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NVH Workshop Presenters: A. E. Duncan Material Sciences Corp. G. Goetchius Material Sciences Corp. S. Gogate DaimlerChrysler Corp. Sponsored By: SAE Noise and Vibration Committee Structure Borne NVH Basics SAE 2007 NVH Conference; St. Charles, Illinois Wednesday Evening, May 16, 2007

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Page 1: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Presenters:

A. E. Duncan Material Sciences Corp.

G. Goetchius Material Sciences Corp.

S. Gogate DaimlerChrysler Corp.

Sponsored By:SAE Noise and Vibration Committee

Structure Borne NVH BasicsSAE 2007 NVH Conference; St. Charles, Illinois

Wednesday Evening, May 16, 2007

Page 2: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

NVH Workshop Topic Outline• Introduction• Fundamentals in NVH• Automotive NVH Load Conditions• Low Frequency Basics• Live Noise Attenuation Demo• Mid Frequency Basics• Utilization of Simulation Models• Closing Remarks

Page 3: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

The Fundamental Secret ofStructure Borne

NVH Performance

The Fundamental Secret ofStructure Borne

NVH Performance

Revealed here today !

Page 4: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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

Available online at www.AutoAnalytics.com

Structure Borne NVH Workshop - on Internet

Page 5: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Supplemental References5. 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. Kompella, M. S., and Bernhard, J., “Measurement of the Statistical Variation of Structural-Acoustic Characteristics of Automotive Vehicles”, SAE No. 931272, 1993

9. Freymann, R., and Stryczek, R., “A New Optimization Approach in the Field of Structural-Acoustics”, SAE No. 2000-01-0729, 2000

Structure Borne NVH References

Page 6: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

NVH Workshop Topic Outline• Introduction

• Fundamentals in NVH

• Automotive NVH Load Conditions

• Low Frequency Basics

Page 7: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Rideand

Handling

NVH Durability

ImpactCrashWorthiness

Competing Vehicle Design Disciplines

Page 8: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

NVH Workshop Topic Outline • Introduction

• Fundamentals in NVH

• NVH Load Conditions

• Low Frequency Basics

Page 9: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Fundamentals in NVH

• What is N, V and H?

• Time and Frequency Relation

• Subjective to Objective Conversions

• Single Degree of Vibration and Vibration Isolation Principle

• Automotive NVH Frequency Range

Page 10: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

What is N, V and H?(in Automotive Context)

Noise : Vibration perceived audibly and characterized as sensations of pressure by the ear

Together, they define the measure of vehicle NVH Quality

Based on SAEJ670e Standard (Vehicle Dynamics Committee July 1952)

Vibration : Perceived tactually (at vehicle occupant interface points of steering column, seats, etc.

Harshness : Related to transient nature of vibration and noise associated with abrupt transition in vehicle motion. It could be perceived both tactually and audibly

Page 11: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Time and Frequency Relation

TactileTactile

AcousticAcoustic

Operating loads Operating loadsOperating loads

TactileTactile

Time (Sec)

Tact

ile o

r Aco

ustic

Res

pons

e

• Responses perceived in vehicle vary with time as vehicle operates under loads

• Responses are usually steady state and periodic in nature

• It is convenient and intuitive to consider responses in frequency domain while preserving the signal content

Page 12: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Time and Frequency Relation• Conversion to frequency domain lends to formulation of principles for addressing structure borne NVH

Am

plitu

de

Time

Frequency (Hz)

5 Hz(Vehicle RigidBody Mode)

15 Hz(SuspensionMode)

25 Hz(Vehicle FlexibleBody Mode)

40 Hz(ColumnMode)

Overall Response, X(t)

Time (Sec)

Phas

ed S

umm

atio

n

X(f)

Page 13: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Time and Frequency Relation

X ( f ) = Fourier Transform of X ( t )

• Mathematically Speaking …….

Page 14: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Time and Frequency Relation• Responses can be obtained in frequency domain either through Fourier Transform of time domain signal or directly in frequency domain

Vehicle System Fourier Transform

X ( t ) X ( f )F ( t )

Test World

X ( f )

Common in Simulation World

Vehicle SystemF ( f )

Fourier Transform

Page 15: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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

31

8

2

6

4

7

5

NVH Model of Unibody Passenger CarSymbolic Outline

From Reference 6

Page 16: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Excitation Bump Profile

0.0

5.0

10.0

15.0

20.0

0 100 200 300 400 500

Distance (mm)

Pro

file

Hei

ght

(mm

) Profile

On to 100,380

Page 17: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Pitch at Mid-Car DOF3

-1.0E-04

-8.0E-05

-6.0E-05

-4.0E-05

-2.0E-05

0.0E+00

2.0E-05

4.0E-05

6.0E-05

8.0E-05

1.0E-04

0 1 2 3Time (sec.)

