Slide 1
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
SAE 2011 NVH ConferenceStructure Borne NVH Workshop
Presenters:
Alan DuncanAlan Duncan Altair Engineering @ Honda
Greg Greg GoetchiusGoetchius Tesla Motors
KiranKiran GovindswamyGovindswamy FEV Inc.FEV Inc.
JianminJianmin Guan Guan Altair Engineering
Contact Email: [email protected]: www.autoanalytics.com
Slide 2
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH WorkshopWorkshop Objectives -1. Review Basic Concepts of Automotive Structure Borne Noise.
2. Propose Generic Targets.
3. Present Real World Application Example.
Intended Audience –• New NVH Engineers.
• “Acoustics” Engineers seeking new perspective.
• “Seasoned Veterans” seeking to brush up skills.
Slide 3
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks
Slide 4
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks
Greg Goetchius
Slide 5
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks
Slide 6
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Rideand
Handling
NVH Durability
ImpactCrashWorthiness
Competing Vehicle Design Disciplines
Slide 7
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne Noise and Vibration
VibratingSource
Frequency Range: up to 1000 HzSystem Characterization
• Source of Excitation• Transmission through Structural Paths • “Felt” as Vibration• “Heard” as Noise
Slide 8
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NoiseAirborne Noise
Res
pons
e
Log Frequency
“Low”Global Stiffness
“Mid”
Local Stiffness+
Damping
“High”
Absorption+
Mass+
Sealing+
Damping
~ 150 Hz ~ 1000 Hz ~ 10,000 Hz
Automotive NVH Frequency Range
Slide 9
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
•Vehicle Interior Noise Simulation•NVH Principles: Applications
• Closing Remarks
Slide 10
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 11
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 12
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
RECEIVER
PATH
SOURCE
Structure Borne NVH Basics
Slide 13
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 14
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
m
APPLIED FORCE
F = FO sin 2 π f t
k c FT
TR = FT / F
TransmittedForce
Single Degree of Freedom Vibration
= fraction of critical damping
fn = natural frequency
f = operating frequency
( )2n
22n
2
2n
ff2)ff(1)ff(21ζ
ζ+−
+=
ζmk
Slide 15
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
0 1 2 3 4 50
1
2
3
4Tr
ansm
issi
bilit
y R
atio
1.414Frequency Ratio (f / fn)
Vibration Isolation Principle
m
APPLIED FORCEF = FO sin 2 π f t
k c FT
TR = FT / F
TransmittedForce
Isolation RegionIsolation Region
1.00.5
0.375
0.25
0.15
0.1
Slide 16
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 17
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Two Main Sources
NVH Source Considerations
Suspension Powertrain
Slide 18
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Typical NVH Pathways to the Passenger
PATHS FOR
STRUCTURE BORNE
NVH
Slide 19
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Sources
Slide 20
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Sources
Primary Consideration:
Reduce the Source first as much as possible because whatever enters the structure is transmitted through multiple paths to the receiver.
Transmission through multiple paths is more subject to variability.
Slide 21
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 22
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Receiver ConsiderationsSubjective to Objective Conversions
Subjective NVH Ratings are typically based on a 10 Point Scale resulting from Ride Testing
A 2 ≈≈≈≈ 1/2 A 1Represents 1.0 Rating Change
TACTILE: 50% reduction in motion
SOUND : 6.dB reduction in sound pressure level ( long standing rule of thumb )
Receiver Sensitivity is a Key Consideration
Slide 23
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 24
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Total 2178.2 Kg (4800LBS)Mass Sprung 1996.7 Kg
Unsprung 181.5 Kg (8.33% of Total)Powertrain 181.5 Kg
Tires 350.3 N/mmKF 43.8 N/mmKR 63.1 N /mmBeam mass lumped on grids like a beam M2,3,4 =2 * M1,5
Symbolic Model of Unibody Passenger Car8 Degrees of Freedom
From Reference 6
318
2
6
4
75
Slide 25
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
1 2 4 5
6 7
8
3
TiresWheels
SuspensionSprings
Engine Mass
EngineIsolator
Flexible Beam for Body
8 Degree of Freedom Vehicle NVH Model
Slide 26
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
8 Degree of Freedom Vehicle NVH ModelForce Applied to Powertrain Assembly
Forces at Powertrain could represent a First OrderRotating Imbalance
Feng
1 2 4 5
6 7
8
3
Slide 27
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Engine Isolation Example
Response at Mid Car
0.0001
0.0010
0.0100
0.1000
1.0000
5.0 10.0 15.0 20.0Frequency Hz
Velo
city
(mm
/sec
)
Constant Force Load; F ~ A 15.9 Hz8.5 Hz7.0 Hz
700 Min. RPM First Order UnbalanceOperation Range of Interest
318
2
6
4
753311
8822
66
44
7755
Slide 28
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Concepts for Increased Isolation“Double” isolation is the typical strategy for further improving isolation of a given vehicle design.
