Negative pressure bearing - Revision history

Apm: Category:Surprising facts

2026-03-29T20:34:10Z

← Older revision		Revision as of 22:34, 29 March 2026
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	[[Category:Far term target]]		[[Category:Far term target]]
			[[Category:Surprising facts]]

Apm: Category:Far term target

2026-03-29T18:15:05Z

Category:Far term target

← Older revision		Revision as of 20:15, 29 March 2026
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	Macroscale engineering terms like "press fit" may not be too well usable for strained shell bearings.		Macroscale engineering terms like "press fit" may not be too well usable for strained shell bearings.
	Even slightly undersized undersized press fits might still suck axles in due to VdW force maximizung surface contact area.		Even slightly undersized undersized press fits might still suck axles in due to VdW force maximizung surface contact area.

			[[Category:Far term target]]

Apm: Apm moved page Negative pressure bearings to Negative pressure bearing over redirect: plural => singular

2025-12-05T06:53:51Z

Apm moved page Negative pressure bearings to Negative pressure bearing over redirect: plural => singular

← Older revision	Revision as of 08:53, 5 December 2025
(No difference)

Apm: /* Related / Levitation

2023-11-05T15:39:59Z

Related: * Levitation

← Older revision		Revision as of 17:39, 5 November 2023
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	* [[Nonbonded interactions]]		* [[Nonbonded interactions]]
	* [[Gemstone-like molecular element#Strained shell structures]]		* [[Gemstone-like molecular element#Strained shell structures]]
			* [[Levitation]]

	'''Going the opposite way:'''		'''Going the opposite way:'''

Apm: added relevant image

2023-11-05T15:39:22Z

added relevant image

← Older revision		Revision as of 17:39, 5 November 2023
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			[[File:0415tenseBear.gif\|400px\|thumb\|right\|Bearings can be stable despite attractive interactions between their surfaces – Graphic by Eric K. Drexler]]

	In [[superlubricity\|suberlubricating]] strained shell sleeve bearings when the gap between the axle and the sleeve is gradually increased in size by deliberate design changes,		In [[superlubricity\|suberlubricating]] strained shell sleeve bearings when the gap between the axle and the sleeve is gradually increased in size by deliberate design changes,

Apm: Added most relevant link to Eric Drexlers former page on the topic.

2023-08-15T07:37:51Z

Added most relevant link to Eric Drexlers former page on the topic.

← Older revision		Revision as of 09:37, 15 August 2023
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	The effect has its onset at the minimum of the [[Lennard Jones potential]] and at the zero of its first derivative (the force) where it flips from repulsive to attractive.		The effect has its onset at the minimum of the [[Lennard Jones potential]] and at the zero of its first derivative (the force) where it flips from repulsive to attractive.
	The effect becomes unstable once the gap crosses the inflection point of the [[Lennard Jones potential]] which is the maximum of attractive (or minimum of repulsive) force and the zero of the second dreivative (of stiffness), where one goes from positive stiffness to negative stiffness. Negative stiffness means when you pull the counter-force gets weaker, you have a runaway process, the situation becomes unstable. For related infos check out the page: [[Energy, force, and stiffness]].		The effect becomes unstable once the gap crosses the inflection point of the [[Lennard Jones potential]] which is the maximum of attractive (or minimum of repulsive) force and the zero of the second dreivative (of stiffness), where one goes from positive stiffness to negative stiffness. Negative stiffness means when you pull the counter-force gets weaker, you have a runaway process, the situation becomes unstable. For related infos check out the page: [[Energy, force, and stiffness]].

			== External links ==

			Archived from Eric Drexlers former website:
			* '''[https://web.archive.org/web/20160314130257/http://e-drexler.com/p/04/03/0322nonrepulsive.html Bearings can be stable despite attractive interactions between their surfaces]'''

	== Related ==		== Related ==

Apm: /* Related */

2021-05-26T19:19:04Z

← Older revision		Revision as of 21:19, 26 May 2021
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	== Related ==		== Related ==

