Category Archives: structures

Artificial muscles using folded graphene

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Folded Graphene Concept

Two years ago I wrote a blog on future hosiery where I very briefly mentioned the idea of using folded graphene as synthetic muscles:

https://timeguide.wordpress.com/2015/11/16/the-future-of-nylon-ladder-free-hosiery/

Although I’ve since mentioned it to dozens of journalists, none have picked up on it, so now that soft robotics and artificial muscles are in the news, I guess it’s about time I wrote it up myself, before someone else claims the idea. I don’t want to see an MIT article about how they have just invented it.

The above pic gives the general idea. Graphene comes in insulating or conductive forms, so it will be possible to make sheets covered with tiny conducting graphene electromagnet coils that can be switched individually to either polarity and generate strong magnetic forces that pull or push as required. That makes it ideal for a synthetic muscle, given the potential scale. With 1.5nm-thick layers that could be anything from sub-micron up to metres wide, this will allow thin fibres and yarns to make muscles or shape change fabrics all the way up to springs or cherry-picker style platforms, using many such structures. Current can be switched on and off or reversed very rapidly, to make continuous forces or vibrations, with frequency response depending on application – engineering can use whatever scales are needed. Natural muscles are limited to 250Hz, but graphene synthetic muscles should be able to go to MHz.

Uses vary from high-rise rescue, through construction and maintenance, to space launch. Since the forces are entirely electromagnetic, they could be switched very rapidly to respond to any buckling, offering high stabilisation.

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The extreme difference in dimensions between folded and opened state mean that an extremely thin force mat made up of many of these cherry-picker structures could be made to fill almost any space and apply force to it. One application that springs to mind is rescues, such as after earthquakes have caused buildings to collapse. A sheet could quickly apply pressure to prize apart pieces of rubble regardless of size and orientation. It could alternatively be used for systems for rescuing people from tall buildings, fracking or many other applications.

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It would be possible to make large membranes for a wide variety of purposes that can change shape and thickness at any point, very rapidly.

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One such use is a ‘jellyfish’, complete with stinging cells that could travel around in even very thin atmospheres all by itself. Upper surfaces could harvest solar power to power compression waves that create thrust. This offers use for space exploration on other planets, but also has uses on Earth of course, from surveillance and power generation, through missile defense systems or self-positioning parachutes that may be used for my other invention, the Pythagoras Sling. That allows a totally rocket-free space launch capability with rapid re-use.

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Much thinner membranes are also possible, as shown here, especially suited for rapid deployment missile defense systems:

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Also particularly suited to space exploration o other planets or moons, is the worm, often cited for such purposes. This could easily be constructed using folded graphene, and again for rescue or military use, could come with assorted tools or lethal weapons built in.

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A larger scale cherry-picker style build could make ejector seats, elevation platforms or winches, either pushing or pulling a payload – each has its merits for particular types of application.  Expansion or contraction could be extremely rapid.

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An extreme form for space launch is the zip-winch, below. With many layers just 1.5nm thick, expanding to 20cm for each such layer, a 1000km winch cable could accelerate a payload rapidly as it compresses to just 7.5mm thick!

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Very many more configurations and uses are feasible of course, this blog just gives a few ideas. I’ll finish with a highlight I didn’t have time to draw up yet: small particles could be made housing a short length of folded graphene. Since individual magnets can be addressed and controlled, that enables magnetic powders with particles that can change both their shape and the magnetism of individual coils. Precision magnetic fields is one application, shape changing magnets another. The most exciting though is that this allows a whole new engineering field, mixing hydraulics with precision magnetics and shape changing. The powder can even create its own chambers, pistons, pumps and so on. Electromagnetic thrusters for ships are already out there, and those same thrust mechanisms could be used to manipulate powder particles too, but this allows for completely dry hydraulics, with particles that can individually behave actively or  passively.

Fun!

 

 

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Tackling tornados and hurricanes: The extractor

A tornado has several orders of magnitude less energy than a hurricane, but both can kill people and create enormous damage to lives and property. It would be good to be able to reduce their force by sapping away their energy. The extractor does that. The energy extracted would be in electrical form and could be beamed by microwave to a rectenna array. These would be spread around the areas that suffer most and their costs offset by the high value of the energy collected.

An extractor would be large scale engineering in the sense that it would be very large, but it need not be especially heavy. It would actually be a fairly free-moving but tethered aerial wind farm. Size would be a few kilometres across up to 50km. Depth would be 200-300m.

It could be made entirely of carbon – carbon foam for buoyancy of the structure, graphene or carbon fibre supports and beams to hold the structure together and give the rigidity needed to sap energy from the storm, graphene capacitors for the vertical axis micro-turbine blades, and super-capacitors to store energy pending transmission, graphene string as the spindles for the blades and as wires to conduct the electricity around.

