Difference between revisions of "Friction"

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This page is meant to be a brief overview covering friction in …
 
This page is meant to be a brief overview covering friction in …
 
* gemstone based nanotech (dedicated page: [[Friction in gem-gum technology]])
 
* gemstone based nanotech (dedicated page: [[Friction in gem-gum technology]])
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Practical bearings can have quite thin stacks of bearing layers. <br>
 
Practical bearings can have quite thin stacks of bearing layers. <br>
 
Thin from the human scale perspective.
 
Thin from the human scale perspective.
 +
 +
'''Also related here is [[mesoscale friction]] and [[atomically precise roller gearbearing]]s.''' <br>
 +
Not roller bearings as friction may be too low for that. That is: Superlubricating rollers may slide rather than roll. <br>
 +
Going to [[atomically precise roller gearbearing]]s should lower friction quite a bit further judging from the per area friction loss levels of macroscale bearings. <br>
 +
But it also introduces voids and larger runway surface area per bearing eventually reintroducing gradual wear e.g. by radiation hits. <br>
 +
Atomically tight seals still can prevent any and all gunk from getting in from the outside. So only internal seed-damage can self-amplify. <br>
 +
Atomically tight seals need contact all around and thus remain a big contributor of friction. <br>
 +
Still they can be small in surface area compared to the gearbearings runway. <br>
 +
Runway only contributes to friction at and near the roller contacts. <br>
 +
'''Identifying a sweet spot for atomically precise gear-bearing size remains an open question.''' <br>
  
 
== Related ==
 
== Related ==
  
 
* '''[[Friction in gem-gum technology]]'''
 
* '''[[Friction in gem-gum technology]]'''
 +
* [[Reciprocative friction in gem-gum technology]]
 +
* [[Friction in diffusion transport]]
 
* '''[[Superlubricity]] reducing friction'''
 
* '''[[Superlubricity]] reducing friction'''
 
* [[How friction diminishes at the nanoscale]]
 
* [[How friction diminishes at the nanoscale]]

Latest revision as of 12:27, 1 April 2024

This page is meant to be a brief overview covering friction in …

Nanoscale friction

In gemstone metamaterial technology

Despite higher bearing surface area of smaller machinery
the friction in gem-gum technology stays manageable.

Friction not being a show-stopper is due to:

There are dissipation mechanisms that scale linear with speed but these are specific to reciprocative motions only.

(1) How nanomachineries innate high throughput density reduces friction

Higher throughput of smaller machinery leads to very little amount of nanomachinery needed
and thus to reasonably low bearing surface area within that.

(2) How the dynamic character of nanobearing friction can be exploited to reduce friction

Given quadratic gains in efficiency one wants to do a deliberate slowdown at the lower assembly levels where this type of friction is present.
Keeping throughput constant this means one needs to compensate for the loss of throughput with more nanomachinery.
More nanomachinery means a linear increase in losses. Quadratic gains times linear losses equals linear gains.
Overall linear gains in efficiency are still good and worth pursue.
See: Increasing bearing area to decrease friction

Recycle to reduce friction (not applicable to first time production)

Also a good design averts the need to disassemble things down to nanoscopic parts if
only larger scale reconfigurations are needed. – See: Convergent assembly
This kind of aversion of frictive losses only applies to recycling though.
Making recycling all the more desirable end economically viable. Nice!

Further reading

See main page: Friction in gem-gum technology This contains quantitaive estimations.

A bit more detailed but still brief exlanations to these effects/factors
can be found on the page How friction diminishes at the nanoscale.

In existing nanotechnologies

Stiff

  • Pretty much the only case where the above can already be experimentally tested (as of 2021) is in nested nanotubes and sliding graphene sheets.
  • At the microscale with MEMS there is the issue with stiction. Which may paint a misleading picture of how friction and wear scales when going down even further the sizescales.

Soft

It's hard to talk about friction is systems that are akin to biological cells.
It's obviously not that there are no energy dissipation losses.
There necessarily are other energy devaluating mechanisms that are not "friction".
While in thermally driven diffusion transport there is no "friction" the energy needs to be "expended" at the "pitstops" instead.
This is necessary in order to prevent reactions and diffusion transports to run backwards.
Related: Arrow of time.

Stiff artificial nanosystems could be superior to soft nanosystems (natural and artificial)
because they may allow for more complete energy recuperation
using dissipation sharing. That is the "energetic change money" is not lost.

Side-note: This only regards comparison of energy efficiency
not comparison of maximal performances and operational ranges which both
are clearly vastly superior in stiff nanosystems.

Macroscale friction

Classical friction

There is classical friction with the friction coefficient µ.
Present e.g. in dry sliding sleeve bearings.

  • This type of friction is in first approximation independent of sliding (or rolling) speed
  • This type of friction is in first approximation independent of contact area
  • This type of friction is in dependent on normal force (load)

Dynamic drag

There is dynamic drag in liquids and gasses.
Present e.g. in hydrostatic and hydrodynamic bearings.

  • This type of friction is dependent on speed
  • This type of friction is dependent on contact area
  • there is dependence on normal force (load) but it requires an extended model.

Macroscale bearings made form gemstone based nanomachinery

This is about the gemstone based metamaterial that is infinitesimal bearings.
Distributing the speed difference over many layers can give low friction per bearing area even for higher speeds.
The rising total bearing interface are is overcompensated by the drop in friction from dropping speed.
Overall doubling the thickness of the stack of bearing layers halves the friction.
A inverse proportional linear relationship.

Practical bearings can have quite thin stacks of bearing layers.
Thin from the human scale perspective.

Also related here is mesoscale friction and atomically precise roller gearbearings.
Not roller bearings as friction may be too low for that. That is: Superlubricating rollers may slide rather than roll.
Going to atomically precise roller gearbearings should lower friction quite a bit further judging from the per area friction loss levels of macroscale bearings.
But it also introduces voids and larger runway surface area per bearing eventually reintroducing gradual wear e.g. by radiation hits.
Atomically tight seals still can prevent any and all gunk from getting in from the outside. So only internal seed-damage can self-amplify.
Atomically tight seals need contact all around and thus remain a big contributor of friction.
Still they can be small in surface area compared to the gearbearings runway.
Runway only contributes to friction at and near the roller contacts.
Identifying a sweet spot for atomically precise gear-bearing size remains an open question.

Related

External links

Table of Contents

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