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Title: Ambient-temperature passive magnetic bearings: Theory and design equations

Abstract

Research has been underway at the Lawrence Livermore National Laboratory to build a theoretical and experimental base for the design of ambient-temperature passive magnetic bearings for a variety of possible applications. in the approach taken the limitations imposed by Earnshaw`s theorem with respect to the stability of passive magnetic bearing systems employing axially symmetric permanent-magnet elements are overcome by employing special combinations of elements, as follows: Levitating and restoring forces are provided by combinations of permanent-magnet-excited elements chosen to provide positive stiffnesses (negative force derivatives) for selected displacements (i.e., those involving translations or angular displacement of the axis of rotation). As dictated by Eamshaw`s theorem, any bearing system thus constructed will be statically unstable for at least one of the remaining possible displacements. Stabilization against this displacement is accomplished by using periodic arrays (`Halbach arrays`) of permanent magnets to induce currents in close-packed inductively loaded circuits, thereby producing negative force derivatives stabilizing the system while in rotation. Disengaging mechanical elements stabilize the system when at rest and when below a low critical speed. The paper discusses theory and equations needed for the design of such systems.

Authors:
;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Financial Management and Controller, Washington, DC (United States)
OSTI Identifier:
302210
Report Number(s):
UCRL-JC-129214; CONF-980832-
ON: DE98057423; BR: YN0100000
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 6. international symposium on magnetic bearings, Cambridge, MA (United States), 5-7 Aug 1998; Other Information: PBD: 30 Dec 1997
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; MAGNETIC BEARINGS; AMBIENT TEMPERATURE; PERMANENT MAGNETS; DESIGN

Citation Formats

Post, R F, and Ryutov, D D. Ambient-temperature passive magnetic bearings: Theory and design equations. United States: N. p., 1997. Web.
Post, R F, & Ryutov, D D. Ambient-temperature passive magnetic bearings: Theory and design equations. United States.
Post, R F, and Ryutov, D D. 1997. "Ambient-temperature passive magnetic bearings: Theory and design equations". United States. https://www.osti.gov/servlets/purl/302210.
@article{osti_302210,
title = {Ambient-temperature passive magnetic bearings: Theory and design equations},
author = {Post, R F and Ryutov, D D},
abstractNote = {Research has been underway at the Lawrence Livermore National Laboratory to build a theoretical and experimental base for the design of ambient-temperature passive magnetic bearings for a variety of possible applications. in the approach taken the limitations imposed by Earnshaw`s theorem with respect to the stability of passive magnetic bearing systems employing axially symmetric permanent-magnet elements are overcome by employing special combinations of elements, as follows: Levitating and restoring forces are provided by combinations of permanent-magnet-excited elements chosen to provide positive stiffnesses (negative force derivatives) for selected displacements (i.e., those involving translations or angular displacement of the axis of rotation). As dictated by Eamshaw`s theorem, any bearing system thus constructed will be statically unstable for at least one of the remaining possible displacements. Stabilization against this displacement is accomplished by using periodic arrays (`Halbach arrays`) of permanent magnets to induce currents in close-packed inductively loaded circuits, thereby producing negative force derivatives stabilizing the system while in rotation. Disengaging mechanical elements stabilize the system when at rest and when below a low critical speed. The paper discusses theory and equations needed for the design of such systems.},
doi = {},
url = {https://www.osti.gov/biblio/302210}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 30 00:00:00 EST 1997},
month = {Tue Dec 30 00:00:00 EST 1997}
}

Conference:
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