The pieces holding the structure would have a very strong graphene core, lined with buoyant carbon foam, and therefore need little weight still to be supported, so could easily be floated up from the ground and assembled mid air, using carbon foam balloons to hold the assembly platforms, and a high altitude carbon foam balloon could drag it into place and hold it in the storm vicinity once ready.

The struts all lock together to form a fairly rigid structure, but one that could bend a great deal before any damage would result. An extractor could be fifty kilometres across to sap energy from a large storm such as a hurricane, but just a few kilometres would do for a more tightly focused event such as a tornado.

100m square sails would be hung between the struts. Each sail would be made of hundreds of thousands of small S-shaped carbon capacitors, held on a graphene string spindle. As the wind blew on them, the concave side of each capacitor would catch the wind and be forced through a narrow gap. That would bend it further. When it cleared the gap, it would spring back to its normal curvature before being bent and straightening again as it passed through the gap on the other side. The difference in drag between the concave and convex sides provided the force to push the blades through the gaps, and the flexing of the carbon capacitors made the separation between the plates vary, thus creating a voltage change and electrical current. That electrical energy extraction meant less energy for the storm. The electricity was passed through graphene strings to a collector cable which carried the huge aggregated current from each sail.

The overall force on each sail would be high, but the super-strength carbon materials they are made from are easily up to the job. The enormously strong winds in a tornado or hurricane would create massive forces that should normally cause a large sail to be carried with the wind, but due to the massive size of the overall extractor structure, the wind movements at each sail are very different and forces in one direction on the wider structure would be balanced against forces in another. Overall the array creates massive drag that slows the winds. The individual tiny rotating vertical axis vanes don’t care which way they were heading. As long as there is some local relative movement of the air, they would be able to extract energy from that area. High stresses would be generated but the strength of the graphene struts would withstand them. The overall effect would be that the whole array would wander around a bit, but its overall position would be determined by the balloon supporting it far above. The powered balloon would follow the path of the storm and extract as much energy from it as possible, transmitting it by intense microwave beams to earthbound rectenna arrays that have been situated in the areas usually affected.

In this way, huge energy could be extracted from a storm. A tornado could quickly be drained of almost all of its energy and rendered harmless. A hurricane would take longer. Its total energy was many orders of magnitude greater than a tornado, and its overall force would be more gradually siphoned away. Each 100m square sail could extract a few megawatts, and there were a thousand of them on the largest extractors. Siphoning off several gigawatts from a large hurricane could downgrade it substantially within a matter of hours, saving many lives and enormous saving of property damage. The free electricity is just an added bonus. Tornadoes are far smaller and easier to deal with than hurricanes and could quickly be made totally harmless.

High altitude balloons using graphene foam

Graphene foam can be made up of tiny spheres of graphene that contain a vacuum. The graphene spheres are large enough that the average density of the graphene and vacuum is less than helium, so I suggested it as a helium substitute. Here is my original article:

http://timeguide.wordpress.com/2013/01/05/could-graphene-foam-be-a-future-helium-substitute/

It wasn’t long after I wrote it that a Chinese group achieved it, and they subsequently discovered it makes an ideal platform for cultivating stem cells, something that hadn’t even crossed my mind. But that’s engineers for you. Someone invents one idea and someone else runs with it and makes something far better. Anyway, graphene foams already exist today that are 6 times lighter than air.

We hear a lot about high altitude balloons being used for communications, e.g. Google’s Loon project. As is the norm for Google, the idea predates their’s considerably, but never mind, at least they are developing it where others left it on the drawing board.

High altitude balloons so far use helium to achieve the low density. In stark contrast, a huge solid balloon could be made out of graphene foam, and it could be lighter than helium yet stronger than steel. Graphene foam is therefore ideal for making solid balloons for a wide range of purposes.

Way above clouds, the top surface of such a balloon would be perfect to produce solar power for use inside, and the lower side is perfect to transmit this to the ground house communications transponders or simply reflect communication signals.

It could be ideal to house a death ray too, but let’s not think about that for now.

A large, solid, strong balloon could act as an excellent base for a wide range of activities, but it could also be mobile, just like an airship. A combination of special carbon motors such as graphene electron pipes directly powered by energy stored in graphene capacitors. These would be charged with solar electricity generated by from the intense sunlight unimpeded by clouds, the movement of a carbon wire through the magnetic field, thermocouples, solar panels, or harnessing power from high altitude winds. They could even use power harvested from hurricanes and tornadoes, saving many lives and a lot of property too:

https://carbondevices.com/2013/08/11/tackling-tornados-and-hurricanes-the-extractor/

Balloons could also used to deal with forest fires, collecting and storing water directly from clouds and dropping it onto the fire. In fact, these highly positive emergency uses may ultimately be the main reason such a large object would be allowed to remain up in the sky unchallenged in spite of its potential misuses (such as acting the role of mother-ship to a fleet of smaller airships or other weapons). With no need for helium, this kind of solid balloon would be much more environmentally friendly than the traditional variety, perfect for sustainability.