Subframe is Intermediate Structure
Suspension Bushing is first level
Second Level of Isolation is at Subframe
to Body Mount
Slide 29
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
8 Degree of Freedom Vehicle NVH ModelRemoved Double Isolation Effect
WheelMass
Removed
1 2 4 5
6 7
8
3
Slide 30
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Double Isolation ExampleVertical Response at DOF3
0.0E+00
1.0E+00
2.0E+00
3.0E+00
4.0E+00
5.0E+00
6.0E+00
5.0 10.0 15.0 20.0Frequency Hz
Velo
city
(m
m/s
ec)
Base Model
Without Double_ISO
1.414*fn
318
2
6
4
753311
8822
66
44
7755
Slide 31
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 32
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Mode Management Chart
0 5 10 15 20 25 30 35 40 45 50HzFirst Order Wheel/Tire Unbalance V8 Idle
Hot - Cold
EXCITATION SOURCESInherent Excitations (General Road Spectrum, Reciprocating Unbalance, Gas Torque, etc.)Process Variation Excitations (Engine, Driveline, Accessory, Wheel/Tire Unbalances)
Hz
Hz0 5 10 15 20 25 30 35 40 45 50
0 5 10 15 20 25 30 35 40 45 50
CHASSIS/POWERTRAIN MODES
Ride ModesPowertrain Modes
Suspension Hop and Tramp ModesSuspension Longitudinal Modes
Exhaust Modes
BODY/ACOUSTIC MODES
Body First Bending First Acoustic Mode
Steering Column First Vertical BendingBody First Torsion
(See Ref. 1)
Slide 33
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
8 Degree of Freedom Vehicle NVH ModelBending Mode Frequency Separation
Beam Stiffness was adjusted to align Bending
Frequency with Suspension Modes and then
progressively separated back to Baseline.
1 2 4 5
6 7
8
3
Slide 34
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Response at Mid Car
0.10
1.00
10.00
100.00
5 10 15 20Frequency Hz
Velo
city
(mm
/sec
)
18.2 Hz Bending13.Hz Bending10.6 Bending
8 DOF Mode Separation Example
18.2 Hz13.0 Hz
10.6 Hz318
2
6
4
753311
8822
66
44
7755
Slide 35
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 36
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Front input forces Rear input forces
First Bending: Nodal Point Mounting ExampleMount at Nodal Point
Locate wheel centers at node points of the first bending modeshapeto prevent excitation coming from suspension input motion.
Slide 37
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Passenger sits at node point for First Torsion.
Side View
First Torsion: Nodal Point Mounting ExamplesMount at Nodal Point
Transmission Mount of a3 Mount N-S P/T is nearthe Torsion Node.
Rear View
Engine
Slide 38
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Powertrain Bending Mode Nodal Mounting
Mount system is placed to support Powertrain at the Nodal Locations of the First order Bending Mode. Best compromise with Plan View nodes should also be considered.