Ro

tati

on

- R

adia

ns Base Model

Page 18: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Pitch Response - Baseline Model

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

0.0 5.0 10.0 15.0 20.0Frequency Hz

Ro

tati

on

Rad

ian

s

Base Model

Page 19: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

FFT of the Input Bump

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

0.E+00 4.E-03 8.E-03 1.E-02 2.E-02 2.E-02

Cycles / mm

Ampl

itude

mm

Bump FFT

Transform Input Force to F(f)

20 Hz @ 45 MPH

0.0 20.0 Hz

Amplitude is Approximately Constant over the Frequency Range

Constant Displacement

Page 20: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

P itch at M id -C ar D O F 3

1 .0 E-0 8

1 .0 E-0 7

1 .0 E-0 6

1 .0 E-0 5

1 .0 E-0 4

0 5 1 0 1 5 2 0F req u en cy H z

Ro

tati

on

Rad

ian

s Tim e Dom ain F F T

F F T of Input

Page 21: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Subjective 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

Page 22: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

m

APPLIED FORCE

F = FO sin 2 π f t

k c FT

TR = FT / F

TransmittedForce

Single Degree of Freedom Vibration

=√ f 2fn

2) 2

ffn

( 2 d ) 21 +1 + ffn

( 2 d ) 21 +

( 1- ffn

( 2 d ) 2+

d = fraction of critical damping

fn = natural frequency √(k/m)

f = operating frequency

Page 23: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

0 1 2 3 4 50

1

2

3

4Tr

ansm

issi

bilit

y R

atio

1.414

0.5

0.1

0.15

0.375

1.0

0.25

Frequency 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

Page 24: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Excitation Force Comingfrom Engine F0

FT

Transmissibility Force Ratio is FT/F0

Isolation from an Applied Force

Support Forces Transmitted to Body

Example:A 4 Cyl. Excitation for Firing

Pulse at 700 RPM has a second order gas pressure torque at 23.3 Hz. Thus, to obtain isolation, the engine roll mode must be below 16.6 Hz.

Page 25: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Structure Borne NoiseAirborne Noise

Res

pons

e

Log Frequency

“Low”Global Stiffness

“Mid”

Local Stiffness+

Damping

“High”

Absorption+

Mass+

Sealing

~ 150 Hz ~ 1000 Hz ~ 10,000 Hz

Automotive NVH Frequency Range

Page 26: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

NVH Workshop Outline• Introduction

• Fundamentals in NVH

• NVH Load Conditions

• Low Frequency Basics

Page 27: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Two Main Sources

Noise and Vibration Sources

Suspension Powertrain

Page 28: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Typical NVH Pathways to the Passenger

PATHS FOR

STRUCTURE BORNE

NVH

Page 29: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Powertrain Induced

Page 30: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

NVH Workshop Topic Outline• Introduction

• Fundamentals in NVH

• NVH Load Conditions

• Low Frequency Basics

Page 31: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

RECEIVER

PATH

SOURCE

Low Frequency NVH Fundamentals

Page 32: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Vibration and Noise Attenuation Methods

Main Attenuation Strategies• Reduce the Input Forces from the Source

• Provide Isolation

• Mode Management

• Nodal Point Mounting

• Dynamic Absorbers

Page 33: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

8 Degree of Freedom Vehicle NVH Model

1 2 4 5

6 7

8

3

TiresWheels

SuspensionSprings

Engine Mass

EngineIsolator

Flexible Beam for Body

Page 34: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Vibration and Noise Attenuation Methods

Main Attenuation Strategies• Reduce the Input Forces from the Source

• Provide Isolation

• Mode Management

• Nodal Point Mounting

• Dynamic Absorbers

Page 35: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Reduction of Input Forces from the Source

Road Load Excitation• Use Bigger / Softer Tires• Reduce Tire Force Variation• Drive on Smoother Roads

Powertrain Excitation• Reduce Driveshaft Unbalance Tolerance• Use a Smaller Output Engine• Move Idle Speed to Avoid Excitation Alignment• Modify Reciprocating Imbalance to alter Amplitude or

Plane of Action of the Force.

