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Wolfgang SCHWARZ
AVL France
Public
POWERTRAIN NVH ANALYSIS
From Engine via Transmission to the Entire Drive Line
Wolfgang SCHWARZ | AST France | 20 février 2017 | 3Public
• Introduction
• Review of numerical analysis methods for powertrain NVH
• Root cause analysis – piston impact noise
• Transmission & driveline noise analysis
• NVH of electric & hybrid drive lines
• Conclusion & Outlook
CONTENT
Wolfgang SCHWARZ | AST France | 20 février 2017 | 4Public
INTRODUCTION AND MOTIVATIONNVH GENERATION AND TRANSFER PROCESS
0 200 400 600 800 1000 1200 1400 1600 1800 2000
2000
3000
4000
5000
6000
7000
0
10
20
30
40
50
60
70
Sporty
Powerful
Frequency - Hz
En
gin
e S
pee
d -
rp
m
Inte
rio
r N
ois
e L
evel
- d
BA
Frequency
En
gin
e S
peed
NVH is to a high extend subjective
Subjective
Assessment
(Customer)
Source /
Excitation
Mechanism
Amplification /
Damping,
Transfer
Response,
Result &
Assessment
Objective
Assessment
(Legislation)
Trade Offs with:
• Power Generation, Performance
• Fuel Consumption and Emissions
• Temperature and Thermal Management
• Packaging and Weight
• Durability
• Costs
• …Sporty
e.g. oil level / viscosityefficiency rattle!
Wolfgang SCHWARZ | AST France | 20 février 2017 | 5Public
Modern powertrain noise and vibration (NV) investigation in the development process or during trouble shooting is a combination of experimental and simulation investigations.
In simulation in recent years main focus was set on three major targets:
Model complexity and completeness for the target frequency range ( 0 to
3.5-5 kHz)
Consideration of all main excitation mechanisms and excitation sources (combustion, crank train, valve and timing drive, piston secondary motion, transmission noise, fuel system, auxiliary parts and drives, orifice noise, …)
Efficient and stabile numerical algorithms (FEM, MBD, BEM/iFEM/WBT, …)
By that, the total response of the virtual powertrain is already comparable to the overall noise level of the real powertrain (differences of local surface velocity levels in the range of 3 to 5 dB).
INTRODUCTIONNUMERICAL NV INVESTIGATION
Wolfgang SCHWARZ | AST France | 20 février 2017 | 6Public
NVH GENERATION AND TRANSFER PROCESS AND ROOT CAUSE DETECTION
Microphone position
structural response
Internal force path (transfer function)
Transfer
Source /
Excitation
Mechanism
Response
External force path / radiation (transfer
function)
Accelerometer position
excitation source , mechanisms and
driving parameters
Microphone array
radiated air
borne noise “What” is?
Target: “Why” and “How to improve”? Requires Link between Response,
Transfer and Source / Driving Parameters
Wolfgang SCHWARZ | AST France | 20 février 2017 | 7Public
• Introduction
• Review of numerical analysis methods for powertrain NVH
• Root cause analysis – piston impact noise
• Transmission & driveline noise analysis
• NVH of electric & hybrid drive lines
• Conclusion & Outlook
CONTENT
Wolfgang SCHWARZ | AST France | 20 février 2017 | 8Public
NVH MULTIBODY SIMULATION APPROACH
Characteristics
Elastic/rigid bodies interacting via non-linear joints
Vibrating, rotating and oscillating elastic structure parts represented by condensed FE models (CMS)
Various contact models up to highly complex thermo elasto-hydrodynamic joints including mixed lubrication
Non-linear transient forced vibration analysis in time domain
Excited by external forces
Typical number of master degrees-of-freedom (DOFs) 500 – 5.000 and much more in certain cases.
Gas Pressure
VT&TD Excitations
Piston Slap
Excitation Forces and Moments
Radial Slider Bearing,
Axial Thrust Bearing,
Piston / Liner Contact,
Rotational Coupling, ...
Nonlinear Bearing
Forces and Moments
calculated due to
Actual Dynamics of
Parts
Vibrating
Structure Parts
Vibrating, Rotating,
Oscillating PartsMBS solver
+ possibly other excitations coming from fuel injection system etc.