1 2 4 5
6 7
3
Slide 39
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
1 2 4 5
6 7
8
3
8 Degree of Freedom Vehicle NVH ModelBending Node Alignment with Wheel Centers
Redistribute Beam Masses to move Node Points to
Align with points 2 and 4
Slide 40
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Response at Mid-Car
0.0E+00
1.0E+00
2.0E+00
3.0E+00
4.0E+00
5.0 10.0 15.0 20.0Frequency Hz
Velo
city
(m
m/s
ec)
Node ShiftedBase Model
First Bending Nodal Point Alignment
318
2
6
4
753311
8822
66
44
7755
Slide 41
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 42
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
YO
xSDOF
Dynamic Absorber Concept
MYO
x
Auxiliary Spring-Mass-Damperm = M / 10
2DOFM
Slide 43
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Powertrain Example of Dynamic Absorber
Anti-Node Identifiedat end of Powerplant
k c
Absorber attached at anti-node acting in the Vertical and Lateral plane.
Tuning Frequency = √√√√ k/m
m
[Figure Courtesy of DaimlerChrysler Corporation][Figure Courtesy of DaimlerChrysler Corporation][Figure Courtesy of DaimlerChrysler Corporation][Figure Courtesy of DaimlerChrysler Corporation]
Slide 44
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Baseline Sound Level63 Hz Dynamic Absorber63 + 110 Hz Absorbers
Baseline Sound Level63 Hz Dynamic Absorber63 + 110 Hz Absorbers
[Figure Courtesy of DaimlerChrysler Corporation][Figure Courtesy of DaimlerChrysler Corporation][Figure Courtesy of DaimlerChrysler Corporation][Figure Courtesy of DaimlerChrysler Corporation]
10 dB
Slide 45
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Low Frequency Basics - Review• Source-Path-Receiver Concept• Single DOF System Vibration• NVH Source Considerations• Receiver Considerations• Vibration Attenuation Strategies
Provide Improved IsolationMode ManagementNodal Point MountingDynamic Absorbers
Slide 46
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks
Alan Duncan
Slide 47
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Mid Frequency NVH Fundamentals
This looks familiar!Frequency Range of Interest has changed to
150 Hz to 1000 Hz
Slide 48
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Typical NVH Pathways to the Passenger
Noise Paths are thesame as Low
Frequency Region
Noise Paths are thesame as Low
Frequency Region
PATHS FOR
STRUCTURE BORNE
NVH
Slide 49
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Mid-Frequency Analysis CharacterStructure Borne Noise
Airborne Noise
Res
pons
e
Log Frequency“Low”
Global Stiffness“Mid”
Local Stiffness+
Damping
“High”
Absorption+
Mass+
Sealing
~ 150 Hz ~ 1000 Hz ~ 10,000 Hz
High modal densityand coupling in
source, path andreceiver
• Mode separation is less practical inmid-frequency
• New Strategy is Effective Isolation:Achieved by reducing energy transferlocally between source and receiver atkey paths.
•• Mode separation is less practical inMode separation is less practical inmidmid--frequencyfrequency
•• New Strategy is Effective Isolation:New Strategy is Effective Isolation:Achieved by reducing energy transferAchieved by reducing energy transferlocally between source and receiver atlocally between source and receiver atkey paths.key paths.
Slide 50
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Control Measures for Mid Frequency Concerns
Effective Isolation
Attenuation along Key Noise Paths
Mid-Frequency Analysis Character
Slide 51
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Control Measures for Mid Frequency Concerns
Effective Isolation
Attenuation along Key Noise Paths
Mid-Frequency Analysis Character
Slide 52
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Classical SDOF: Rigid Source and Receiver
T ran
smis
sib i
lity
Rat
io
1.0 1.414 10.0
f / f n
Isolation Effectiveness
Effectiveness deviates from the classical development as resonances occur in the receiver structure and in the foundation of the source.
