Equal distance between points+finding support using Galapagos

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Permalink Reply by peter fotiadis on December 12, 2015 at 12:09am

Well ... now we are talking (AT LAST, he he).

Guide into the unknown: (alias T for Tensegrity, TX for X-truss tensegrity, TDT for double tetra tensegrity).

1. Tensegrity (= Tension + Integrity) is a freaky thing consisting from triangulated "modules" (i.e an assembly out of this, this and that) where the exterior edges ARE always under tension (= SS 304/316 cables OR nylon) and the interior ones MAY be under compression ( = steel, aluminum, wood, carbon) OR ... some of them ...may be under tension. Bastardized T trusses deviate a bit from theory ... but who cares? (not me anyway). T trusses have many variants (but as the greatest ever said: Less is More).

2. Large scale T for AEC is the art of pointless since it costs around the GNP of Nigeria. Here's some indicative components from a module of a multi adjustable TX system costing (the module) ~ the price of my Panigale (Google that):

The above is mailed to a friend who has MIT (yes, that MIT: the top dog) on sight ... therefor he needs some appropriate "credentials", he he.

3. The distance that separates the above with the demo TDT node provided is around 666.666 miles - but we don't care: we are after Art not some testimony to vanity.

4. On purpose I've used a smallish ring to give you a clear indication upon the constrain numero uno in truss design: CLASH matters.

5. You'll need:

(a) A decision related with the tensioners (classic Norseman + SS cables or nylon machined thingies?).

(b) A machinist who can do elementary stuff (like the adapters) and can weld this to that (the "ring" for instance). His abilities must be 1 in a scale of 100. If the fella has a computer (not a CRAY) and he knows what 3dPDF is (hmm) ... well ... use that way to communicate with him PRIOR designing anything: He must agree on the parts BEFORE the whole is attempted (as a design in GH or in some other app).  

(c) A carpenter with a wood lathe for the obvious. BTW: BEFORE doing any TDT attempt > ask the carpenter about the available wood strut sizes. Against popular belief DO NOT varnish the wood (use exterior alkyd/oil stains from some top maker like the notorious US company PPG).

http://www.ppgpaints.com/products/paints-stains-data-sheets

(d) Good quality cigars (and espresso) plus some classic music (ZZTop, PFloyd, Cure, Stones, U2 etc etc) during the assembly.

(e) Faith to the Dark Side (see my avatar).

May the Force (the dark option) be with you.

Permalink Reply by peter fotiadis on December 12, 2015 at 12:34am

BTW: If the "ring" is beefier and in order to skip the expensive Norseman tensioner (AND most importantly to "address" CLASH situations) you can use a variety of component combos for the purpose:

And the classic "basic" cable terminal:

Permalink Reply by Maria Ostroumova on December 12, 2015 at 5:55am

I'm about to understand how to make the joints you suggest, just thinking about alternative option for rings, as far as I understand those "pyramyd" rings are customized? 

And what about rectangular section of wooden elements, is it possible in this type of structure?

Permalink Reply by peter fotiadis on December 12, 2015 at 8:07am

Yes the rings are custom - what else?. These trusses are bespoke and no mass made system is available. But it's the simplest possible safe solution for a small project like yours that only has to support itself.

For a "bigger" one ... well ... that would be another animal and it would require another "beefier" variant of the system (PLUS FEA on anything not only the members):

PS: Rectangular wood sections are obviously entirely doable (BUT be aware of the finesse of the strut: putting a rectangular member in a lathe [tapered ends] it's rather out of question: thus you'll end up with straight members end to end - the so called elephant leg syndrome in our trade).

Permalink Reply by Igor on December 12, 2015 at 3:34am

Hi,Maria

What at you it didn't turn out with the Kangaroo? In my opinion it is optimum option for optimization of structure. Of course absolutely equal lengths of beams it won't turn out in a design of a free form, but it is possible to receive approximately equal lengths with the small admission. Tensegrity truss in a design for a concert seems to me doubtful from the point of view of stability and safety. It is difficult to calculate stability of a design which behaves itself by means of a body weight due to flexible links. Anyway when using the "budgetary" disposable design not to do without additional cable links.