Wolfgang SCHWARZ | AST France | 20 février 2017 | 9Public
NVH ANALYSIS USING FEM AND MBS GENERAL WORKFLOW
CAD Data
Generation of FE Models for Separate Bodies
Verification of FE Models - Modal Analysis
Matrix Preparation (i.e. Condensation)
Reduced Stiffness and Mass Matrices
Dynamic Calculation with Multi-Body Solver Considering
all relevant Excitations for Entire Operating Range
Simulation with Condensed System
Durability Investigation
Calculation of Structural
Stresses
Evaluation of Motion Quantities
Extraction of Boundary Conditions for FEM Analysis
Durability
evaluation
FEM
Fatigue
Evaluation
MBS
Pre-
Processing
FEM
Structure borne
noise
Noise Radiation Evaluation
Calculation of Surface
Velocity Levels
Noise
Radiation
Vibrating and
moving
components
Vibrating
structures
Condensed
system
Noise
radiation
Joints and Connections
Wolfgang SCHWARZ | AST France | 20 février 2017 | 10Public
Comprehensive Simulation Model Fully elastic; oil film bearings
COMBUSTION NOISE- ROUGHNESS
NVH ANALYSIS - BASICS
EHD
bearings
All parts
flexible
Measured
Cylinder Pressure
Engine Mount
Dynamic StiffnessEngine Mount
Dynamic Stiffness
Engine Mount
Dynamic Stiffness
TVD Dynamic
Stiffness & DampingEHD
bearings
Wolfgang SCHWARZ | AST France | 20 février 2017 | 11Public
Powertrain NVH Assessment
Installation on powertrain test bed
Application of sensors
Close to main bearing (excitation correlation)
Engine surface (flexible part correlation)
Data acquisition
Data evaluation and comparison to simulation
NVH ANALYSISSIMULATION MODEL VERIFICATION
Wolfgang SCHWARZ | AST France | 20 février 2017 | 12Public
Sensor Position x, y, z
NVH ANALYSISSIMULATION MODEL VERIFICATION
Wolfgang SCHWARZ | AST France | 20 février 2017 | 13Public
Variety of methods exist:
Modal Contribution Analysis
Transfer Path Analysis
NVH Source Identification
NVH ANALYSISROOT CAUSE ANALYSIS
Cam cover
Wolfgang SCHWARZ | AST France | 20 février 2017 | 14Public
Target: Identification of the contribution of all main excitation mechanisms for certain regions and frequency ranges
Stepwise activation of different excitations
EXCITATION SOURCE RANKINGDETECT MAIN CONTRIBUTING EXCITATION
Excitation Level #1
Gas Force
Excitation Level #3
as #2 Timing Drive
added
Excitation Level #2
Gas Force,
Piston Slap
Wolfgang SCHWARZ | AST France | 20 février 2017 | 15Public
PERFORMANCE ATTRIBUTES (PA) DRIVEN DEVELOPMENT PROCESS AND TARGET SETTING
PA selection & target
definition
Results evaluation
Evaluation of PA
against the target
Status check & history review
Request design
change if PA target is not
achieved
Speed [rpm]
Acc
eler
atio
n [
g]
Target
Design progress
PA update
Virtual
Release
Wolfgang SCHWARZ | AST France | 20 février 2017 | 16Public
• Introduction
• Review of numerical analysis methods for powertrain NVH
• Root cause analysis – piston impact noise
• Transmission & driveline noise analysis
• NVH of electric & hybrid drive lines
• Conclusion & Outlook
CONTENT
Wolfgang SCHWARZ | AST France | 20 février 2017 | 17Public
Stroke
Lateral
Tilting
Axial
Rotation
Bending
EXAMPLE FOR PERFOMANCE ATTRIBUTEPISTON NOISE EXCITATION INDEX
Main driving parameters: Gas pressure, mass and inertia of
the piston, piston skirt geometry and stiffness, lubrication
condition between piston and liner, running clearance,
damping effect of the ring pack, pin and crankshaft offset
Primary Motion Secondary Motion Tertiary Motion