Isolation RegionIsolation Region
1.0 “Real Structure”Flexible (Mobile)
Source and Receiver
Slide 53
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Mobility• Mobility is the ratio of velocity response at the excitation point on structure
to the force applied in the direction of the velocity
Mobility =Velocity
Force
• Mobility, also called Admittance, characterizes Dynamic Stiffness of the structure at load application point
Mobility =Frequency * Displacement
Force
=Frequency
Dynamic Stiffness
Slide 54
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
• Transmissibility Ratio (TR) is used to objectively define measure of isolation
TR =Force from source without isolator
Force from source with isolator
Isolation
V r
V ir
V is
F rF ir
Receiver
Source
F is
Fs V s
Isolator
VF s=
Y i + Y r + Y s
V r
F r
Receiver
Source
F s V s
VF s=
Y r + Y s
VV
• The isolation effectiveness can be quantified by a theoretical model based on analysis of the SOURCE - PATH - RECEIVER transfer across an isolator
Slide 55
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
TR = ( Y r + Y s ) //// ( Y i + Y r + Y s )
• For Effective Isolation (Low TR) the Isolator Mobility must exceed the sum of the Source and Receiver Mobilities.
Y r : Receiver mobility
Y s : Source mobility
Y i : Isolator mobility
V m
V im
V if
F mF im
Receiver
Source
F if
F f V f
Isolator
TR = Force from source without an isolator Force from source with an isolator
Isolation
Recall that K 1Y ∝
Slide 56
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
TR = ( ) //// ( ) K body
1K source
1+ K body
1 + K iso
1K source
1+
K iso
K sourceK body
K iso1.0 5.0 20.0
1.0
5.0
20.0
0.67 0.55 0.51
0.55 0.29 0.20
0.51 0.20 0.09
Generic targets:body to bushing stiffness ratio of at least 5.0source to bushing stiffness ratio of at least 20.0
Designing Noise Paths
Slide 57
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Stiffness Ratio; K body / K iso
Tran
smis
sibi
lity
Rat
io T
RBody-to-Bushing Stiffness RatioRelationship to Transmissibility
0
0.1
0.2
0.3
0.4
0.5
0.6
1 2 3 4 5 6 7 8 9 10
Target Min. = 5 gives TR = .20
For a source ratio of 20
Slide 58
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Control Measures for Mid Frequency Concerns
Effective Isolation
Attenuation along Key Noise Paths
Mid-Frequency Analysis Character
Slide 59
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Identifying Key NVH PathsKey NVH paths are identified by Transfer Path Analysis (TPA)
Fi
AcousticTransfer
AcousticTransfer
Operating loads Operating loads
Break the system at the points where the forces enter the body (Receiver)
Total Acoustic Response is summation of partial responses over all noise paths
Pt = ΣΣΣΣ paths [Pi ] = ΣΣΣΣ paths [ (P/F) i * Fi ]
Slide 60
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Designing Noise Paths
Fi
Acoustic Transfer (P/F)iAcoustic Transfer (P/F)i
Operating loads createForces (Fi) into body atAll noise paths
F FF F
FF F
Pt = ΣΣΣΣ paths [Pi ] = ΣΣΣΣ paths [ Fi * (P/F) i ]
P/F
Measurement Parameters Generic Targets
P/F Acoustic Sensitivity 50 - 60 dBL/N
V/F Structural Point Mobility (Receiver Side)
0.2 to 0.3 mm/sec/N
P/V
(Kbody)V/F
= ΣΣΣΣ paths [ Fi * (P/V) i * (V/F) i ]
Slide 61
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Recall for Acoustic Response Pt
Pt = ΣΣΣΣ paths [Pi ] = ΣΣΣΣ paths [ Fi * (P/V) i * (V/F) i ]
“Downstream” Effects: Body Panels
(P/V)i !!!! “Downstream” Dynamics (Body Panel) : Three Typical Effects:
3. Panel Acoustic Contribution
Increased Damping
2. Panel Damping
Increased Stiffness
1. Panel Stiffness
Slide 62
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Generic Noise Path Targets
K iso
K body> 5.0
K iso
K source
> 20.0
AcousticSensitivity < 50 - 60
dBL/N
StructuralMobility < 0.2 to 0.3 mm/sec/N
Panel Damping Loss Factor> .10
