simulation m hods or nvh -d opm t of a oubl clutch ... · pdf filesimulation m hods or nvh -d...

Simulation Methods for NVH-Development of a Double Clutch

Transmission Gearbox

SIMPACK User Meeting 2014

Alexander Neubauer

Mercedes-Benz Cars Development

Daimler AG, Stuttgart

Alexander Neubauer | Daimler AG | 09 October 2014 2

Content of presentation

1. Gearbox Simulation in Driveline Developement

2. Overview Testrigmodels for NVH-Simulation and Methodology

3. Simulation of Gearwhining in the DCT Gearbox

4. Evaluation of Rattling Sensitivity of DCT Gearbox

5. Conclusion and Future Work

Vortrag Alexander Neubauer | DAIMLER AG, RD/FNP | 01.10.2014 3

3

Design Integration Design Matching

Big models, Low Discretisation

Low frequency range High frequency range

Compact models, High Discretisation

Simulationmodels - Design and Developement Driveline

1.1 Driveline Development - NVH Simulation

1.2 Overview of Noises in Automotive Gearboxes

Gearbox NoisesGearbox Noises

Loaded gearsLoaded gears

Gear whiningGear whining

Unloaded gearsUnloaded gears

Idle speedIdle speed Coast / Full loadCoast / Full load

RattlingRattling

source/reason:

• Fluctuation in stiffness (transmission error)

• Macrogeometry of gear (Spur bevel- and

Helix Gearwheel)

• Microgeometry (Gearteeth flank correction)

• High loadtorque (Pretension)

• Bending stiffness of the shafts

• Structural behavior of housing

• Oil viscosity and temperature

source/reason:

• Impulsive hits at the gear backlash limits

• Loose gear oscillation of unloaded gearwheels

(also synchrobodies) because of gear backlash

• Torsional vibration excitation of the driven gear

• Angular acceleration amplitude is responsible

for taking off loose gear from the driven flank

of the fix gear

• Oil viscosity and temperature


2.1 Methodology for NVH-Simulation of DCT Gearbox


SIMPACK- Pre SIMPACK-Post

• Taper roller bearings with

stiffness in 3D-Map from the

supplier (BEARINX-MAP)

• bearing properties from KISS-

SOFT interface (input from CAD)

0 1000 2000 3000Frequenz [Hz]

1000

1500

2000

2500

3000

3500

Drehzahl [1/min]

-50

-40

-30

-20

-10

0

10

20

Beschleunigung [dB/(m/s²)]

21 42

63KS1 Z

• Campbell plots for gear rattling

and whining

• 3D-map to descibe rattling

sensitivity of a gearbox for a

switched gear

• Creation of targets for stucture

borne sound level on defined

housing locations

• Operational mode shape

analysis of the gearbox housing

(excitation at bearing locations

with constant velocity)

• flexible gearbox housing

• modal materialdamping

• external nodes for evaluation of

structure borne sound

• rigid body elements for

gearshaft mounting

• flexible gearshafts

• switchable gears

• bearings with 6 DOF

• syncrobodies as dummy bodies

• rigid gearwheels with detailed

macro- and microgeometry

• gearwheels with material data

• analytical gearpair contact

simulation (ISO 6336)

1500 2000 2500 3000

Drehzahl [1/min]

-30

-20

-10

0

10

20

30


KS2 X

940 Hz

2700 min-1

570 Hz

1600 min-1

• transmission error

• eigenfrequency analysis

• Detailled analysis of mechanism

• correlation with end-of-line

testrig measurements

• Evaluation of accelerations on

defined housing locations

• detailed analysis of gearorders


DCT

Diff

Constant

Torque

velocity

at sideshaft

velocity

at sideshaft

DCT

Diff

Constant

Torque

Constant

Torque

Defining velocity with:

• Measured torsional excitation

• Sinusiodal excitation

��

�

2.2 Overview Testrig Models for NVH-Simulation

Targeting “whining“

Targeting “rattling“ 0 1000 2000 3000Frequenz [Hz]

1000

1500

2000

2500

3000

3500

Drehzahl [1/min]

-50

-40

-30

-20

-10

0

10

20


21 42

63KS1 Z

2nd gearcoast

Rattling Testrig Whining Testrig

Generat gearbox excitation

2.3 Simulation Workflow


SIMPACK Pre /Solving POST / Nastran

MBS-Simulation

Excitation from

GEAR-PAIR

+Dynamics from bending modes

of gearshafts

+Dynamic behaviour of gearbox

housing up to

6kHz

Transient excitation

forces

at shaft bearings

Export-script

transient excitation

F(t) from gear order

Frequency dependent

excitation

F(f) from gear order

(as RLOAD/DLOAD-

Table in NASTRAN)

FEM-simulation (NASTRAN)

operational mode shape

analysis

Evaluation housing

accelerations (in dB) on

defined housing locations in

gear order

MBS-simulation (SIMPACK)

Evaluation of response


Defining all boundary conditions (given speed at

sideshaft, torque at inputshaft) from DCT EOL

testrig in series production

n [rpm]

M [Nm]

3.1 Introduction to DCT Gearbox Simulation Model

DCT End-of-line (EOL) SIMPACK MBS-Model

Dre

hza

hl

Dre

hm

om

en

t

Coast

Full-load3500 to

1000 rpm

5,5 sec

from– 73 Nm

up to – 15 Nm

5,5 sec

from+ 16 Nm

up to+ 164 Nm

Operation Program EOL Testrig (one gear)

