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ACOUSTIC JOURNAL BEARING – A SEARCH FOR ADEQUATE CONFIGURATION
Tadeusz StolarskiRafal GawarkiewiczKrzysztof Tesch
ITC 2015, Tokyo, Japan
Gdansk University of TechnologyFaculty of Mechanical Engineering, Poland
AIM OF PROJECT
Aim of project was to find appropriate geometry to maximise acoustic pressure generation. This was done by using FEM method
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In order to select the most appropriate configuration (geometry) experimental testing was carried out using specially designed rig
There were many different geometries analysed. Finally three configurations were considered for experimental testing
1-st CONFIGURATION CHOSEN FOR EXPERIMENTAL RESEARCH – SOLID MODEL IMAGE
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bearing surface vibrating and elastically deforming
location for PZT
arm for full constraining of the
bearing
1-st CONFIGURATION – RESULTS OF NUMERICAL ANALISYSOF DEFORMATION PRODUCED BY PZTs
4
NODAL SOLUTION
SUB =1
UXRSYS=1DMX =.753E-03
MN
MX
-.139E-03-.394E-04.596E-04.159E-03.258E-03.357E-03.456E-03.555E-03.654E-03.753E-03
(Lozysko_S_104_PIEZO) Voff=60V + Vamp=35V (x3319.37072)
Radial deformation [mm] (3300x magnification of deform.)
NODAL SOLUTION
SUB =1
UXRSYS=1DMX =.746E-03
MN
MX
-.136E-03-.383E-04.598E-04.158E-03.256E-03.354E-03.452E-03.550E-03.648E-03.746E-03
(Lozysko_S_104_PIEZO) Voff=60V + Vamp=35V (x3319.37072)
Radial deformation [mm] of inner surface of bearing
(3300x magnification of deform.)
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NODAL SOLUTION
SUB =13FREQ=21783.5USUMRSYS=1DMX =333.286
MN
MX
037.031774.0635111.095148.127185.159222.19259.222296.254333.286
Lozysko_S_104_MODAL Mode 13: 21784 Hz {x5.094308962E-03}
Acceptable modal shape – total deformation [-]
1-st CONFIGURATION – EXAMPLE RESULT OF NUMERICAL ANALISYSFOR PROPER MODAL SHAPE
NODAL SOLUTION
SUB =13FREQ=21783.5UXRSYS=1DMX =333.286
MNMX
-332.108-258.309-184.51-110.712-36.913236.8855110.684184.483258.281332.08
Lozysko_S_104_MODAL Mode 13: 21784 Hz {x5.094308962E-03}
Acceptable modal shape – radial deformation [-]
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2-nd CONFIGURATION CHOSEN FOR EXPERIMENTAL RESEARCH – SOLID MODEL IMAGE
6
bearing surface vibrating and elastically deforming
location for PZT
arm for full constraining of the
bearing
2-nd CONFIGURATION – RESULTS OF NUMERICAL ANALISYSOF DEFORMATION PRODUCED BY PZTs
NODAL SOLUTION
SUB =1
UXRSYS=1DMX =.002931
MN
MX
-.925E-03-.496E-03-.677E-04.361E-03.789E-03.001218.001646.002074.002503.002931
(Lozysko_trl11_PIEZO) Voff=60V + Vamp=35V (1200x)
Radial deformation [mm] (1200x magnification of deform.)
NODAL SOLUTION
SUB =1
UXRSYS=1DMX =.002931
MN
MX
-.924E-03-.496E-03-.673E-04.361E-03.789E-03.001218.001646.002074.002503.002931
(Lozysko_trl11_PIEZO) Voff=60V + Vamp=35V (1200x)
Radial deformation [mm] of inner surface of bearing
(1200x magnification of deform.)
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2-nd CONFIGURATION – EXAMPLE RESULT OF NUMERICAL ANALISYSFOR PROPER MODAL SHAPE
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Total deformation practically defined by radial deformation
Acceptable modal shape – total deformation [-]
NODAL SOLUTION
SUB =12FREQ=11350.5USUMRSYS=0DMX =684.23
MN
MX
076.0255152.051228.077304.102380.128456.153532.179608.204684.23
o ysko trl11_wykonana MODAL ANS--Modal (A5)
3-rd CONFIGURATION CHOSEN FOR EXPERIMENTAL RESEARCH – SOLID MODEL IMAGE
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slot for PZTfully constrained outer surface
vibrating bearing surface elastically deforming into three-lobe configuration
multiple elastic hinges
3-rd CONFIGURATION – RESULTS OF NUMERICAL ANALISYSOF DEFORMATION PRODUCED BY PZTs
NODAL SOLUTION
SUB =1
UXRSYS=1DMX =.003002
MN
MX
-.00284-.002259-.001679-.001099-.519E-03.616E-04.642E-03.001222.001802.002383
(f_wgOLD_mdf2b_piezo_2PZT) Voff=60V + Vamp=35V (500x)
Radial deformation [mm] (500x magnification of deform.)