 

Ultra-tall structures – from ground into space

I was 8 when Armstrong and Aldrin set foot on the moon. It was exciting. My daughter is 18 and has never witnessed anything of the same order of excitement. The human genome project was comparable in some ways but lacked the Buzz.

There is excitement about going back now. We will, and on to Mars. We can do space so much more safely now than back in the 60s.  Commercial companies are pioneering space tourism and later on will pioneer the mining bits. But the excitement recently is over the space elevator. The idea is that a cable can stretch all the way from the surface out into space, balanced by gravity, and used as a means to cart stuff back and forth instead of having to use rockets, making it easier, less expensive and less dangerous.

It will happen eventually on Earth. We need to make new materials that are strong enough. Carbon nanotube cables and other fancy materials will be needed that we can’t make long and strong enough yet. But the moon has lower gravity so it is much easier there and will likely happen earlier.

There are plenty of web articles about space elevators already so I don’t need to repeat everything here. But a space elevator is supported from above, a regular building is supported from below. How can we build one very tall from the ground?

I recently issued a report on 2045 construction that among other things also discussed spaceports up to 30km tall:

https://timeguide.wordpress.com/2015/10/21/2045-constructing-the-future/

A 30km tall spaceport on Earth could make use of atmospheric buoyancy for the lower end which of course we wouldn’t get on the moon for the spaceport coming home, but we also wouldn’t get wind on the moon to add stresses. On the moon gravity is less so the structure could be much taller. On the moon a graphene structure could form as much as the bottom 150-200km of the climb. It might offer a nice synergy. The diagram above shows some of the possible structure for the columns, biomimetically inspired by plant stems, though this is just one suggestions, and there are very many ways they could be designed.

This could be enhanced by filling columns with graphene foam:

http://timeguide.wordpress.com/2013/01/05/could-graphene-foam-be-a-future-helium-substitute/

Since I wrote that, carbon foams have been made and they are 6 times lighter than air.

So how about a 30km tall building? Using multilayered columns using rolled up or rippled graphene and nanotubes, in various patterned cross sections, it should be possible to make strong threads, ribbons and membranes, interwoven to make columns and arrange them into an extremely tall pyramid.

This could be used to make super-tall structures for science and tourism or spaceports, or a home for celebrities, well out of sight of the Paparazzi.

Think of a structure like the wood and bark of a tree, with the many tubular fine structures. Engineering can take the ideas nature gives us and optimise them using synthetic materials. Graphene and carbon nanotubes will become routine architectural materials in due course. Many mesh designs and composites will be possible, and layering these to make threads, columns, cross members with various micro-structures will enable extremely strong columns to be made. If the outer layer is coated to withstand vacuum, then it will be possible to make the columns strong enough to withstand atmospheric pressure, but with an overall density the same as the surrounding air or less. Pressure is of course less of an issue higher up, so higher parts of the columns can therefore be lighter still.

We should be able to make zero weight structures in the lower atmosphere, and still have atmospheric buoyancy supporting some of the weight as altitude increases. Once buoyancy fails, the structure will have to be supported by the structure below, limiting the final achievable height.  Optimising the structures to give just enough strength at the various heights, with optimised mesh structure and maximal use of buoyancy, will enable the tallest possible structures. Very tall structures indeed could be made.

So, think of making such a structure, with three columns in a triangular cross-section meeting at 43 degrees at the top (I recall once calculating that is the optimal angle for the strongest A frame in terms of load-bearing to weight ratio, though it ignores buoyancy effects, so ‘needs more work’.

30km tall structures would not be ideal for large scale habitation, since much of the strength in the structure would be to support the upper parts of the structure itself and whatever platform loading is needed. But for a celebrity home, small military observation base or a decent sized lab, it might be fine. The idea may be perfect for pressurised platforms at the top for scientific research, environmental monitoring, telescopes, space launches, tourism and so on. The extreme difference in temperature may have energy production uses too.

Getting the first 30km off the ground without needing any rocket fuel would greatly reduce space development costs, not to mention carbon and high altitude water emissions.

A simple addition to this would be to add balloons to the columns at various points to add extra buoyancy, but they cannot give much extra lift once the atmosphere is too thin so probably wouldn’t make much difference.

Nevertheless, the physics limits are pretty good. 30km is a reasonably achievable goal for a 2045 spaceport, but given the known strength of graphene and carbon nanotubes, a 600km tall building on Earth would be the limit, and that is higher than the Hubble telescope!