Primary: Minimize the Source Force< 1.0 N
Slide 63
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Final Remarks on Mid Frequency Analysis
• Effective isolation at dominant noise paths is critical• Effective isolation at dominant noise paths is critical
• Reduced mobilities at body & source and softenedbushing are key for effective isolation
• Reduced mobilities at body & source and softenedbushing are key for effective isolation
• Other means of dealing with high levels of response(Tuned dampers, damping treatments, isolatorplacement at nodal locations) are also effective
• Other means of dealing with high levels of response(Tuned dampers, damping treatments, isolatorplacement at nodal locations) are also effective
• Mode Separation remains a valid strategy as modesin the source structure start to participate
• Mode Separation remains a valid strategy as modesin the source structure start to participate
Slide 64
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks
Greg Goetchius
Slide 65
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Toolbox Demo Noise Test Results
85
61
68
63
55
47
39
30
40
50
60
70
80
90
1) Baseline:Imbalance, No
Isolation
2) Imbalance +Isolation
3) No Imbalance,No Isolation
4) No Imbalance,No Isolation +
Damping
5) No Imbalance +Isolation +Damping
6) #5 + Absorption 7) #6 + InsulatorMat
SPL
(dB
A)
Tool Box Demo Test Results
Slide 66
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks
Kiran Govindswamy
Slide 67
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
“Time Domain” Transfer Path Analysis
Excitation
Airb
orne
Pat
h
Interior Noise
Power Train NoiseIntake&Exhaust Noise. . .
Power Train VibrationDrive Line Vibration. . .
Transfer Behaviour
Microphones
Loudspeaker
FEVFEV
Pi
Overall Vehicle Transfer Function
Engine Mount Vehicle
Stru
ctur
e-Bo
rne P
ath
Airborne Noise Share
StructureborneNoise Share
Overall Interior Noise
Excitation
Airb
orne
Pat
h
Interior Noise
Power Train NoiseIntake&Exhaust Noise. . .
Power Train VibrationDrive Line Vibration. . .
Transfer Behaviour
Microphones
Loudspeaker
FEVFEV
Microphones
Loudspeaker
FEVFEV
Microphones
Loudspeaker
FEVFEV
Loudspeaker
FEVFEV
Pi
Overall Vehicle Transfer Function
Engine Mount Vehicle
Stru
ctur
e-Bo
rne P
ath
Airborne Noise Share
StructureborneNoise Share
Overall Interior Noise
VINS (Vehicle Interior Noise Simulation)VINS (Vehicle Interior Noise Simulation)
Slide 68
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
“Time Domain” Transfer Path AnalysisVINS (Vehicle Interior Noise Simulation)VINS (Vehicle Interior Noise Simulation)
Engine Excitation
ae ab
MountTransmissibility
Vehicle Body
Fb
Apparent Massof Body
Resultant Dynamic Mount Stiffness
Overall Structure-Borne Sound Transmission
abody
aengine
Fbody
abody
Pinterior
Fbody
aengine P= interior
Resultant Dynamic Mount Stiffness
Test Bench Impact Test
Slide 69
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
“Time Domain” Transfer Path AnalysisVINS: Correlation (Full Load Speed Sweep)VINS: Correlation (Full Load Speed Sweep)
Slide 70
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
“Time Domain” Transfer Path AnalysisVINS: Application to “Idle Modulation Noise”VINS: Application to “Idle Modulation Noise”
Slide 71
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
“Time Domain” Transfer Path AnalysisVINS: Application to “Idle Modulation Noise”VINS: Application to “Idle Modulation Noise”
Slide 72
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
“Time Domain” Transfer Path Analysis
Measurement VINS VINS-SBN VINS-ABN
VINS: Application to “Transient Diesel Clatter”VINS: Application to “Transient Diesel Clatter”
Slide 73
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
“Time Domain” Transfer Path Analysis
Mic. left Mic. right Mic. top Mic. bottom Mic. front Mic. rear Intake orif. Exhaust tp.
