Difference between revisions of "Friction"

Revision as of 10:27, 17 September 2021

Nanoscale friction

In gemstone metamaterial technology

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

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

This is due to:

• (1) Convergent assembly or equivalently ...
• (2) Higher throughput of smaller machinery and ...
• (X) Superlubricity

A bit more detailed but still brief eplanations 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.

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

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.

Related

• Friction in gem-gum technology
• Superlubricity reducing friction
• How friction diminishes at the nanoscale
• Friction mechanisms
• Rising surface area causing more friction
• Macroscale style machinery at the nanoscale – Common misconceptions about atomically precise manufacturing
• Feynman path – A naive form of scaling down saw blades and drills to the nanoscale (infeasible)
• Pages with math
• Evaluating the Friction of Rotary Joints in Molecular Machines (paper)

External links

• Evidence of misconception: See section: "Fundamental Concepts" Wikipedia: Nanoelectronics (2017-04-12) (common false negatives).
• Nanomachines: How the Videos Lie to Scientists (Eric Drexlers metamodern blog (archive) 2009-02-10)

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