Wolfgang SCHWARZ | AST France | 20 février 2017 | 18Public
NUMERICAL INVESTIGATION IN PISTON NOISE
Measured or Pre-
calculated Transient
Gas Pressure
3D FEM
Piston
Measured Liner
Profile (Cold
Conditions)
Calculated
Thermal
Deviation
Frequency
Structural response on
Measurement Locations
(for Validation)
Acce
lera
tio
n
MBD ModelApproach:
• Multi-body dynamic
• Flexible structures for engine model and crank train
• 3D piston model
• Elasto-hydrodynamic piston-linear surface contact (mixed lubrication)
EHD piston-
linear contact
Piston Dynamics
and Impact
Analysis
Wolfgang SCHWARZ | AST France | 20 février 2017 | 19Public
RESULT EVALUATION OF SIMULATION AND EXPERIMENT
1496_Fiat_Piston_Slap_Time\1496_Fiat_Piston_Slap_KS Time 02.vas_fly Page - 1500 Time 100%thomanns - 25.07.2012 / 14:50:34
Project:
Measurement:
Testsite:
Condition:
FIAT PISTON SLAP (Giulietta 1.6 JTDM)
Structural Vibration Analysis
Acoustic Chassis Dynamometer
1500 rpm - 100 % Load
v122_1 Cylinder block lhs cyl. 4 top
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
Baseline Condition
v122_2 Cylinder block rhs cyl. 4 top v122_3 Cylinder block rhs cyl. 4 bottom
v122_4 Cylinder block rhs cyl. 3 mid
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
v122_5 Cylinder block rhs cyl. 3 bottom v122_6 Cylinder block lhs cyl. 3 mid
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e v122_7 Cylinder block lhs cyl. 3 bottom v122_9 Cylinder block lhs cyl. 3 top v122_10 Cylinder block lhs cyl. 3 l iner mid
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
0 120 240 360 480 600 720Crank Angle - deg
-900
-600
-300
0
300
600
900
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e v122_11 Cylinder block rhs cyl. 3 liner mid v122_12 Cylinder block lhs cyl. 4 l iner mid
0 120 240 360 480 600 720Crank Angle - deg
-900
-600
-300
0
300
600
900A
ccele
ratio
n - m/s²(Lin
ear)
Spitz
e
0 120 240 360 480 600 720Crank Angle - deg
0
3
6
9
12
Pre
ssure
- M
Pa(
Lin
ear)
Spitz
e
Cylinder 1
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ratio
n - m/s²(Lin
ear)
Spitz
e
31
32
33
3
4
41
42
Cyl #3 Cyl #4Cyl #3 Cyl #4
Root Cause Identification:
Evaluation of structural response
at identical positions
Development of a „piston slap
index“
Acce
lera
tio
n [m
/s2
]
Bad Good
I4 2500rpm / motored condition
Identical Evaluation Points
(Simulation (Approach #2) & Measurements)
Wolfgang SCHWARZ | AST France | 20 février 2017 | 20Public
PISTON NOISE EVALUATIONMETHODS AND INDICES
PNRI
Piston Noise
Response Index
General structure
borne noise
casescases
ExperimentSimulation / Approach
• Simulation of different piston variants (profile, clearance, pin offset) for various operating conditions
• EHD contact between piston skirt and liner
• Accelerations on outer engine surface up to 3.5 kHz considered
• Calculation of a Piston Noise Response Index (PNRI)
Wolfgang SCHWARZ | AST France | 20 février 2017 | 21Public
Crank Angle Based Piston Slap Evaluation of Filtered Vibration Signal
• Use direct acceleration signals, preferable taken from surface vibration in upper area of engine block
• Filter signal in frequency band 1 to 3.5 kHz
• Calculate rms value of filtered signal in critical time window (60° CA to 120° CA re firing TDC)
• This evaluation procedure is applicable for both, simulation and experiment in identical way, and therefore allows direct comparison.
