© ZF Friedrichshafen AG, 2014 1 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
ZF Friedrichshafen AG
DTGS2
Carsten Stamm
MBS Roller Bearing Modeling
© ZF Friedrichshafen AG, 2014 2 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 3 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 4 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Roller Bearings in Transmissions
Roller bearing function:
• Keep shafts in place
• Interface between shafts and housing
(transfer of static and dynamic forces)
Influence of bearings:
• Noise
• Stiffness of whole system
Role of bearings in noise prediction:
• Lower frequencies (unbalance):
Bearing clearance
• Higher frequencies (gear meshing frequencies):
Misalignment of shafts (stiffness, clearance)
© ZF Friedrichshafen AG, 2014 5 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Motivation
Requested function of roller bearing force elements:
• Interaction between radial, axial forces, tilting moments and stiffnesses
• Fast
• Accurate
• Stable
Expected improvements in MBS models:
• Correct misalignments
• Correct gear excitation
• Correct transfer path to housing
• Correct stiffnesses, Eigenmodes
© ZF Friedrichshafen AG, 2014 6 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Roller Bearing Stiffness
Bearing stiffness calculation according to ISO/TS 16281 includes:
• Rollers: numbers, dimensions, shape, position
• Clearance
• Load
© ZF Friedrichshafen AG, 2014 7 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Tested Bearing Types
Stiffness maps:
3 dim 4 dim 5 dim
Fax, ß, g Fy, Fz, ß, g Fax, Fy, Fz, ß, g
x
y
d = 65
D = 120
Nof Rollers= 10
d = 100
D = 130
Nof Rollers= 37
d = 43
D = 59
Nof Rollers= 48
d = 51
D = 95
Nof Rollers= 16
Bearinx map files include correct geometry. Other methods with approximated geometry.
© ZF Friedrichshafen AG, 2014 8 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Testmodels and Result check
static + sweep 2) freefall with thrust bearing 1) Symmetric shaft bending
Static result check with ZF-Tool (deflections, torques, stiffnesses)
Dynamic check of Eigenmodes and resonance
g
© ZF Friedrichshafen AG, 2014 9 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 10 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Third Party Options in Simpack (Tested Force Elements)
FE Name radial axial bending clearance nonlinear comment usable
49 INA Bearinx
Roller Bearing
x x x x x Large map files (>200 MB)
No information about content
x
89 KissSoft
Roller Bearing
x x x x *) x Pre release x
UF25 Radial/Axial
Spring/Damper
x x x x ZF x
UF27 Stiffness map x x x x x ZF, modified FVA x
UF27 Hertzian Formula x x x ZF, modified FVA x
UF28 LAMBDA x x x x x FVA, at present only ball bearings x
*) clearance not available for needle roller bearing
© ZF Friedrichshafen AG, 2014 11 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Simpack Roller Bearing User Forces
ZF-UF25: linear stiffness, clearance, thrust forces with possible contact radius
ZF-UF27 Hertz: nonlinear stiffness with Hertz formula. No clearance, no tilting stiffness.
Based on FVA project DrespToSimpack
ZF-UF27 Map file: stiffnesses according to map file, created with ISO/TS 16281
Based on FVA project DrespToSimpack
FVA Lambda: modeling of inner bearing geometry and contact calculation.
Calculation of roller dynamic and cage possible
c
© ZF Friedrichshafen AG, 2014 12 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 13 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Ball Bearings dynamic
Load
10 µm (10%)
0.5 * clearance
© ZF Friedrichshafen AG, 2014 14 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 15 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Needle Roller Bearings dynamic
800 Hz
330 Hz
Load
?
© ZF Friedrichshafen AG, 2014 16 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 17 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Tapered Roller Bearings, static load
No clearance in bearing definition
Axial clearance in system
0.5 mm 0.5 mm
right side centered
left side displaced
© ZF Friedrichshafen AG, 2014 18 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Tapered Roller Bearings, dynamic load
© ZF Friedrichshafen AG, 2014 19 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 20 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Thrust Bearings
Testmodel: Tilted 3mm free fall
Bearinx failed! Worked only for distance<50µm
Clearance is not a property of thrust bearing (Unilateral springs) !
UF25 + KissSoft: Alignment perfect
UF27 Mapfile: Misalignment 5 mrad
© ZF Friedrichshafen AG, 2014 21 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 22 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Performance
Model description:
2 Bearings
1 Flexbody
Simulation time 2 s
Simpack V9.7
min
min
min
© ZF Friedrichshafen AG, 2014 23 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
Options in Simpack
Ball Bearings
Needle Roller Bearings
Tapered Roller Bearings
Thrust Bearings
Introduction
Performance
Conclusion
© ZF Friedrichshafen AG, 2014 24 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
Conclusion
Stiffness calculation in every time step (KissSoft):
Good results but slow (complete gearbox > 10 bearings, DoE)
Differences in needle roller bearing results are examined.
Map files (Bearinx, UF27):
Bearinx: Good performance but sometimes large map files. Correct geometry for INA bearings
UF27: More flexible than Bearinx, but not always accurate yet. Some improvements required.
Modeling of inner geometry (Lambda):
Not mandatory for stiffness calculation. Good for examination of bearing inner dynamics
Hertz Formula (UF27 Hertz):
Too fast and slick to ignore. Good for shafts without bending and pure radial load
Linear stiffness (UF25):
Fast. Good for shafts without bending.
Correct results require correct bearing geometry!
© ZF Friedrichshafen AG, 2014 25 2014-10-08 DTGS2, MBS Roller Bearing Modeling, Public
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