Stuff at the End (last one!)

Stuff at the End (last one!)

Original Design Document dated 25th July 1998

Fractal Bucky Tube

==================

DRAFT VERSION ie still full of holes

Contents

--------

Introduction

Requirements

Design

Design Notes

Properties

Formats

Extras

Applications

Conclusion

Contact

Introduction

------------

1) The following attempts to describe a design for a material/structure with useful

properties in a range of applications.

2) This document is in plain text to ensure ease of reading on any platform. As

such, it is not very pretty. I apologise for any detriment the presentation has on

the content. (Especially note the two dimensional nature of the diagrams, which

hides some of the complexity in the three dimensional equivalent).

3) This document assumes an established, but not necessarily mature, molecular

manufacturing technology is in existence. The material described is not complex,

but is probably beyond current or imminent manufacturing ability.

4) As I am not a chemist, physicist, or molecular biologist, what I am suggesting

may not be feasible, or may likely be a sub-optimal solution. It will also be

extremely superficial and lacking in detailed analysis. My apologies.

5) The concepts outlined below may merely be repetition or variation on an existing

design. If so, please feel free to gloss over them.

I was nearly tempted to avoid sending this to you at all, as the idea is so obvious

as to be almost self-evident.

6) If you find some useful elements, please feel free to use them in any way you

wish. My only request is that you keep me informed of their use.

Requirements

------------

Design a material with a large strength to weight ratio ie

a) high tensile, compressive, bending and torsional stiffness

b) relatively low mass

Design

------

The following would be much easier to visualise given one or more pictures or a

VRML 3D model. However I lack the skill to create either easily, so please excuse

the awkwardness of the description.

1) Imagine fifteen capped single walled carbon buckytubes T1 of width W1 length L1

(see Design Notes below)

2) Imagine three more capped buckytubes T2 of width W1 length L1*4

3) Place the T2 buckytubes parallel to each other perpendicular to and on the

vertices of an imaginary equilateral triangle with sides L1*cos(30) ie approx

L1*0.866 (one of the tubes protrudes by half L1 more than the others)

4) Place the T1 buckytubes between the T2 buckytubes, five to each side, at a 60

degree angle, forming four equilateral triangles between each of the three pairs of

T2 buckytubes.

One of the sides would look vaguely like this:

____________

/\ /\ /

/ \ / \ /

/____\/____\/

This would form a structure vaguely similar to that used in the beams of cranes

where each strut is circular steel and the joints between struts are welded

together.

At the points where the struts join, ensure that the minimum radius of curvature is

not less than that of a cross-section of the original buckytubes, otherwise these

will be weaker than the struts themselves. (ie round off the 60 degree angle joins

to make sweeping curves)

5) Deem the width of this structure W2 and the length L2

6) Now take 4 and a half of these...

One of the sides would look vaguely like this:

______________________________________________________

/\ /\ /\ /\ /\ /\ /\ /\ /\ /

/ \ / \ / \ / \ / \ / \ / \ / \ / \ /

/____\/____\/____\/____\/____\/____\/____\/____\/____\/

/\ /\ /\ /\ /\ /\ /\ /

/ \ / \ / \ / \ / \ / \ / \ /

/____\/ \/____\ /____\/ \/____\ /____\/

/\ / \ /\ /\ / \ /\ /\ /

/ \ / \ / \ / \ / \ / \ / \ /

/____\/__________\/____\/____\/__________\/____\/____\/

/\ /\ /\ /\ /\ /\ /\ /\ /\ /

/ \ / \ / \ / \ / \ / \ / \ / \ / \ /

/____\/____\/____\/____\/____\/____\/____\/____\/____\/

In three dimensions it is actually more complicated than this, and requires using

triangles with their corner cut off to avoid more than one cross strut competing

for the same spot on a lateral strut. However this is rather difficult to draw

without familiarity with a 3D modeling program. However, this is an attempt to

show the end view of the three dimensional structure outlined so far.

______

/\ /\

/ \ / \

/____\/____\

/\ /\ /\

/ \ / \ / \

/____\/ \/____\

/\ / \ /\

/ \ / \ / \

/____\/__________\/____\

\ /\ /\ /\ /

\ / \ / \ / \ /

\/____\/____\/____\/

Also, the end planes of the triangular tube in three dimensions are not parallel as

the above diagrams in two dimensions might suggest.