Page 36: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Vibration and Noise Attenuation Methods

Main Attenuation Strategies• Reduce the Input Forces from the Source

• Provide Improved Isolation

• Mode Management

• Nodal Point Mounting

• Dynamic Absorbers

Page 37: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

8 Degree of Freedom Vehicle NVH ModelForce Applied to Powertrain Assembly

Forces at Powertrain could represent a First OrderRotating Imbalance

1 2 4 5

6 7

8

3

Feng

Page 38: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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

Page 39: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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

Page 40: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

8 Degree of Freedom Vehicle NVH ModelRemoved Double Isolation Effect

1 2 4 5

6 7

8

3

WheelMass

Removed

Page 41: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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

Page 42: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Vibration and Noise Attenuation Methods

Main Attenuation Strategies• Reduce the Input Forces from the Source

• Provide Isolation

• Mode Management

• Nodal Point Mounting

• Dynamic Absorbers

Page 43: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Mode Management

• Provide Separation between:

• Critical modes of Sub-systems in Vehicle (e.g. Body, Suspension, Powertrain, etc.)

• Critical modes of Sub-systems and Excitation

Page 44: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

1 2 4 5

6 7

8

3

Beam Stiffness which represents the body stiffness was adjusted to align Bending Frequency with Suspension Modes and then progressively separated back to Baseline.

Need for Mode Management

Baseline Bending 18.2 Hz

Baseline Suspension 10.6 Hz

TiresWheels

SuspensionSprings

Flexible Beam for Body

Page 45: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

8 DOF Mode Separation ExampleResponse 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

18.2 Hz13.0 Hz

10.6 HzProgressive reduction in the

“vehicle” bending mode

Suspension Mode

Page 46: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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)

Page 47: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Campbell Diagram

Frequency (Hz)

Engi

ne R

PM

1st Harmonic

2nd Harmonic

3rd Harmonic

Glo

bal B

ody

Tors

ion

Stee

ring

Col

umn

Vert

ical

30Hz 32Hz

600 RPM

• Campbell Diagram simultaneously represents excitations and vehicle system modes on a RPM vs. Frequency axis system

• A more convenient way (compared to mode management charts) of understanding the interaction among modes and excitation and mapping onto ERPM and vehicle speed

Page 48: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Vibration and Noise Attenuation Methods

Main Attenuation Strategies• Reduce the Input Forces from the Source

• Provide Isolation

• Mode Management

• Nodal Point Mounting

• Dynamic Absorbers

Page 49: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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.

Page 50: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Nodal Point Mounting ExamplesMount at Nodal Point

Transmission Mount of a3 Mount N-S P/T is nearthe Torsion Node.

Rear ViewEngine

1 2 4 5

6 7

3

Passenger sits at node point for First Torsion.

Mount system is placed to support Powertrain at the Nodal Locations of the First order Bending Mode.

Page 51: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

8 Degree of Freedom Vehicle NVH ModelBending Node Alignment with Wheel Centers

1 2 4 5

6 7

8

3

Redistribute Beam Masses to move Node Points to

Align with points 2 and 4

Page 52: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

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

Page 53: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

Vibration and Noise Attenuation Methods

Main Attenuation Strategies• Reduce the Input Forces from the Source

• Provide Isolation

• Mode Management

• Nodal Point Mounting

• Dynamic Absorbers

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0.0 0.5 1.0 1.5 2.0Frequency Hz

Dis

plac

emen

t m

m

YO

xSDOF

Dynamic Absorber Concept

MYO

x

Auxiliary Spring-Mass-Damperm = M / 10

2DOFM

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NVH Workshop

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]

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Baseline Sound Level63 Hz Dynamic Absorber63 + 110 Hz Absorbers

Baseline Sound Level63 Hz Dynamic Absorber63 + 110 Hz Absorbers

[Figure Courtesy of DaimlerChrysler Corporation]

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Vibration and Noise Attenuation MethodsMain Attenuation Strategies

• Reduce the Input Forces from the Source

• Provide Isolation

• Mode Management

• Nodal Point Mounting

• Dynamic AbsorbersThe above attenuation concepts have been demonstrated using simulation model results. A similar demonstration using physical hardware would have required more cost and time. Hardware testing in low frequency range could be used as a finalverification tool

