Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Sophisticated simulation tools for

investigation of roller bearings

to improve the reliability of wind

turbine gears

Prof. Dr.-Ing. Bernd Sauer,

University of Kaiserslautern, Germany

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Quelle: Bosch Rexroth

Quelle: Winergy

HUSUM WindEnergy 2008

Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

MEGTat a Glance

Institute of Machine Elements, Gears, and Transmissions

University of Kaiserslautern

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Chair of Machine Elements, Gears and Transmissions Professor Dr.-Ing. Bernd Sauer

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

personal data: Prof. Dr.-Ing. Bernd Sauer

• Studies of mechanical engineering at the TU Berlin

• 1988 PHD at the Technische Universität Berlin.

• More than 10 years industrial experience, head of development

department, gears and drives of railway vehicles, responsible for

intercity train development

• Since 1998 chair of machine elements, gears and drives atUniversity of Kaiserslautern

• Chairman of the advisory board “Vibration and active systems” of VDI (Association of German Engineers) and the standard group NALS (NormenausschussAkustik, Lärminderung und Schwingungstechnik) within DIN organisation

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Virtual Product development of wind turbines

in the last decade:

● engineering tools for wind applications

● research tools for components and elements

topic today

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

In many wind turbine drive trains gears are in

operation

the main components in the gear system are:

● gear wheels

● bearings, in many cases roller bearings

topic today

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Research tools for roller bearings are available at

the leading bearing companies, e.g. Schaeffler, SKF

Some scientific institutes has developed comparable

simulation tools

Introduction and presentation of the University

Kaiserslautern development “BEARS-Kl08”:

Bearing Simulationtool

Research of roller bearing and bearing application

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

1. steady static loaded bearing = stressed dynamically

2. varying external load = dynamically stressed again

3. only a few rules to estimate the dynamic operation

condition

BEARS

What’s the goal and the advantage of roller bearing dynamic simulation with BEARS ?

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Target

Challenges: Simulation of the dynamical behaviour of machine elements with rolling-sliding contacts

Ambition: Estimate the in-service behaviour under different operation conditions

Virtual Product development

Quelle: FAG

Quelle: Bosch Rexroth

Quelle: MSC Software

Component

Subsystem

System

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Method of resolution

Strategy: Use of commercial software

Challenges: Implementation of „machine element -physics“

accuracy and performance

Requirement: parametric and modular model strukture

contact geometry

contact forces

lubrication conditions

macro-elasticity

work packages

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

The Approach

Dynamic Simulation ofRolling Bearings and Linear Motion Guides

Commercial MBS Code

ADAMS by MSC.Software Co.

ADAMS/View ADAMS/Flex …

Normal ContactContact Detection Friction

Mixed ~

EHL

Lubricant

Load

Pressure

Damping

Stability

Accuracy

Perform.

I II III

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Example ball bearing without cage – forces amongst balls

RKL6212, Clearance: 0µmLoad : 0...1000N radialSpeed: 0...1000 1/min

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Dynamic Results – CRB: Thrust Force under Misalignment

Pr

Lastzone

+lk

b)

+γ

a)

Rechtslauf

+Pa /2

+Pa /2

Z

Pr

Lastzone

+lk

b)

+γ

a)

Rechtslauf

+Pa /2

+Pa /2

Z1) Excentric Load Pr (NU1020ML, simple friction law m = 0,05)

+nvgl [mm/s]

µ

0,05

1,0

-600

-300

0

300

600

-20 -15 -10 -5 0 5 10 15 20

lk [mm]

Pa [N]

Messung, Pr=14.715NMessung, Pr=9.810NMessung, Pr=4.905NMKS, Pr=14.715NMKS, Pr=9.810NMKS, Pr=4.905N

+ thrust force dependent on radial load magnitude

+ thrust force dependent on sign of eccentricity

+ thrust force not dependent on direction of revolution

- measurements show larger dependencyof the magnitude of eccentricity±n

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Problem & Challenge: Cage Dynamics

bearing cages are under complex load conditions during application time

these conditions can lead to limitations of functionality or – in extreme cases –to limitation of lifetime

Source: Die Wälzlagerpraxis Source: FAG

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Cage Pocket Dynamics

DGBB 6212MA, FVA Ref. Oil no. 3 at 50°C, Frad=1000N, nIR=1000 rev/min

I II III IV I

Mag. of Normal load in pocket contact

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Frad

Fax

r=0,2 mm

results – dynamic-simulation (2)

Orbital movement of the cage centre point

horizontalcage position

vertical cage position comparison:

FEM-cage macro-elastic cage

ball bearing 6205MB,

inner race guided cage,

temperature 300°C,

Frad=1000N, Fax=1000N,

nIR=1500U/min

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

I II III IV V

Investigation of bearing 6212 restricted

test rig KFDYN cages dynamics

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

results – orbit of the cages centre

ball bearing, outer race guided, brass cage,temperature 45°C, Frad=1000N, Fax=1000N, nIR=1000U/min

Fr

adFa

x

Comparison:

Measurement

Macro-elastic Cage

Ver

tica

l ca

ge

posi

tion

Horizontal cage position

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

test rig friction of complex loaded rolling bearings

• bending stiffness: 50.000 Nµm• speed range : n = 0 - 15000 rpm • tipping : g = +/- 3°• tipping out of load plane: b = +/- 3°

hydrostatic support bearing

linear guide

turn guide

friction moment module

tipping - moduletest bearing

test rig data:• max. bearing diameter: 200 mm• radial load: Fr, max = 70 kN• axial load: Fa, max = 30 kN

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Simulation results (1)

- Zylinderrollenlager: NUP212E- Axiale Belastung Pa=443 N

- Radiale Belastung Pr=1430 N- Drehzahl n=0...3000 min-1

- Schmierstofftemperatur: T=35°C

friction moment variation in time

NUP212E

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

0,0

0,5

1,0

1,5

2,0

2,5

1000 1500 2000 2500 3000

n [min-1 ]M

ges

[Nm

]0,0

0,5

1,0

1,5

2,0

2,5

1000 1500 2000 2500 3000

n [min-1 ]

Mge

s[N

m]

Messung

Simulation

Messung Simulation

Simulation results (1)

- Zylinderrollenlager: NUP212E- Radiale Belastung Pr = 1430 N- Schmierstoff: ISO VG 100 (Referenzöl FVA 3)- Ölbadschmierung (Ölstandshöhe H=10mm)- Schmierstofftemperatur: T=35°C

Axialkraft Pa=443 N Axialkraft Pa=665 N

NUP212Emeasured friction moment and simulated friction moment

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Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

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• the evaluation of transient operation conditions in roller bearings are not treated by standard calculations

• Advanced tools for detailed investigations are available in the research departments of the leading manufactures and scientific Institutes, like the University of Kaiserslautern

Conclusion

Institute of Machine Elements, Gears, and Transmissions Prof. Dr.-Ing. B. Sauer

Address

Technische Universität Kaiserslautern

Lehrstuhl für Maschinenelemente und Getriebetechnik

Prof. Dr.-Ing. Bernd Sauer

Gottlieb-Daimler-Straße P. O. Box:Building 42 Postfach 3049D-67663 Kaiserslautern D-67653 Kaiserslautern

Phone: +49 (0) 631 205-2309 / -3405

Fax: +49 (0) 631 205-3716

E-Mail: megt@mv.uni-kl.de

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