Left mnt. Right mnt. RR A RR B Trans.link
VINS: Application to “Transient Diesel Clatter”VINS: Application to “Transient Diesel Clatter”
Slide 74
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Start/StopICE
RegenerationBatt. Charging
AERPowerAssist
Start &idle
Drive-away
Acceleration
Constantspeeds
Coasting
ICE idling
CE
F D
AB
DF
D C
D CD C
AB
DF
DC
AB
AB
F
Red light (Stop) AE
ICE stopped
G
G
G
Start/StopICE
RegenerationBatt. Charging
AERPowerAssist
Start &idle
Drive-away
Acceleration
Constantspeeds
Coasting
ICE idling
CE
F D
AB
DF
D C
D CD C
AB
DFF
DC
AB
AAB
F
Red light (Stop) AE
ICE stopped
G
G
G
• A: Global powertrain vibration B: Driveline vibration• C: Noise of HEV specific components D: Magnetic noise E-Motor/(Generator)• E: Noise of accessories F: Gearbox rattle noise due to • G: Noise pattern changeover ICE (non-uniformity) and E-Motor
HEV, PHEV, ReEV, and EV NVH
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks Jianmin Guan
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
NVH Principles: Application Example Introduction
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Quietness during Idle and Electric-Vehicle Operation
Reduce Inverter Water Pump Loads:
1. Reduce pump impeller imbalance2. Redesign bearing structure3. Changing motor structure
Improve Isolation from Body:
1. Install rubber isolator2. Increase mounting bracket rigidity3. Improve Inverter case
Root Cause Diagnostics:
1. Water pump in the inverter cooling system2. Electromagnetic noise of the motor,
the inverter, and other units
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Quietness during Idle and Electric-Vehicle Operation
Reduce Inverter Water Pump Loads:
1. Reduce pump impeller imbalance2. Redesign bearing structure3. Changing motor structure
Improve Isolation from Body:
1. Install rubber isolator2. Increase mounting bracket rigidity3. Improve Inverter case
Root Cause Diagnostics:
1. Water pump in the inverter cooling system2. Electromagnetic noise of the motor,
the inverter, and other units
Reduce Source
EffectiveIsolation
Attach.Stiffness
Downstream
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Engine Start Vibration
Reduce Effect of Engine Loads:
1. Operating MG1 at high torque during engine start2. Implement vibration-reducing motor control3. Use two stage hysteretic torsional damper4. Shorten distance between principal elastic
axis and center of gravity of power plant
Root Cause Diagnostics:
1. Engine torque fluctuations2. Engine torque reaction forces
Reduce Torque Fluctuation:
1. Change intake valve closing timing2. Control piston stop position3. Adjust injected fuel volume and
ignition timing
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Engine Start Vibration
Reduce Effect of Engine Loads:
1. Operating MG1 at high torque during engine start2. Implement vibration-reducing motor control3. Use two stage hysteretic torsional damper4. Shorten distance between principal elastic
axis and center of gravity of power plant
Root Cause Diagnostics:
1. Engine torque fluctuations2. Engine torque reaction forces
Reduce Torque Fluctuation:
1. Change intake valve closing timing2. Control piston stop position3. Adjust injected fuel volume and
ignition timingReduce Source
Mode Manage.
Damper
EffectiveIsolation
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
2nd Order Engine Induced Boom
Root Cause Diagnostics:
1. 2nd order couple of the reciprocating inertia of piston2. THS II Trans 50 mm longer and 35 kg heavier3. Lower power plant bending mode4. Requires 1.5X higher mount rates
Reduce Effect of 2nd order Couple:
1. Increase power plant bending mode2. Move mount to a nodal point3. Embed mounts inside cross member4. Reduces distance from principle
elastic axis to CG 5. Optimized vertical to lateral rate ratio
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
2nd Order Engine Induced Boom
Root Cause Diagnostics:
1. 2nd order couple of the reciprocating inertia of piston2. THS II Trans 50 mm longer and 35 kg heavier3. Lower power plant bending mode4. Requires 1.5X higher mount rates
Reduce Effect of 2nd order Couple:
1. Increase power plant bending mode2. Move mount to a nodal point3. Embed mounts inside cross member4. Reduces distance from principle
elastic axis to CG 5. Optimized vertical to lateral rate ratio
Mode Manage.