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NVH Workshop Topic Outline• Introduction• Fundamentals in NVH• Automotive NVH Load Conditions• Low Frequency Basics• Live Noise Attenuation Demo• Mid Frequency Basics• Utilization of Simulation Models• Closing Remarks

Greg Goetchius

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NVH Workshop

NVH Workshop Topic Outline• Introduction• Fundamentals in NVH• Automotive NVH Load Conditions• Low Frequency Basics• Live Noise Attenuation Demo• Mid Frequency Basics• Utilization of Simulation Models• Closing Remarks

Alan Duncan

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RECEIVER

PATH

SOURCE

Mid Frequency NVH Fundamentals

This looks familiar!Frequency Range of Interest has changed to

150 Hz to 500 Hz

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Typical NVH Pathways to the Passenger

PATHS FOR

STRUCTURE BORNE

NVH

Noise Paths are thesame as Low

Frequency Region

Noise Paths are thesame as Low

Frequency Region

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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.

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Mid-Frequency Analysis Character

• Important characteristics of mid frequency analysis

&

Identifying Key Noise Paths

Effective Isolation

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Mid-Frequency Analysis Character

&

• Important characteristics of mid frequency analysis

Identifying Key Noise Paths

Effective IsolationEffective Isolation

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Classical SDOF: Rigid Source and Receiver

Tran

smis

sibi

li ty

Rat

i o

1.0 1.414 10.0

f / f n

“Real Structure”Flexible (Mobile)Source and Receiver

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

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Mobility• Mobility is the ratio of velocity response at the excitation point on structure

where point force is applied

Mobility =Velocity

Force

• Mobility, related to Admittance, characterizes Dynamic Stiffness of the structure at load application point

Mobility =Frequency * Displacement

Force

=Frequency

Dynamic Stiffness

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• The isolation effectiveness can be quantified by a theoretical model based on analysis of mobilities of receiver, isolator and source

• Transmissibility ratio 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 r

F 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

2003, 2005 ERRATA

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• The isolation effectiveness can be quantified by a theoretical model based on analysis of mobilities of receiver, isolator and source

• Transmissibility ratio 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 r

F 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

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Isolation

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 m

F im

Receiver

Source

F if

F f V f

Isolator

TR = Force from source without an isolator Force from source with an isolator

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Mid-Frequency Analysis Character

Effective Isolation

&

• Important characteristics of mid frequency analysis

Identifying Key Noise PathsIdentifying Key Noise Paths

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Identifying Key NVH PathsKey NVH paths are identified by Transfer Path Analysis (TPA)

Fi

TactileTransferTactile

TransferAcousticTransfer

AcousticTransfer

Operating loads Operating loads

• TPA is a technique to perform phased summation of partial responses through all NVH paths to give total tactile or acoustic response under operating loads at a given frequency

• TPA is applicable in both testing and simulation scenarios to identify key paths

Break the system at the points where the forces enter the body (Receiver)

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NVH Workshop

Noise Path Analysis

Fi

• Total Acoustic Response is summation of partial responses over all noise paths

Pt = Σ paths [Pi ] = Σ paths [ (P/F) i * Fi ]

Acoustic Transfer (P/F)iAcoustic Transfer (P/F)i

Pi : Partial contribution of path i due to operating force

Operating loads createForces (Fi) into body atAll noise paths

(P/F) i : Acoustic Transfer Function of the ith Path

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NVH Workshop

Transfer Path Analysis

( contributors + )

( reducers - )

FrontUpperControlArm

FrontShockAbsorber Rear

ShockAbsorber

RearUpperArm

TotalNoise

( AllPaths)

FrontStabilizer

FrontSpring

• TPA allows path rankings based on contribution to total response of noise paths at a given frequency

• TPA thus helps identify key noise paths

• TPA is mainly used for acoustic response in mid frequency range

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Designing for Mid Frequency

• Important characteristics of mid frequency analysis

Effective Isolation

&

Identifying Key Noise Paths

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Designing for Mid Frequency

When designing a new vehicle, the first phase is to satisfy generic targets for key parameters along all noise paths in order to achieve effective isolation.

What are these generic targets andkey parameters ?

What are these generic targets andkey parameters ?

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Generic Noise Path Targets

Operating loads Operating loads

Acoustic Transfer (P/F)iAcoustic Transfer (P/F)i

Δ XKBsng

V/F

P/VP/F

F

Ksource

(Kbody)

Transmissibility along a given noise path (TRi)

TR = ⏐ ( Y r + Y s ) / ( Y i + Y r + Y s ) ⏐

TR = ⏐ ( ) / ( ) ⏐K body

1K source

1+ K body

1 + K iso.