It is optimization option with the Kangaroo (you need Kangaroo1 and Kangaroo2):

PS. Кстати, концерт будет посвящён Сергею Курёхину?

PPS. Для улучшения точности можно также поэкспериментировать с методом последовательных приближений при помощи плагина Anemone (рекурсивные действия).

Attachments:

• BeamsConstruction.gh, 31 KB

Permalink Reply by Maria Ostroumova on December 12, 2015 at 5:38am

Здравствуйте, Игорь! Да, это концерт в центре Курёхина, последний концерт перед полной реконструкцией театра) Главная проблема сейчас в том, чтобы обеспечить безопасность музыкантов на сцене(а также зрителей), при этом используя доступные средства. Я просто не понимаю, как сделать узлы такой жесткой версии безопасными, при этом, чтобы можно было смонтировать их в короткий срок... В случае с тенсегрити, по крайней мере, понятно, что она будет держаться засчет натяжения. У меня абсолютно нет уверенности в несущей способности фермы под потолком, на которую я сначала предполагала подвешивать эту "палочную" конструкцию. В общем, на мой взгляд, большой плюс тросовой фермы в том, что она сама себя держит, и можно поставить ее на пол, а подвесы использовать для дополнительной фиксации в пространстве. 

С длиной стержней я вроде справилась, да, с помощью Kangaroo)) Но конструкция потеряла что-то в своем очаровании, поэтому я решила, что нужны неодинаковые стержни. Но пока нет ясности с технологией, я не понимаю, какую методику использовать для моделирования.

Permalink Reply by Igor on December 12, 2015 at 6:05am

Предлагаю обсудить это посредством личного почтового ящика. Я отправил вам короткое сообщение. После вашего ответа будет возможность писать более развернутые письма.

Permalink Reply by peter fotiadis on December 12, 2015 at 4:35am

BTW: Most "fear" tensegrity because it's "unsafe" (or they believe so). But in fact the most expensive, bespoke, SAFE (nothing in this planet behaves better VS seismic forces) and WOW glazing systems these days ARE due to tensegrity systems (Google: planar glazing and the likes). And speaking about safe glazing systems ... hope that anyone knows what a collapse means in countries like US (MILLIONS as amends etc etc).

So  tensegrity is COMMON (but not very often as a "classic" truss due to cost or ignorance or inability to design 1:1 components) AND is NOT an alien thingy that landed on planet Earth to cause Armageddon.

For your scope AND having in mind WHAT actually means (in real-life) to make this truss from wooden beams (in real-life) ... well ... it;s kinda comparing a Honda C50 with a CBR RR Fireblade.

Anyway get the most suitable DIY variant TDT truss for your scope in STEP214 and the 3dPDF (as a "portable" sketch: for talking with some machinist or carpenter or some Allien just landed on Earth ).

 

Attachments:

• RUSSIA_DECORATIVE_DIY_DOUBLE_TETRA_TENSEGRITY2.stp, 1.2 MB
• RUSSIA-TENSEGRITY2-000.pdf, 696 KB

Permalink Reply by Maria Ostroumova on December 12, 2015 at 5:59am

I have just thought about those spring hooks! I think they are more avaliable here.

Permalink Reply by peter fotiadis on December 12, 2015 at 8:13am

You mean the snap shackle? If yes note that you'll need to machine threads (if not the right type is available locally).

See PDF (use the dynamic section capability available to the latest Readers - use the model tree thingy as well: isolate anything on a per object basis).

PS: For the floor fixing brackets Google: ball pivot join.

Permalink Reply by peter fotiadis on December 12, 2015 at 9:06am

PS: Other Kings or joints that "accidentally" are all German:

Clevis, Angle joint, Ball joint, Bolt, Rod end - mbo Osswald

mbo-Linking technology

Experience the great variety of VORMANN-products

PS: mini ball pivots could connect your initial "equal" wooden beams (instead of the Captain Hook "live-and-let-them-die" option, he he) ... but the problem is ... that require some bulletproof fixing policy (risky on smallish wood beans without a custom bracket: better safe than sorry).

Permalink Reply by Maria Ostroumova on December 12, 2015 at 6:24am

P.S. Dark side is a place I live in (staying at home in front of the screen for a week) ahaha

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