dome is the best hollow form for resisting uniform forces in all directions; this is the reason for their wide spread use as windows on submarines, and in space.[9]

A truly optimized structural geometry in many circumstances is likely to be highly complex, and require the use of FEM technology (finite element method). An interesting example in the design world is Joris Laarman's bone chair, which was developed using FEM (with CAD software developed by Adam Opel) and a genetic algorithm[10].


See also

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References


Stretch-dominated octet frame

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This and this article refer to a special case, the stretch-dominated octet frame, as providing the highest known strength/weight ratio. Besides, it's an interesting read. LeadSongDog come howl! 20:11, 9 July 2014 (UTC)Reply

Parashells

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Since when are parashells space frames? Andy Dingley (talk) 00:10, 17 November 2015 (UTC)Reply

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Is Seattle's Safeco Plaza the first "Vierendeel space frame"?

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The Safeco Plaza (Seattle) article currently claims that the building is:

...the first skyscraper in the world to feature a Vierendeel space frame.(citation: Space frame at Emporis)

Note that neither "Vierendeel" nor "space frame" link here. Should they? Is the claim correct? -- RobLa (talk) 01:25, 29 September 2018 (UTC)Reply

Name

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Okay, good, but people are going to want to know "why space frame?" Does space refer to the advanced, futuristic nature of the design, or does it refer to its three dimensional form? Was this the original term coined from the time it was first invented, or did space frame only become the term decades later when they started using truss structures like this in the exciting new designs for space stations and space ships, etc? Some more detail about this would be nice. Also, the section on aircraft is utterly insufficient. It makes it sound like only two obscure Australian aircraft have ever used triangulated truss fuselage frames, but that was a standard construction method before WWII. The Hawker Hurricane, the Savoia-Marchetti SM.79, the Yak fighter family, the Fi 156, the SM.81, the Kawanishi E7K...those are just the ones I know of right off the top of my head. This will include pretty much any plane that was built with a wood and fabric fuselage after the days of wooden frames, and before the semi-monocoque fuselage came in. There were plenty of pre-war aircraft that had both metal skinning and triangulated truss framework. Now, I am not 100% sure such framing counts as "space frame" (sure appears to be the same), but I do know that they are structurally identical to the two Australian aircraft listed in the text, so either they all have space frames, or none of them do, and those are wrongly included.

Hurricane cutaway, showing the metal frame surrounded by fabric covered wooden formers that gave the fuselage its aerodynamic shape (sheet metal over the front half) http://www.fiddlersgreen.net/aircraft/Hawker-Hurricane/IMAGES/Hawker-Hurricane-Cutaway.jpg Here's a Hurricane without its skin: http://www.williammaloney.com/Aviation/VintageWingsOfCanada/HawkerHurricane/pages/30HurricaneFuselageFrame.htm If that's not a space frame, then I'm missing something. The SM.79 https://i.imgur.com/5duj77f.gif (Maybe just a truss, if there's a difference) Idumea47b (talk) 06:31, 5 December 2020 (UTC)Reply

I wouldn't call the Hurricane fuselage a spaceframe, it is bulkhead and stringer, not triangulated axially stressed members. Whether that is wiki's definition is a separate point altogether. Greglocock (talk) 10:56, 5 December 2020 (UTC)Reply