1K source

1+

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Generic Noise Path TargetsTR = ⏐ ( ) / ( ) ⏐K body

1K source

1+ K body

1 + K iso.

1K source

1+

K iso

K sourceK body

K iso1.0 5.0 Infinite

1.0

5.0

Infinite

0.67 0.54 0.50

0.54 0.28 0.17

0.50 0.17 0.00

As a generic target, body to bushing stiffness ratio of at least 5.0 and very high source to bushing stiffness ratio (~ infinite) is desired to achieve “good” TR of 0.17

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0

0.1

0.2

0.3

0.4

0.5

1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10

Series2

0.0

0.1

0.2

0.3

0.4

0.5

1 2 3 4 5 6 7 8 9 10

Stiffness Ratio; K body / K bsg

Tran

smis

sibi

lity

Rat

io

TR = ⏐ ( K bsg ) / ( K bsg + K body ) ⏐For an infinite source

Target Min. = 5 gives TR = .17

Relationship of Body-to-Bushing Stiffness Ratio to Transmissibility

K body.

K bsg

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Fi

Operating loads Operating loads

Acoustic Transfer (P/F)iAcoustic Transfer (P/F)i

Operating loads createForces (Fi) into body atAll noise paths

Pt = Σ paths [Pi ] = Σ paths [ Fi * (P/F) i ] = Σ paths [ Fi * (P/V) i * (V/F)i]

Generic Noise Path Targets

(P/F) Acoustic Sensitivity(V/F) Structural Point Mobility (Receiver)

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Generic Noise Path Targets

• For a given force generated at a source attachment to body, lowering sensitivities (P/F) or (V/F) along a pathwould reduce total response

• Typical generic targets,

- Acoustic Sensitivity (P/F) in 50 - 60 dBL/N range

- Structural Mobility (V/F) less than 0.2 - 0.3 mm/sec/N

For example, for Acoustic Response Pt

Pt = Σ paths [Pi ] = Σ paths [ Fi * (P/F) i ] = Σ paths [ Fi * (P/V) i * (V/F)i]

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Generic Noise Path Targets

K iso

K body >= 5.0K iso

K source ~ infinite

AcousticSensitivity < 50 - 60

dBL/N

StructuralMobility < .2 to .3 mm/sec/N

How does one achieve these generic targets ?

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Generic Noise Path TargetsHow does one achieve

• Increase local body attachment stiffness (Kbody) through structural modifications

K iso

K body >= 5.0

• Reduce attachment isolator stiffness (Kiso) while balancing the conflicting requirement of other functionalities such as Ride & Handling

StructuralMobility < .2 - .3

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How does one achieve

• Increase source side attachment stiffness (Ksource)

• Reduce attachment isolator stiffness (Kiso)

K iso

K source ~ infinite

In Automotive Structures, it is realistic to expect that the Source to isolator stiffness ratio is high since Source usually corresponds to a stiff structure (such as powertrain or axle).

Generic Noise Path Targets

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How does one achieve

• At a given frequency, Acoustic Sensitivity (P/F) is

P/F = (P/V) X FrequencyBody stiffness

• Based on the above equation, increasing body stiffness usually reduces Acoustic Sensitivity.

Generic Noise Path Targets

AcousticSensitivity < 50 - 60

dBL/N

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NVH Workshop

How does one achieve:

• In such cases, the Acoustic Sensitivity can be reduced by reducing the overall body panel velocity through application of damping treatments

• There are situations when increasing body stiffness does not reduce Acoustic Sensitivity

AcousticSensitivity < 50 - 60

dBL/N

Generic Noise Path Targets

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Application of Damping TreatmentEffect on sound response of damping treatment

applied on key identified contributing panels

[Figure Courtesy of DaimlerChrysler Corporation]

12.5dBA Reduction

Floor without damping treatment

Floor with damping treatment

Frequency (Hz)

5.0 dBA

SPL

(dB

A)

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Designing for Mid Frequency

While designing a new vehicle, generic targets are set for key parameters along all noise paths in order to achieve effective isolation.

Is it really necessary to achieve generic targets forall noise paths ?

Is it really necessary to achieve generic targets forall noise paths ?

Probably Not !!Probably Not !!