7) Repeat the above steps several times, at each stage taking the triangular tubes

produced and using them as struts in the larger version.

From this description, the term "Fractal Buckytubes" should be self-evident.

Design Notes

------------

1) If it is assumed that the original buckytubes have a diameter of 1.3 nanometers

and a length of 5 nanometers, and that this constitutes level 1, with levels 2 and

3 as suggested by the diagrams above (which are not quite to scale), then each

level is 4 times the linear size of the previous level (except 2 which is twice the

size of level 1) eg

Level Length Unit (Occupied Volume) / (Effective Volume) Ratio

(Estimated)

1 5 nanometers 0.5

2 20 0.64

3 80 0.4

4 320 0.26

5 1.28 micrometers 0.16

10 1.31 millimeters 0.017

15 1.34 meters 0.0018 ( approximately one in 560)

These values are examples only and not meant to be definitive.

2) The selection of an appropriate value for W1 will depend on finding an

appropriate value for the bonding angle tension. A good starting point would be a

"standard" buckytube, ie a C60 buckyball, cut in half, separated and connected by a

buckytube the same diameter as the buckyball.

3) The selection of an appropriate value for L1 will depend on the relative

strength to weight ratio required

a) shorter L1 will give higher strength at the cost of more mass

b) longer L1 will have less mass but also less strength

The value chosen will depend on the application

4) During construction, the caps on the end of each of the component buckytubes

would need to be opened to allow joining ie the caps are merely to ensure the

buckytubes remain stable between construction and assembly into a larger structure.

Properties

----------

1) high tensile, compressive and bending stiffness (as far as tensile strength is

concerned, presumably not as strong as pure buckytubes which are estimated to be up

to 150 times stronger than steel, but still strong enough for many applications)

2) relatively low mass eg approximately 500 times lighter than solid crystal

carbon (eg diamond)

3) partially transparent eg even if each atom appears black, the material would be

approximately 500 times "less black". Using the already existing example of

diamond as being quite transparent in crystal form, the material would possibly be

even more transparent. (As I am not a chemist, this is pure conjecture)

The graininess of the transparency is dependent on the largest scale used ie it

would be possible to continue constructing the material after any desired level

using the same scale components.

Formats

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1) 1 dimensional: rod

2) 2 dimensional: sheet

3) 3 dimensional: bulk

4) combinations:

a) rods in 2 dimensions ie netting

b) bulk covered in sheets ie increase in opacity

c) scale adjustments ie filters (as intimated above)

Extras

------

1) The material could be used as a scaffolding which various objects could be

attached to via clips etc. The position and shape of the material could be set up

to place the objects at appropriate positions relative to one another for useful

interaction.

Applications

------------

The number of possible applications for this material would likely be quite large,

hence the following is just a brief sampling of some applications which seemed

particularly appropriate.

1) Small eg

nanoscale and higher structural components ie boxes, struts etc.

nanoscale and higher transport conduits upon which belt mechanisms could be fixed

2) Average eg

macroscopic objects structural components

ropes

netting

cloth with various stiffness depending on sub-millimetre structure (eg 2 sets of

ridges at 90 degrees to each other could allow relatively large flexibility,

stretch)

filters

lenses (if material has a high enough transparency value in certain selected

configurations)

objects where mass is an issue eg cars which if light enough could easily be

powered by efficient solar panels and electric motors

3) Large eg

Skyscrapers, orbital elevators etc

Conclusion

----------

The Fractal Bucky Tube (FBT) as described above, if feasible and economical to

produce in large quantities, could prove extremely beneficial in applications which

do not require the maximum stiffness that a solid diamondoid structure has, and

where an efficient use of mass is a significant advantage.

Detailed analysis would be useful to determine the optimal design for various

required values of stiffness and strength to mass ratio.

Contact

-------

Author : Michael Richards

Email : michaelr@je.com.au

Occupation : Analyst/Programmer

Resident : Canberra, Australia

That's all there is, there isn't any more.