definition of a „Piston Slap
Index“, characterizing piston
slap effect on engine noise
110501070
5010
toandto
to
SlapAccrms
AccrmsF
PISTON NOISE RESPONSE INDEX PNRI
Apply normalization
1496_Fiat_Piston_Slap_Time\1496_Fiat_Piston_Slap_KS Time 02.vas_fly Page - 1500 Time 100%thomanns - 25.07.2012 / 14:50:34
Project:
Measurement:
Testsite:
Condition:
FIAT PISTON SLAP (Giulietta 1.6 JTDM)
Structural Vibration Analysis
Acoustic Chassis Dynamometer
1500 rpm - 100 % Load
v122_1 Cylinder block lhs cyl. 4 top
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear)
Spitze
Baseline Condition
v122_2 Cylinder block rhs cyl. 4 top v122_3 Cylinder block rhs cyl. 4 bottom
v122_4 Cylinder block rhs cyl. 3 mid
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear )
Spitze
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear)
Spitze
v122_5 Cylinder block rhs cyl. 3 bottom v122_6 Cylinder block lhs cyl. 3 mid
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear)
Spitze
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear )
Spitze
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear)
Spitze v122_7 Cylinder block lhs cyl. 3 bottom v122_9 Cylinder block lhs cyl. 3 top v122_10 Cylinder block lhs cyl. 3 l iner mid
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear)
Spitze
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear )
Spitze
0 120 240 360 480 600 720Crank Angle - deg
-900
-600
-300
0
300
600
900
Accele
ration
- m/s²(Lin
ear)
Spitze v122_11 Cylinder block rhs cyl. 3 liner mid v122_12 Cylinder block lhs cyl. 4 l iner mid
0 120 240 360 480 600 720Crank Angle - deg
-900
-600
-300
0
300
600
900
Accele
ration
- m/s²(Lin
ear)
Spitze
0 120 240 360 480 600 720Crank Angle - deg
0
3
6
9
12
Pre
ssure
- M
Pa(
Lin
ear)
Spitze
Cylinder 1
0 120 240 360 480 600 720Crank Angle - deg
-600
-400
-200
0
200
400
600
Accele
ration
- m/s²(Lin
ear)
Spitze
Accele
ration
[m
/s2]
Isolate effect of other cylinders
Identify /
isolate piston
induced noise
index
Wolfgang SCHWARZ | AST France | 20 février 2017 | 22Public
0 (idle) 0.3 0.66 1 (WOT)
load
„noisy“
„silent“2500rpm
1000rpm
0 (idle) 0.3 0.66 1 (WOT)
load
1000rpm
PISTON NOISE RESPONSE INDEX PNRIEXAMPLE
Measurement Simulation
I4 Gasoline Engine 2.5 liters / 2 Design Variants:
Baseline (“noisy” piston)
„Silent“ low running clearance
Different load cases idle and part load
2 engine speeds
Warm engine condition (80degC CWT)
Good agreement
between simulation and
measurement
„noisy“
„silent“
2500rpm
1000rpm
2500rpm
2500rpm
1000rpm
Wolfgang SCHWARZ | AST France | 20 février 2017 | 23Public
• Introduction
• Review of numerical analysis methods for powertrain NVH
• Root cause analysis – piston impact noise
• Transmission & driveline noise analysis
• NVH of electric & hybrid drive lines
• Conclusion & Outlook
CONTENT
Wolfgang SCHWARZ | AST France | 20 février 2017 | 24Public
Main Applications
Gear Noise (Rattle, Whine,
Hammering)
Drive Line Vibrations
Low and High Frequency Effects
Stationary and Non-Stationary
Operating Conditions (Run-up, Tip-
in / Back-out, Clutch Activation)Frequency [Hz]
Shuffle
Clonk
Boom
Chatter
Rattle
Whine
Whoop
1 10 100 1000 10000
Shudder
Humming
Excitation Noise
Gear Whine
Prediction
Gear Rattle
Prediction
UNDERSTAND NVH-PHENOMENA IN TRANSMISSIONS AND DRIVE LINES
Wolfgang SCHWARZ | AST France | 20 février 2017 | 25Public
TYPICAL TRANSMISSION NVH PROBLEMS
Gear Rattle(unloaded gear rattle)
Gear Whine(singing, whistle)
Heartbeat Noise(harshness)
Engine-Transmission Interaction
Target: A common model approach depicting all phenomena
Wolfgang SCHWARZ | AST France | 20 février 2017 | 26Public
NVH SIMULATION OF TRANSMISSIONSGEAR RATTLE / DEFINITION AND CAUSE
Torque Flow
Loose gears
– unloaded
gears
Repeated impacts (contact change between driving/backlash flank) caused by movement of free parts (loose gears, synchronizer rings) within their active backlash
Important driver is torque fluctuation from engine
Moderate impacts result in a broad band excitation of the surrounding structures
Rattle
Gear Rattle
Wolfgang SCHWARZ | AST France | 20 février 2017 | 28Public
‚Rattle‘
Mdrag
ɪ
oil
Oil mist
Drag Torque / Oil Resistance
Torque Fluctuation
Housing FlexibilityShaft Flexibility
Roller Bearings
Damping in BacklashGear Contact Model
Backlash
EHL
Friction
Transfer
GEAR RATTLE - INFLUENCES AND REQUIREMENTS FOR SIMULATION
DMF
Torque Converter
Clutch
Pendulum Damper
Torque Isolation
Wolfgang SCHWARZ | AST France | 20 février 2017 | 29Public
GEAR RATTLE OF AN DIESEL ENGINE GEARBOX
Without Speed
Fluctuation
With Speed
Fluctuation
Gear Rattle
Measurements:
Measured with and without
speed fluctuations
influence on rattle clearly
visible
Simulation:
A calculated response at
gearbox housing shows
same speed and frequency
range where gear rattle
noise phenomena occurs
No gear whine noise since
tooth mesh stiffness
assumed as constant.