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Designing for Mid FrequencyDriver’s Ear Noise

Vehicle Level Response

Original Noise Path Contributions

Transfer Path Analysis

Some noise paths are more dominant than others

Impose more strict requirements for these dominant paths and relax requirements for other paths to achieve more “rebalanced”noise

Improved Noise Path Contributions

Driver’s Ear Noise

Vehicle Response to Meet NVH Targets

Original NoiseReduced Noise

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Yesor

Time Out

No

Re-DesignSub-System

Evaluate Sub-SystemPerformance

Evaluate Sub-SystemPerformance

No

Meet VehicleGoals?

RebalanceTrade-OffRebalanceTrade-Off

Meet Sub-System

Goals? Evaluate Vehicle GoalsEvaluate Vehicle Goals

Mid Frequency NVH Goal Achievement Process

Initial Sub-System Targets

Yesor

Time Out

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Designing for Mid Frequency

Principles to follow

• At the beginning of program, work towards generic targets for all noise paths in order to achieve effective isolation.

• As the design is firmed out, shift focus to key contributing noise paths using Transfer Path Analysis in order to meet target for all NVH operating load conditions.

• Perform path “rebalancing” to arrive at revised path targets if Sub-System goal achievement is not possible due to architectural constraints.

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Mid Frequency NVH Improvement (Sports Utility Vehicle Example)

Full Vehicle ModelFull Vehicle Model

[Figure Courtesy of DaimlerChrysler Corporation]

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Mid Frequency NVH Improvement(Sports Utility Vehicle Example)

Powertrain/Axle/Suspension ModelPowertrain/Axle/Suspension Model[Figure Courtesy of DaimlerChrysler Corporation]

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Mid Frequency NVH Improvement(Sports Utility Vehicle Example)

Acoustic Cavity ModelAcoustic Cavity Model[Figure Courtesy of DaimlerChrysler Corporation]

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Mid-Frequency NVH improvementAxle Whine Example : 300-500 Hz

θθ

θθ

Trimmed Body

Interior Acoustic Cavity

Chassis

Front and Rear Axle Gear-Pinion Mesh Transmission Error

SOURCE ------------- PATH ---------------- RECEIVER[Figure Courtesy of DaimlerChrysler Corporation]

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Axle Whine Example• Design work was focused in the beginning towards achievinggeneric targets for all noise paths

• As the design was firmed out, full vehicle analysis revealed under target performance for Driver’s ear SPL response which was dominated by rear excitation

[Figure Courtesy of DaimlerChrysler Corporation]

400 Hz 500 Hz300 Hz

10dBA

FR + RR Excitation

FR Excitation Only

RR Excitation Only(Dominates Total Content)

Target Level

Sound Response with Varying Excitation

Frequency (Hz)

SPL(

dBA

)

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Axle Whine Example• Before embarking on identifying the root cause for under-target performance at dominant noise paths, it is a good practice to perform a reasonableness check on the response.• Steps for Reasonableness Determination:

Judging the response based on System Knowledge• Total response content is dominated by rear excitation. This is

reasonable since vehicle has IFS and solid axle rear suspension which is harder to isolate for noise

Forced Mode Animation • Operating deformed shape motion is rear axle pitching about ring

gear axis. This was expected since input excitation is MTE imposed as enforced angular rotation between ring and pinion gear

Disconnect Studies• Disconnecting rear suspension noise paths (shock in particular) had

the most significant effect on Driver’s SPL response

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Axle Whine Example• Transfer Path Analysis

• Dominant Paths• Rear left shock vertical• Rear LCA vertical : Left is positive whereas right is negative contributor • Rear Right shock vertical

• The conclusion matches with reasonableness checks[Figure Courtesy of DaimlerChrysler Corporation]

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Pt = Σ paths [Pi ] = Σ paths [ Fi * (P/F) i ]

• Is it high forces or high acoustic sensitivity at shock to body attachment ?