Nodal Mounting
EffectiveIsolation
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Engine Radiated Noise
Reduce Effect of 24th order Loads:
1. Modified Trans case to improve modes2. Added dynamic damper at a high amp. point
on Trans case3. Added ribs in high radiating area of Trans case
Root Cause Diagnostics:
1. 24th MG2 order excitation2. Lower MG2 reduction gear ratio3. Lower transmission bending mode
- two key modes identified
Reduce 24th order Loads:
Arranged permanent magnets in V shape with optimized angle
Copyright © 2009 SAE International
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Engine Radiated Noise
Reduce Effect of 24th order Loads:
1. Modified Trans case to improve modes2. Added dynamic damper at a high amp. point
on Trans case3. Added ribs in high radiating area of Trans case
Root Cause Diagnostics:
1. 24th MG2 order excitation2. Lower MG2 reduction gear ratio3. Lower transmission bending mode
- two key modes identified
Reduce 24th order Loads:
Arranged permanent magnets in V shape with optimized angle
Mode Manage.
Reduce Source
Damper
Downstream
Copyright © 2009 SAE International
Slide 85
2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH Workshop• Introduction• Low Frequency Basics• Mid Frequency Basics• Live Noise Attenuation Demo• Case Studies
• Interior Noise Diagnosis using VINS•NVH Principles: Applications
• Closing Remarks Jianmin Guan
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Structure Borne NVH: Concepts Summary
• Source-Path-Receiver as a system1. Reduce Source
2. Rank and Manage Paths
3. Consider Subjective Response
• Effective Isolation
• Mode Management
• Nodal Point Placement
• Attachment Stiffness
• “Downstream” (Body Panel) Considerations
• Source-Path-Receiver as a system1. Reduce Source
2. Rank and Manage Paths
3. Consider Subjective Response
• Effective Isolation
• Mode Management
• Nodal Point Placement
• Attachment Stiffness
• “Downstream” (Body Panel) Considerations
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
SAE 2011 NVH ConferenceStructure Borne NVH Workshop
Thank You for Your Time!
Q & AQ & A
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Primary References (Workshop Basis: 4 Papers)
1. A. E. Duncan, et. al., “Understanding NVH Basics”, IBEC, 1996
2. A. E. Duncan, et. al., “MSC/NVH_Manager Helps Chrysler Make Quieter Vibration-free Vehicles”, Chrysler PR Article, March 1998.
3. B. Dong, et. al., “Process to Achieve NVH Goals: Subsystem Targets via ‘Digital Prototype’ Simulations”, SAE 1999-01-1692, NVH Conference Proceedings, May 1999.
4. S. D. Gogate, et. al., “’Digital Prototype’ Simulations to Achieve Vehicle Level NVH Targets in the Presence of Uncertainties’”,
SAE 2001-01-1529, NVH Conference Proceedings, May 2001
Structure Borne NVH References
WS + Refs. at www.AutoAnalytics.com/papers.html
Structure Borne NVH Workshop - on InternetAt SAE www.sae.org/events/nvc/specialevents.htm
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2011 SAE Structure Borne NVH Workshop www.autoanalytics.com
Supplemental Reference Recommendations
5. T.D. Gillespie, Fundamentals of Vehicle Dynamics, SAE 1992(Also see SAE Video Lectures Series, same topic and author)
6. D. E. Cole, Elementary Vehicle Dynamics, Dept. of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, Sept. 1972
7. J. Y. Wong, Theory of Ground Vehicles, John Wiley & Sons, New York, 1978
8. N. Takata, et.al. (1986), “An Analysis of Ride Harshness” Int. Journal of Vehicle Design, Special Issue on Vehicle Safety, pp. 291-303.
9. T. Ushijima, et.al. “Objective Harshness Evaluation” SAE Paper No. 951374, (1995).
Structure Borne NVH References