	* Minimal friction [[superlubricity]] may lie in the negative pressure regieme. {{todo\|invetsigate this}}		* [[Superlubrication]]: Minimal friction [[superlubricity]] may lie in the negative pressure regieme. {{todo\|invetsigate this}}
	* Stretching interpretation a bit negative pressure bearings maybe could be counted to the methods for [[levitation]] at the nanoscale.		* Stretching interpretation a bit negative pressure bearings maybe could be counted to the methods for [[levitation]] at the nanoscale.
	* [[Nonbonded interactions]]		* [[Nonbonded interactions]]
	* [[Gemstone-like molecular element#Strained shell structures]]		* [[Gemstone-like molecular element#Strained shell structures]]
	* [[Superlubrication]]

	'''Going the opposite way:'''		'''Going the opposite way:'''

Apm: /* Related */ added link to page: Superlubrication

2021-05-26T19:18:19Z

Related: added link to page: Superlubrication

← Older revision		Revision as of 21:18, 26 May 2021
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	* [[Nonbonded interactions]]		* [[Nonbonded interactions]]
	* [[Gemstone-like molecular element#Strained shell structures]]		* [[Gemstone-like molecular element#Strained shell structures]]
			* [[Superlubrication]]

	'''Going the opposite way:'''		'''Going the opposite way:'''

Apm: added sections == Range of presence and stability ==

2020-09-10T16:47:38Z

added sections == Range of presence and stability ==

← Older revision		Revision as of 18:47, 10 September 2020
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	{{wikitodo\|add a sketch to illustrate the situation}} <br>		{{wikitodo\|add a sketch to illustrate the situation}} <br>
	{{wikitodo\|illustrate the range between where negative pressure starts and where the situation becones unstable via lennard jones potential and its first and second derivatives}}		{{wikitodo\|illustrate the range between where negative pressure starts and where the situation becones unstable via lennard jones potential and its first and second derivatives}}

			== Range of presence and stability ==

			The effect has its onset at the minimum of the [[Lennard Jones potential]] and at the zero of its first derivative (the force) where it flips from repulsive to attractive.
			The effect becomes unstable once the gap crosses the inflection point of the [[Lennard Jones potential]] which is the maximum of attractive (or minimum of repulsive) force and the zero of the second dreivative (of stiffness), where one goes from positive stiffness to negative stiffness. Negative stiffness means when you pull the counter-force gets weaker, you have a runaway process, the situation becomes unstable. For related infos check out the page: [[Energy, force, and stiffness]].

	== Related ==		== Related ==

Apm: basic version of the page

2020-09-10T16:30:48Z

basic version of the page

New page

In [[superlubricity|suberlubricating]] strained shell sleeve bearings when the gap between the axle and the sleeve is gradually increased in size by deliberate design changes,
then it can get to the point where the axle and the sleeve go from mutually repelling each other (akin to a macroscale press fit) to mutually attracting each other.
And that well before the situation becomes unstable and the axle snaps to one side of the sleeve.

Effectively there is a negative pressure between axle and sleeve:
* pulling the surface of the axle outward in all directions to the sleeve and
* pulling the surface of the sleeve inward to the axle

Maximizing of gap size leads to maximization of negative pressure and mimimization of potential waviness. <br>
This leads to the following open questions:
* Does the maximally stable gap size correspond to minimal power dissipation? This would be a natural design goal for ultra low dissipation bearings for low loads but high speeds.
* Or is the gap size of minimal dissipation closer to the zero pressure point? Is there a notable speed dependence?
* How big is the gap typically just before the situation gets unstable?
{{Todo|Answer above questions.}}

{{wikitodo|add a sketch to illustrate the situation}} <br>
{{wikitodo|illustrate the range between where negative pressure starts and where the situation becones unstable via lennard jones potential and its first and second derivatives}}

== Related ==

* Minimal friction [[superlubricity]] may lie in the negative pressure regieme. {{todo|invetsigate this}}
* Stretching interpretation a bit negative pressure bearings maybe could be counted to the methods for [[levitation]] at the nanoscale.
* [[Nonbonded interactions]]
* [[Gemstone-like molecular element#Strained shell structures]]

'''Going the opposite way:'''
* [[High pressure]] -- [[Dissipative friction elements]]
* [[Design of Crystolecules#avoid too high interface pressure in sleeve bearings]]
Macroscale engineering terms like "press fit" may not be too well usable for strained shell bearings.
Even slightly undersized undersized press fits might still suck axles in due to VdW force maximizung surface contact area.