Acoustic sensitivity was better than generic targetAcoustic sensitivity was better than generic target

Axle Whine Example

• The issue is with high forces into the body through shock attachment due to stiff shock bushings

• Stiff shock bushings gave low body-to-bushing stiffness ratio

[Figure Courtesy of DaimlerChrysler Corporation]

5dBL/N

Aco

ustic

Sen

sitiv

ity (d

BL/

N)

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Axle Whine ExampleSolution• Soften shock vertical bushings by 65%

• To balance this against Ride and Handling requirement of stiff bushing, local attachment stiffness between shock and body was improved through a new bracket design

• This addition of bracket improved right shock mobility 3 times

whereasleft shock mobility by 1.5 times thereby improving isolation effectiveness of shock bushing

[Figure Courtesy of DaimlerChrysler Corporation]

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Axle Whine ExampleResponse Improvement due to proposed solution

[Figure Courtesy of DaimlerChrysler Corporation]

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Axle Whine ExampleHow Robust is the proposed solution ?• Parameter variations such as weld deletion in “new bracket” and gage changes were considered to study robustness of solution

10 dBA

Deterministic Responseof Model with proposal

Scatter of modelWith proposals

Baseline ModelScatter

Vehicle Speed (mph)49.5 50.7 51.9 53.2 54.4

Driv

er’s

Ear

SPL

(dB

A)

48.2

Deterministic Responseof Baseline Model

- Response scatter of modelwith proposal does notoverlap baseline model response scatter indicatinga robust solution

- The problem peak has nowshifted to a new vehiclespeed of 50.7 mph whichrequires a new contributionanalysis

[Figure Courtesy of DaimlerChrysler Corporation]

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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

• It is important to balance NVH requirements againstother functionalities (Ride and Handling, Impact)

• It is important to balance NVH requirements againstother functionalities (Ride and Handling, Impact)

• It is important to understand the robustness ofdesign recommendations

• It is important to understand the robustness ofdesign recommendations

• Other means of dealing high levels of source input(Tuned dampers, damping treatments, isolatorplacement at nodal locations) are also effective

• Other means of dealing high levels of source input(Tuned dampers, damping treatments, isolatorplacement at nodal locations) are also effective

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NVH Workshop

NVH Workshop Topic Outline• Introduction• Fundamentals in NVH• Automotive NVH Load Conditions• Low Frequency Basics• Live Noise Attenuation Demo• Mid Frequency Basics• Utilization of Simulation Models• Closing Remarks

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NVH Workshop

Utilizing NVH Simulation Models

Considerations• Some Agreement: Math Models can be used as Trend Predictors.

(but not for absolute levels, yet.)

• Q. How do I make design decisions before hardware is available?• ANS. Correlation must be performed on existing hardware to

establish modeling methods and correlation criteria to be applied to the future design.

(The Reference Baseline Ref. 3) A model of the new design is built with the same Methodology as the Reference Baseline to predict the change in performance as the design process progresses but before prototypes are available.

• Q. How do I know my model is good?• ANS. We require correlation work to know the simulation compares

to test values to some degree.

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NVH Workshop

Utilizing NVH Simulation Models

Considerations• Q. How do I compare my model to test measurement and how close

does it have to be to assure it can be used as a trend predictor?• ANS. If model predictions were within the band of variability of the

test measurement, for a statistically significant number of samples, this would increase confidence in the predictive capability.

• Q. How wide is the band of variability?• ANS. Let’s EXPLORE it !!!!

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NVH Workshop

Discussion of Product Variability

Topics

• Kompella and Bernhard Observations

• Freyman NVH Scatter Results

• Model Confidence Criteria

• Conclusions

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NVH Workshop

Frequency ( Hz )

Mag

. of F

RF

Magnitude of 99 Structure – borne FRF’s for theRodeo’s for the driver microphone( Ref. 8 ) ©1993 Society of Automotive Engineers, Inc.

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NVH Workshop( Ref. 9 ) ©2000 Society of Automotive Engineers, Inc.

Frequency ( Hz )

Soun

d Pr

essu

re [

dB( l

in)]

Frequency ( Hz )

Phas

e [o ]

Acoustic scatter numerically determined in the vibro – acoustic behavior of a vehicle due to possible tolerances in the component area and in the production process

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NVH Workshop

Reference Baseline Confidence CriterionFor Operating Response Simulations

Test Upper BoundTest Band AverageTest Lower Bound

Test Variation Band10. dB; 50-150 Hz20. dB; 150-500 Hz

REF. 8

Confidence Criterion:Simulation result mustfall within the band oftest variation.

Simulation Prediction

FUDGEFACTORS

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NVH Workshop

Axle Whine Example• Design work was focused in the beginning towards achieving generic targets for all noise paths

• As the design was firmed out, full vehicle analysis revealed under target performance for Driver’s ear SPL response which was dominated by rear excitation

[Figure Courtesy of DaimlerChrysler Corporation]

400 Hz 500 Hz300 Hz

10dBA

FR + RR Excitation

FR Excitation Only

RR Excitation Only(Dominates Total Content)

Target Level

Sound Response with Varying Excitation

Frequency (Hz)

SPL(

dBA

)

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NVH Workshop

Conclusions:Significant Product Variation exists even in best-in-class vehicles.

