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MBS Simulation Techniques to Determine Spatial Load Distributions

and Torque Build-Up for Freewheel Clutches

Gerald Ochse

University Kassel, IAF/MT

Richard Schönen

IST GmbH Aachen

Carsten Träbing,

Volker Ploetz

Schaeffler Technologies

GmbH & Co. KG

SIMPACK User Meeting 2014

2



Content

• Problem Statement, Goal, Implementation

• Basis

• Contact Situation

• Force and Friction Models

• Freewheel Clutch

• Simulation

• Experiment

• Comparison

• Summary

3



Problem Statement

Need for:• Proper modeling of contact physics

• Consideration of global and local stiffness effects

• Analysis of components in complete systems in full interaction

Initial Situation:• Software tools for the dynamic simulation of multi body systems

(MBS) are available and well established

• Models for internal contact and transfer of loads may be:

• Either insufficient in terms of modeling contact mechanics

and/or

• Time-consuming in their application

4



Goals & Realization

Goals:• To establish time efficient methods and algorithms for contacts

in MBS systems

• To make available different physical models for frictional forces

• To fully implement in MBS simulation

• To support ease of use with a Graphical User Interface

Implementation:• Adequate contact algorithms were cast in external Fortran routines

• Integration in commercial MBS-Program by standardized interfaces

• Simple contact model for validation vs. existing internal routines

• Extension of contact and friction models to consider effects of

• Slip and sum velocities

• Lubricant parameters

• Surface roughness

5



Contact Situation

Approach and Overlap of two Rigid Bodies• are defined by

• Position

• Velocity

• Geometry

6



Force Models of the UFEL

Force Models:

• Spring-Damper

• DIN ISO 281

• Hertz elliptical

• Wijnant (extension Hertz by

lubrication)

FD x

e

F s c d vs

δ = ⋅ − ⋅

3

2

HZ 2

3

'

2RKF

3R 2

E

δ ⋅ ⋅

= κ

⋅ π

ε

ε

281

15 0.8 0.910 B

F3.97

δ ⋅ ⋅=

x

y

WIJ HZ

q(L)R

1 p(L) MR

= − ⋅ ⋅ ⋅

δ δ( ) ( )

( )

2 1x 3 3

y

WIJ 1

3hyd

g(L)

R4 f (L) M F R E '

Rd

6 K V

⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅

=

⋅ κ ⋅ ⋅

ε πɶ

Spring-Damper:

• Standard Contact

• Simpack Force 18

7



Friction Models of the UFEL

Friction Models:

• constant (static/dynamic)

• Drozdov / Gavrikov

• O‘Donoghue / Cameron

• Misharin

• Benedict & Kelly

• ISO / TC60

• external DLL

ODC 1 1 1 1

8 3 6 20 slide

S 220,6

35

V V RΣ

+⋅

µ =

η ⋅ ⋅ ⋅

( )0,25

MIS slide k0,325 V V−

Σµ = ⋅ ⋅ ⋅ν

0,25

TC6

0

W ' S0,12

R VΣ

⋅µ = ⋅

⋅ ⋅η

( )8

BUK 10 2

0 slide

3,17 10 W '500,0127 log

50 S V VΣ

⋅ ⋅ µ = ⋅ ⋅ ⋅ − η ⋅ ⋅

0.25

aDRG

cs m csgleit

1 R

0.63e 60.8 V V (p ; ) 13.4Σ

= ⋅

−⋅ ⋅ ν + ⋅Φ ν + µ

4 3

m cS0.47 0.13 10 p 0.4 10− −Φ = − ⋅ ⋅ − ⋅ ⋅ν

0.25

aDRG

cs m csslide

1 R

0.63e 60.8 V V (p ; ) 13.4Σ

= ⋅

− ⋅ ⋅ ν + ⋅Φ ν +µ

4 3

m cS0.47 0.13 10 p 0.4 10− −Φ = − ⋅ ⋅ − ⋅ ⋅ν

a

m

Parameters :

R ,S surface parameter

p hertzian pressure

W' specific line load

, viscosity

V surface velocity

R contact radius

ν η

statµ

µdyn

gleitv transv

statµ

µdyn

gleitv transvvslide vtrans

8



Examples of Freewheel-Clutches

Firmenschrift Ringspann GmbH, Bad Homburg, 2012

Feeder-Unit• material

Overrunning clutch• starter motor

Return stop• elevators

• conveyor band

9



Idling and Switching of a Freewheel Clutch

ωouter

ωinner

ωouter

ωinner

Idling Switching / Locking

11



MBS Freewheel: Elements, Force Coupling, DOF

Subsystem

Inner Race

Outer Race

Cage

Sprag

X

Y

Z

Main Model

Contact

Sprag / Outer Race

Contact

Sprag / Inner Race

Contact

Sprag / Cage

Torque-Momentum

Sprag / Cage

Force Coupling

rot.