NODAL SOLUTION
SUB =1
UXRSYS=1DMX =.002698
MN
MX
-.002698-.002136-.001575-.001013-.452E-03.110E-03.672E-03.001233.001795.002356
(f_wgOLD_mdf2b_piezo_2PZT) Voff=60V + Vamp=35V (500x)
Radial deformation [mm] of inner surface of bearing
(500x magnification of deform.)
10
3-rd CONFIGURATION – EXAMPLE RESULT OF NUMERICAL ANALISYSFOR PROPER MODAL SHAPE
Acceptable modal shape – total deformation [-]
NODAL SOLUTION
SUB =7FREQ=7326.15UXRSYS=1DMX =290.388
MN
MX
-167.104-117.737-68.3692-19.001830.365679.733129.1178.468227.835277.203
Acceptable second modal shape – total deformation [-]
NODAL SOLUTION
SUB =19FREQ=27242.4UXRSYS=1DMX =501.769
MN
MX
-111.859-61.016-10.173540.669191.5117142.354193.197244.039294.882345.724
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SOLID MODEL IMAGE OF THE TEST RIG
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air turbine drive
shaft's speed sensor
end part of housing fixed to the tilting table
special torque meter attached here
shaft
test aparatus housing
aerostatic thrust bearing
thrust bearing air supply
test bearing
shaft's position sensor
MODEL OF DEVICE FOR TORQUE MEASUREMENTS
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supporting plate fixed to the housing of the apparatus
strain gaugebeamtube attached to the rotating shaft
shaft loaded by friction torque developed in tested bearing
DEVICE FOR TORQUE MEASUREMENTS
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TEST RIG (with device for torque measurements)
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TEST RIG (without device for torque measurements)
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THE TEST RIG (with bearing of 3-rd configuration)
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PICTURES OF TESTED BEARINGS
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1
2
3
RESULTS OF EXPERIMENTAL RESEARCH – 1-st CONFIGURTION DRIVING TORQUE
19Driving torque as a function of the load applied to the bearing operating at 58.7 kHz
By tilting the base of the rig, load was applied on the test bearing. For a given tilt angle torque required to initiate rotation of the shaft was measured. This procedure was repeated
for a number of the tilt angles (loads)
RESULTS OF EXPERIMENTAL RESEARCH – 2-nd CONFIGURTION DRIVING TORQUE
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Driving torque as a function of the load applied to the bearing operating at 36.7 kHz
RESULTS OF EXPERIMENTAL RESEARCH – 3-rd CONFIGURTION DRIVING TORQUE
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Driving torque as a function of the load applied to the bearing operating at 8.4 kHz
RESULTS OF EXPERIMENTAL RESEARCH – 3-rd CONFIGURTION DRIVING TORQUE (cont.)
22Driving torque as a function of the load applied to the bearing operating at 27.2 kHz
Two resonance frequencies because the 3-rd configuration was much more flexible than the other two
1. Results testify to the feasibility of the idea of a journal air bearing operating on a squeeze film acoustic levitation principle
2. Geometric configuration of an acoustic bearing proved to be a very important factor governing the load supporting capacity
3. Bearing possessing low overall stiffness which is provided by geometric configuration attested to much higher load capacity comparing to the other two configurations tested
4. Increased flexibility of the bearing directly translates into bigger elastic deformation amplitude of the initially circular bore and hence improved ability to separate interacting surfaces. This is only valid with the assumption that the force generated by PZT and responsible for elastic deformation of the bearing is kept constant
5. The most appropriate geometry was found to be 3-rd configuration
CONCLUSIONS OF THE TESTING
Gdansk University of TechnologyFaculty of Mechanical Engineering, Poland
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THE MOST APPROPRIATE GEOMETRY (3-rd CONFIGURATION)
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ACKNOWLEDGEMENTS
Gdansk University of TechnologyFaculty of Mechanical Engineering, Poland
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The authors would like to acknowledge the financial support for the research reported in this paper by the grant
from the National Centre of Science, Poland (Grant no.: 2012/07/B/ST8/ 03683)
Thank you for your attention
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Gdansk University of TechnologyFaculty of Mechanical Engineering, Poland