No gear rattle w/o
speed fluctuation
Wolfgang SCHWARZ | AST France | 20 février 2017 | 30Public
NVH SIMULATION OF TRANSMISSIONSGEAR WHINE / DEFINITION AND CAUSE
Torque Flow
Caused by periodic fluctuations in gear mesh (Transmission Error) due to
Geometrical insufficiencies (e.g. manufacturing inaccuracies, tolerances)
Elastic deflections under load
Manifested as a narrow banded, tonal noise at meshing frequency + harmonics and modulation
Engaged
gears
Gear Whine
mesh stiffness variation
number of teeth in contact
Wolfgang SCHWARZ | AST France | 20 février 2017 | 32Public
TRANSMISSION ACOUSTIC SIMULATIONGEAR WHINE
1st gear mesh order
2nd gear mesh order
(first harmonic)
fe
fe- fl
fl
Frequency
Vib
ratio
n fe+ fl
Main torsional frequency of crank
train (low order); e.g. 0-300Hz
Main meshing
frequencyModulated
frequencies
Manifested as a narrow banded (=tonal) noise
Engagement (main meshing) frequency (fe) +
Harmonics + Sidebands (modulation)
Annoying character
Critical when amplified by natural frequencies of
transferring / responding structures (e.g.
gearbox housing)
Wolfgang SCHWARZ | AST France | 20 février 2017 | 33Public
GEAR WHINEINFLUENCES AND REQUIREMENTS
‚Whine‘
edge loading
w/ lead crowning
Housing Flexibility
Shaft Flexibility
Roller Bearings
Friction
Transfer
Tooth Corrections and
Modifications
change of
backlash,
contact point
and contact
stiffness
Change of contact stiffness
Misalignment and
edge loading effects
Gear Contact Model
Full-elastic Gear Wheel Body
Real profile
3D Multi-flank contact
Wolfgang SCHWARZ | AST France | 20 février 2017 | 34Public
3rd
Gear
(z1/z2=36/45)
3000 rpm
1800Hz=
36th
Order
(1st meshing)
2nd
Order
(engine)
72th
Order
(2nd meshing)
1800 Hz = 36th Order
(1st meshing)
1800 Hz = 36th1785 Hz
1785 Hz
1815 Hz
1815 Hz
1800 Hz = 36th
1800 Hz =
1st Meshing
Order
Sideband
(36 + 2)th
Sideband
(36 – 2)th
GEAR WHINE TRANSFER - FROM GEAR MESH EXCITATION TO SOUND PRESSURE
Wolfgang SCHWARZ | AST France | 20 février 2017 | 35Public
Reduction transmissions of airplanes (e.g. turboprops)
Transmissions of trains (bogies)
Industrial and wind power transmissions
Axle transmissions (e.g. trucks, busses, construction)
Transmissions in electric drives
Picture reference: AVL or examples from internet
APPLICATION AREAS
The herein discussed approach and methodology are generic and applicable to all types of transmissions
Transmissions of tractors and construction equipment
Automotive – passenger car & trucks (MT, AMT, AT, DCT, CVT) & electrification
Simple two or multiple step transfer gear boxes
Wolfgang SCHWARZ | AST France | 20 février 2017 | 36Public
EXAMPLE TRANSMISSION NVHTRACTOR APPLICATION GEAR WHINE
Torque Flow
Simulation Model
MicrophonPosition
Dynamic Transmission Error
“bad”“good” – higher total nominal
Contact Ratio due to higher
overlap
dyn.
transm
issio
n e
rror
[mm
]
Mic 5
Mic 6
Wolfgang SCHWARZ | AST France | 20 février 2017 | 37Public
EXAMPLE TRANSMISSION NVHTRACTOR APPLICATION GEAR WHINE
Torque Flow
Simulation Model
MicrophonPosition
Dynamic Transmission Error
“bad”“good” – higher total nominal
Contact Ratio due to higher
overlap
dyn.