rot.

rot.

trs. y

trs. z

DOF

12



MBS Freewheel: Elements, Force Coupling, DOF

• Single / multi area contact

• Force coupling

• 3D load distribution

• Eccentricity, misalignment

• Substituted stiffness of outer race

Inner Race

Outer Race

Cage

Sprag

X

Y

Z

Contact

Sprag / Outer Race

Contact

Sprag / Inner Race

Contact

Sprag / Cage

Torque-Momentum

Sprag / Cage

rot.

rot.

rot.

trs. y

trs. z

13



UFEL - GUI

• Create new or

• Modify existing contact

• Contact Marker From & To

are based on Marker 96

• Data Input

14



UFEL Disc Model

bϕ

R

ϕ

b

Disc Model• Discretisation of the contact in direction of width

• Gap and overlapping at skew position and crowning

gap gap andoverlapping

overlapping

15



MBS: Normal Force & Pressure Distribution

Angle

Skewing of the Outer Race

Intended Distribution

Crowned Sprag

Sp

rag

Wid

th [

mm

]S

pra

gW

idth

[m

m]

Sp

rag

Wid

th [

mm

]

3 Switch Cycles

3 Switch Cycles

3 Switch Cycles

Co

nta

ctFo

rce

[k

N]

3 Switch Cycles

AngleAngleAngle

16



Variation of Stiffness and Clearance

3 110c c= ⋅

2 10 5c . c= ⋅

⋅1100

Clearance : mm

2 2 5 8 N

mc . e= ⋅

17



Experimental Work

Frontside

Backside

• Freewheel:o Sprags with strain gaugeso at marked positions

18



Experimental Work

• Sprag with Strain Gauges at both sides

19



Experimental Work

• Calibration Unit• Continuous Force up to 10 kN

Sprag with

strain gaugeCalibration Unit

20



Flange Modification in Simulation & Experiment

Asymmetric Load Distribution• Reduced outer diameter

78 mm

70 mm

21



Flange Modification in Simulation & Experiment

Asymmetric Load Distribution• Reduced outer diameter

• Stiffening with a ring (SR) in the positions front, middle, rear

• Configuration for test rig and FE-Analysis

• Calculation of the substituted stiffness

70 mm,

SR front

70 mm,

SR middle

70 mm,

SR back

Contact zone sprag / flange

22



Distributed Load in the Experiment

70 mm,

SR front

70 mm,

SR middle

70 mm,

SR back

Asymmetric Load Distribution• Force measurement with strain gauges (SG) at the sprag

• Normal-Force in kN

SG back SG front

5,05

5,19

5,75

6,52

6,12

5,96

23



Freewheel with Lineload in the FE-Simulation

24



Displacement Results from FE-Analysis

SR backSR middleSR frontwithout SR

middle back

Width in mm

front

Dis

pla

cem

en

tin

mm

Displacement at 10 kN line load,variation of outer flange diameterand place of the stiffning ring (SR)

25



Comparison of Experiment and Simulation

Asymmetric Load Distribution• Stiffening ring in position front

• 3 contacts and substituded stiffness for flange

• Good agreement

• Difference 3-5%

fro

nt

mid

dle

ba

ck

3 contacts

hinten mittig vornefrontmiddleback

Forc

e i

n N

Experiment

Simulation

26



Summary

• Efficient methods and algorithms for modeling contact in MBS simulation

with different model depths have been implemented and validated

• 4 force models, 6 friction models and external DLL

• Parameters influencing the contact behaviour include

• Position, velocity, surface velocity, crowning, lubrication

• Width discretisation of compliances is considered by disc model (direct stiffness)

• Implementation into commercial MBS-Program Simpack was successfully validated

• Marginal increase of calculation time

• ca. 8% with 200 discs

• 1-2% with Wijnant instead of Hertz

• Additional Results

• Postprocessing in Simpack

• Data output in ASCII-Files (3D-representation, postprocessing)

27



Thanks to

FVA

Schaeffler Technologies

GmbH & Co. KG

IST

Simpack

AiF

AK-Freiläufe

28



Contact

Universität Kassel / University Kassel

Institut für Antriebs- und Fahrzeugtechnik /

Institute for Powertrain an Automotive Engineering

Maschinenelemente und Tribologie /

Chair for Machine Elements and Tribology

Prof. Dr.-Ing. Adrian Rienäcker

Mönchebergstr. 3

34125 Kassel

T: +49 (0)561 804-2774

F: +49 (0)561 804-3727

[email protected]

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