Correlation should be considered as being within the band of variability whether test or simulation.

The Confidence Criteria, for operating responses, is a relatively challenging condition to meet when considering the following:

It uses the same bandwidth as Kompella (Ref. 8), determined from simple FRF’s, while the criteria is for operating responses which are subject to additional variation in the operating loads.It assumes that one test will generate the mean response level in the band subject to the condition that a “qualified” median performer will be tested. This requires a test engineer extremely experienced with the vehicle line in order to “qualify” the vehicle.

Best hope for reduced product development times is a coordinated effort of Virtual Vehicle Simulation and Reference Baseline and Physical Prototype Testing to grasp the complexities of NVH responses and the robustness of their sensitivity to variation.

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NVH Workshop

Rideand

Handling

NVH Durability

ImpactCrashWorthiness

Competing Vehicle Design Disciplines

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NVH Workshop

The Fundamental Secret ofStructure Borne

NVH Performance

The Fundamental Secret ofStructure Borne

NVH Performance

Revealed here today !

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NVH Workshop

The Fundamental Secret of Structure Borne NVH Performance

The Fundamental Secret of Structure The Fundamental Secret of Structure Borne NVH PerformanceBorne NVH Performance

Meets Conditions of the Attenuations Strategies

• Minimize the Source Load• Manage Mode Placement• Provide Isolation• Mount at Nodal Points• Provide Dynamic Absorber•Reduce Source - Receiver Mobility

To Minimize Structure Borne NVH, connect between Source and Receiver Sub-Systems at Locations where the Motion is at a Minimum.

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NVH Workshop

The Fundamental Secret of Structure Borne NVH Performance

The Fundamental Secret of Structure The Fundamental Secret of Structure Borne NVH PerformanceBorne NVH Performance

To Minimize Structure Borne NVH, connect between Source and Receiver Sub-Systems at Locations where the Motion is at a Minimum.

First Best Principle for NVH Improvement is Minimization /

Understanding of the Source Excitation.

Ist Corollary

Effectively Isolate the remaining source from the receivers at Key paths

2nd Corollary

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NVH Workshop

The Fundamental Secret of Structure Borne NVH Performance

The Fundamental Secret of Structure The Fundamental Secret of Structure Borne NVH PerformanceBorne NVH Performance

Meets Conditions of the Attenuations Strategies

• Minimize the Source Load• Manage Mode Placement• Provide Isolation• Mount at Nodal Points• Provide Dynamic Absorber•Reduce Source - Receiver Mobility

That’s All Folks !Thank You for Attending the

2007 Structure Borne NVH Workshop

Your Presenters today were:

Alan Duncan, Material Sciences Corp.

Greg Goetchius, Material Sciences Corp.

Sachin Gogate, DaimlerChrysler Corp.Visit: www.AutoAnalytics.com/papers.html (or www.sae.org)

to download the 2007 Structure Borne NVH Workshop

To Minimize Structure Borne NVH, connect between Source and Receiver Sub-Systems at Locations where the Motion is at a Minimum.

Page 117: Structure Borne NVH Basics - Automotive Analyticsautoanalytics.com/downloads/2007_NVH_str_borne_workshop_aai.pdf · NVH Workshop What is N, V and H? (in Automotive Context) N oise:

NVH Workshop

The Fundamental Secret of Structure Borne NVH Performance

The Fundamental Secret of Structure The Fundamental Secret of Structure Borne NVH PerformanceBorne NVH Performance

Meets Conditions of the Attenuations Strategies

• Minimize the Source Load• Manage Mode Placement• Provide Isolation• Mount at Nodal Points• Provide Dynamic Absorber•Reduce Source - Receiver Mobility

That’s All Folks !Thank You for Attending the

2007 Structure Borne NVH Workshop

Your Presenters today were:

Alan Duncan, Material Sciences Corp.

Greg Goetchius, Material Sciences Corp.

Sachin Gogate, DaimlerChrysler Corp.Visit: www.AutoAnalytics.com/papers.html (or www.sae.org)

to download the 2007 Structure Borne NVH Workshop

To Minimize Structure Borne NVH, connect between Source and Receiver Sub-Systems at Locations where the Motion is at a Minimum.