Chemospring
Contents
The begin of a basic concrete design
Take the idea of seamless covalent welding, but make the interfaces sparse.
This way pulling the welded together crystolecules reliably breaks the bonds at the desired interface.
One gets a reversible (albeit weaker) interface instead of the typical irreversible interface when seamless covalent welding is done densely.
Pulling the interface only slightly apart one gets a very stiff short range spring action.
Take cylindrical crystolecule disks and put such sparse seamless covalent welding interfaces on both sides.
Putting multiple such disks in series (and possibly adding gear-down mechanisms too) can give intentionally weaker and longer range less stiff spring action
with same force times distance energy take-up capacity (aka spring toughness).
When the sparse covalent interfaces in series are stretched to very high bond strains then care must be taken.
Nonlinear force over distance leads to some weird behaviors if no engineering measures are taken against them.
See below in the section about nonlinear effects.
(wiki-TODO: Add 1D simplified block diagram illustration)
The basic abstract idea
A "spring" in a box that does not stretch bonds slightly but use them to their full extent, that is break them fully.
Normally bonds in mechanical springs get stretched/strained only a very tiny fraction
of the distance at which they exert the maximal restoring force.
The idea here is to to make functional metamaterial cells
with internal geometry such that for a lot of internal bonds their whole range of stretching can be used for spring action.
Chemospring metamaterial cells could possibly be packaged into microcomponents but smaller or bigger structure would works too.
This extreme bending of many bonds blurs the line between
- bond breakage and formation in chemomechanical converters and
- conventional mechanical springs.
Just as in chemomechanical converters there is quite some overhead in structural framework material necessary to keep the actively hyper-stretched bonds in place.
High non-linearity and effects
When bonds are strained beyond their maximum of the restoring force a number of interesting things happen.
When a constant pulling force is applied then the bonds will stretch infinitely (aka fully rupture).
This will only stop if the design is such that other bonds kick in helping to prevent any further rip-apart.
Such a design is desirable.
When chemical bonds are naively put in series,
e.g. in the form of a stack of sparse seamless covalent welding interfaces,
then it comes to an instability. All the stretching will concentrate in just one interface of the interfaces that are put in series.
Which one that is is completely random. Determined by thermal motion and or quantum randomness.
- This is kinda similar to when one puts LEDs into parallel with only one common series resistor which is a bad idea.
It should be possible to devise mechanisms that make sure the stretching strain is equally divided over all the bonds in series.
The necessary control forces should be much smaller than the controlled forces.
- This is kinda similar to the enforcing a linear speed gradient in infinitesimal bearings.)
Power density vs energy density
Chemosprings lie in the middle between:
- simple crystolecule springs (enormously high power densities very low energy densities)
- chemical converters (lower power densities maximal chemical energy densities)
Maximizing metamaterial toughness
Macroscale crash shock absorption: what normally goes into plastic deformation heat (picture crushed metal in a car crash test) goes into cool (reversible) bond breaking.
So chemosprings may be especially good at shock absorption where it's important
to take up a lot of energy in a quite short amount of time.
E.g. convert the energy from a macroscopic high speed collision
into fully reversible internal deformation energy with as little thermal heat-up as possible.
Thermal heat up can be used as additional energy dissipation mechanism
but by putting as much of it as possible in chemical energy the metamaterial
can cope with a lot harder blows.
This can be seen in that converting chemical energy into thermal energy can lead to enormous temperatures
way higher than 1000K which would be very destructive for many kinds of nanomachinery.
Beside less impact energy being possible to take up purely by thermal heat-up dissipation into heat is also more wasteful.
A localized heatup is much harder to recuperate into useful mechanical energy. And limited by the maximal Carnough efficiency.
If one even attempts to implement means for thermal energy recuperation to begin with that is.
Possible advanced extended functionalities
- Isotropic or custom tailored elasticity emulation internally using chemospring designs.
- Chemosprings with controllable lock and release functionalities
- Combinations with muscle motors electromechanically or chemomechanically driven.
Why not using elastomers as springs
- Hanleable energy and power density is probably lower.
- Singly linked polymers are much more susceptible to radiation damage
- Singly linked polymers are more susceptible to thermal damage.
Inclusion of fragile polymer chains may drag the whole systems maximal operation temperature down. See: Consistent design for external limiting factors