transm
issio
n e
rror
[mm
]
Mic 5
Mic 6
„SOL1 / good” „SOL 2 / bad”
SPL Sound Pressure Level [dB]
Wolfgang SCHWARZ | AST France | 20 février 2017 | 38Public
EXAMPLE TRANSMISSION NVHBUS REAR AXLE GEAR WHINE
Differential with
Hypoid Gear
Reduction at Side Shafts by
Planetary Gear Stages
Simulation Model
Wolfgang SCHWARZ | AST France | 20 février 2017 | 39Public
EXAMPLE TRANSMISSION NVHBUS REAR AXLE GEAR WHINE
Surface Velocity
Level [dB]
Sound Pressure
Level [dB]
1800 rpm / 3rd Octave Band 1250Hz Simulated Noise
Mic. 1
1m
Mic.1
1150 rpm
Mic.1
1800 rpm
Mic.1
2600 rpm
Gear whine
orders
Wolfgang SCHWARZ | AST France | 20 février 2017 | 40Public
• Introduction
• Review of numerical analysis methods for powertrain NVH
• Root cause analysis – piston impact noise
• Transmission & driveline noise analysis
• NVH of electric & hybrid drive lines
• Conclusion & Outlook
CONTENT
Wolfgang SCHWARZ | AST France | 20 février 2017 | 41Public
Simulation Model (Multi-body dynamics)
Max. Angle Motion
of Tensioner Arm
ΔF Fast-Slow
Fo
rce
[N
]
High Force
Time [s]Time [s]
An
gle
[d
eg
]BELT DRIVEN STARTER-GENERATOR (BSG)BELT DYNAMICS DURING ENGINE START
Wheel
WheelSA
GearbxEngine
Durability Issues at
Crankshaft Front End
Time [s]
To
rqu
e [
Nm
]
Starter-Alternator Torque
Different Start-Ramps
Wolfgang SCHWARZ | AST France | 20 février 2017 | 42Public
FULL ELECTRIC DRIVELINEELECTRICAL AND MECHANICAL NOISE
Wolfgang SCHWARZ | AST France | 20 février 2017 | 43Public
ELECTRO-MAGNETIC EXCITATION AND TRANSFER TO MECHANICAL SYSTEM
FEM magnetic fieldRadial, tangential & bearing
forces mapped to FEM
(frequency domain).
Ripple torque Multi-body Dynamic
Driveline, whine, etc.
Export excitation in
frequency domain
Coupled simulation excitations
in frequency domain (forced
response analysis)
Torque and bearing forces to MBS,
calculate eccentricity
Ele
ctr
ical N
ois
e
Mech
an
ical N
ois
e
PWM Harmonics
0
-20
-40
-60
20
40
60
Isa Isb Isc
0.3 0.32 0.34 0.36 0.38 0.4
Time (s)
0
20
40
60
80
100
Tem_IM4
Electrical + Mechanical
Wolfgang SCHWARZ | AST France | 20 février 2017 | 44Public
Electromagnetic excitation Electromagnetic excitation
+ Mechanical
ELECTRICAL AND MECHANICAL NOISE OF FULL ELECTRIC DRIVELINE
Wolfgang SCHWARZ | AST France | 20 février 2017 | 45Public
• Introduction
• Review of numerical analysis methods for powertrain NVH
• Root cause analysis – piston impact noise
• Transmission & driveline noise analysis
• NVH of electric & hybrid drive lines
• Conclusion & Outlook
CONTENT
Wolfgang SCHWARZ | AST France | 20 février 2017 | 46Public
• Complete powertrain models can be used in early development phase to predict complex NVH phenomena
• Simulation of the entire acoustic function chain with detailed physics provides the ability to understand cause and effect
The importance of considering and simulating transmission NVH within the entire development process increases by new requirements for efficiency and electrification
For many phenomena, it is important to consider transmission NVH simulation also in conjunction with the engine and powertrain
SUMMARY AND OUTLOOK
Further potential can be found in:
Further refinement of the models (e.g. damping, synchronization / shifting maneuvers, beveloid-and hypoid gears) and increase accuracy
Electro-mechanical interaction - effect of magnetic excitation and control
Acceleration of the process lead time
Extend and enhance interaction and combination with measurements (e.g. interior noise prediction)
Meaningful assessment and subjective evaluation directly from the simulation
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