Rigid

Differential

Flexible

Side shaft

Gearset with

Rigid gears and

Flex shafts

Flexible

housing


3.2 Description of Gearset in DCT Gearbox Model

• Two part gearsets with flexible shafts

• Switchable gearstages and loose gears

• Definition of gearwheel Macro- and Microgeometry

• Analytical gearpair contact simulation (ISO 6336)

• Gearshaft bearings with 6 DOF

• Synchrobodies with dummys (mass & inertia)

• Rigid gearwheels with material properties (damping)

• Gear slicing for shifting of shaft and gearwheel

• Loss torque at each loose gear as damping value

• Taper roller bearings with 3D-maps for stiffness fromthe supplier (BEARINX-MAP)

• Bearing properties from KISS-SOFT interface (inputfrom CAD)

Contactmodelling with slicing

Topology of one gear stage

Input shaft loose gearfixed gear Output shaft

Force Element with Number Joint with 1 DOF about rot.axis

1500 2000 2500 3000

Drehzahl [1/min]

-30

-20

-10

0

10

20

30


1500 2000 2500 3000

Drehzahl [1/min]

-30

-20

-10

0

10

20

30


KS2 X KS3 X


3.3 Correlation End-of-line to Simulation

good correlation between measured housing

structure borne sound level in the gear order at the

end of line (EOL) testrig and in MBS-simulation

Measurement end of line (EOL)

Model with nonlinear bearing stiffness (FE43)

Model with 3D-Map (BEARINX)

DCT, coast, 2nd gear order


3.4 Mechanism of Gear Whining

NVH Problem:

Gear whining at coast in the gear order from

meshing between fixed and loose gear

2nd bending mode at 974 Hz (lateral bending)

with gearbox carrier resonance

1st bending mode at 607 Hz

Axial vibration of

inputshaft

bearing bed

560 HZ operational mode of housing

Mechanism:

Overlap gearmeshing with bending resonance of

both inputshafts (disadvantage in frequency of

gearpair with the teeth meshing frequency)

gear order

Gear order

940 Hz

2700 rpm570 Hz

1600 rpm

60dB

40dB

30dB

50dB

n [rpm]

Measurement at end-of-line

F [N]

L [dB]

Bearing forces simulation

F-X Inputshaft2 bearing

F-Y Outputshaft2 bearing


Housing acceleration end of line

Housing acceleration engine testrig

Good correlation between measured

structure borne sound level at gearbox

housing at end of line and engine

testrig and also the air borne sound

level in the vehicle at co driver seatS2

S2, Mot –X(orientation of

gearbox in vehicle –

lateral build in)

3.5 Correlation Vehicle and Testrig Measurements

Air borne sound level co-driver seat

1600 rpm2600 rpmCoast 2nd Gear

Gear order

End-of-line & Engine testrig

Vehicle measurement

1600 rpm 2600 rpm

S2, Fzg -Y

Gear order


3.6 Influence of Bending at Input shaft on Whining

Trail: Application of additional masses at inputshaft1 (solid shaft), for example130gr

on fixed gearwheels at two locations

Result MBS-Simulation Result End-of- line Testrig

Target: Shifting up/down of the bending eigenfrequencies from inputshaft 1, that the

first characteristic gear whining peak will decrease at 1600 rpm

-4 dBBaseline

Simulation

Changing mass at input shaft 1 has influence on

gear whining above all in lower engine speed

rpm

dB

rel. m

/s² Baseline

Measurement

-3 dB

dB

rel. m

/s²

rpm

Time [s]

Housing accelerations [dB]

velocity in [rpm] of

fixed gear

loose gear


4. Evaluation of Rattling Sensitivity of DCTImpacts on flank with backlash are responding as housing acceleration

peaks (sinusoidal torsional excitation at the gearbox inputshaft)

� Created 3D-map is only valid

for one gear and load, variation

of speed and angular excitation

� 3D-map is an important criteria

for rattle sensitivity of the DCT

gearbox

rattle limit


5. Conclusion and Future Work

0 1000 2000 3000Frequenz [Hz]

1000

1500

2000

2500

3000

3500

Drehzahl [1/min]

-50

-40

-30

-20

-10

0

10

20


21 42

63KS1 Z

• complex eMBS-modell necessary

• great influence of the transferpath from

– flexible shafts to housing

– bearing stiffnesses and damping

• Good correlation simulation to measurements

with non linearity bearing stiffnesses as 3D-

maps (BEARINX)

• gearrattling 3D-map for one gear and load

created

• further investigation for rattling sensitivity with

comparison of structure borne sound level on

housing with real engine excitation response

with DMF.

• Modelling of additional excitation mechansim

for example from the gearbox oil pump gear

meshingFull load run up of a gearbox in the 2nd gear with a real

engine excitation of a 4-Cylinder Dieselengine without

DMF, Torque at inputshaft 300 Nm

16

Thank you for your Attention!

Any questions…?

Thank you for your Attention!

Any questions…?

Alexander Neubauer | Daimler AG | 09 October 2014

simulation m hods or nvh -d opm t of a oubl clutch ... · pdf filesimulation m hods or nvh -d...

Documents