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

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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

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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.)

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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

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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