Noise and Vibration Control in Automotive Bodies

A comprehensive and versatile treatment of an important and complex topic in vehicle design

Written by an expert in the field with over 30 years of NVH experience, Noise and Vibration Control of Automotive Body offers nine informative chapters on all of the core knowledge required for noise, vibration, and harshness engineers to do their job properly. It starts with an introduction to noise and vibration problems; transfer of structural-borne noise and airborne noise to interior body; key techniques for body noise and vibration control; and noise and vibration control during vehicle development. The book then goes on to cover all the noise and vibration issues relating to the automotive body, including: overall body structure; local body structure; sound package; excitations exerted on the body and transfer functions; wind noise; body sound quality; body squeak and rattle; and the vehicle development process for an automotive body.

Vehicle noise and vibration is one of the most important attributes for modern vehicles, and it is extremely important to understand and solve NVH problems. Noise and Vibration Control of Automotive Body offers comprehensive coverage of automotive body noise and vibration analysis and control, making it an excellent guide for body design engineers and testing engineers.

• Covers all the noise and vibration issues relating to the automotive body
• Features a thorough set of tables, illustrations, photographs, and examples
• Introduces automotive body structure and noise and vibration problems
• Pulls together the diverse topics of body structure, sound package, sound quality, squeak and rattle, and target setting

Noise and Vibration Control of Automotive Body is a valuable reference for engineers, designers, researchers, and graduate students in the fields of automotive body design and NVH.

Jian Pang, PhD, is a lecturer for the Society of Automotive Engineers in both the United States and China. He has worked at both the Ford Motor Company in Detroit, US and the Changan Automobile Company of Chongqing, China. He has a strong theoretical background on noise and vibration and has worked on vehicle development for automotive companies for many years.

Preface xiii

1 Introduction 1

1.1 Automotive Body Structure and Noise and Vibration Problems 1

1.1.1 Automotive Body Structure 1

1.1.2 Noise and Vibration Problems Caused by Body Frame Structure 7

1.1.3 Noise and Vibration Problems Caused by Body Panel Structure 8

1.1.4 Interior Trimmed Structure and Sound Treatment 8

1.1.5 Noise and Vibration Problems Caused by Body Accessory Structures 9

1.2 Transfer of Structural‐Borne Noise and Airborne Noise to Interior 10

1.2.1 Description of Vehicle Noise and Vibration Sources 10

1.2.2 Structural‐Borne Noise and Airborne Noise 11

1.2.3 Transfer of Noise and Vibration Sources to Interior 13

1.3 Key Techniques for Body Noise and Vibration Control 14

1.3.1 Vibration and Control of Overall Body Structure 15

1.3.2 Vibration and Sound Radiation of Body Local Structures 17

1.3.3 Sound Package for Vehicle Body 24

1.3.4 Body Noise and Vibration Sensitivity 28

1.3.5 Wind Noise and Control 32

1.3.6 Door Closing Sound Quality and Control 35

1.3.7 Squeak and Rattle of Vehicle Body 38

1.4 Noise and Vibration Control During Vehicle Development 39

1.4.1 Modal Frequency Distribution for Vehicle Body 40

1.4.2 Body NVH Target System 41

1.4.3 Execution of Body NVH Targets 42

1.5 Structure of This Book 42

2 Vibration Control of Overall Body Structure 45

2.1 Introduction 45

2.1.1 Overall Body Stiffness 45

2.1.2 Overall Body Modes 48

2.1.3 Scopes of Overall Body Vibration Research 50

2.2 Overall Body Stiffness 51

2.2.1 Body Bending Stiffness 52

2.2.2 Body Torsional Stiffness 57

2.3 Control of Overall Body Stiffness 61

2.3.1 Overall Layout of a Body Structure 62

2.3.2 Body Frame Cross‐Section and Stiffness Analysis 65

2.3.3 Joint Stiffness 67

2.3.4 Influence of Adhesive Bonding Stiffness on Overall Body Stiffness 71

2.3.5 Contribution Analysis of Beams and Joints on Overall Body Stiffness 72

2.4 Identification of Overall Body Modes 75

2.4.1 Foundation of Modal Analysis 75

2.4.2 Modal Shape and Frequency of Vehicle Body 78

2.4.3 Modal Testing for Vehicle Body 84

2.4.4 Calculation of Vehicle Body Mode 89

2.5 Control of Overall Body Modes 91

2.5.1 Separation and Decoupling of Body Modes 91

2.5.2 Planning Table/Chart of Body Modes 93

2.5.3 Control of Overall Body Modes 98

Bibliography 101

3 Noise and Vibration Control for Local Body Structures 103

3.1 Noise and Vibration Problems Caused by Vehicle Local Structures 103

3.1.1 Classification and Modes of Local Body Structures 103

3.1.2 Noise and Vibration Problems Generated by Local Modes 104

3.1.3 Control Strategy for Local Modes 111

3.2 Body Plate Vibration and Sound Radiation 112

3.2.1 Vibration of Plate Structure 113

3.2.2 Sound Radiation of Plate Structure 116

3.3 Body Acoustic Cavity Mode 120

3.3.1 Definition and Shapes of Acoustic Cavity Mode 120

3.3.2 Theoretical Analysis and Measurement of Acoustic Cavity Mode 122

3.3.3 Coupling of Acoustic Cavity Mode and Structural Mode 129

3.3.4 Control of Acoustic Cavity Mode 130

3.4 Panel Contribution Analysis 131

3.4.1 Concept of Panel Contribution 131

3.4.2 Contribution Analysis of Panel Vibration and Sound Radiation 132

3.4.3 Testing Methods for Panel Vibration and Sound Radiation 136

3.5 Damping Control for Structural Vibration and Sound Radiation 145

3.5.1 Damping Phenomenon and Description 145

3.5.2 Damping Models 146

3.5.3 Loss Factor 149

3.5.4 Characteristics of Viscoelastic Damping Materials 150

3.5.5 Classification of Body Damping Materials and Damping Structures 153

3.5.6 Measurement of Damping Loss Factor 157

3.5.7 Application of Damping Materials and Structures on Vehicle Body 159

3.6 Stiffness Control for Body Panel Vibration and Sound Radiation 162

3.6.1 Mechanism of Stiffness Control 164

3.6.2 Tuning of Plate Stiffness 166

3.6.3 Influence of Plate Stiffness Tuning on Sound Radiation 170

3.6.4 Case Study of Body Stiffness Tuning 170

3.7 Mass Control for Body Panel Vibration and Sound Radiation 175

3.7.1 Mechanism of Mass Control 175

3.7.2 Application of Mass Control 175

3.8 Damper Control for Body Vibration and Sound Radiation 179

3.8.1 Mechanism of Dynamic Damper 179

3.8.2 Application of Dynamic Damper to Attenuate Interior Booming 181

3.9 Noise and Vibration for Body Accessory Components 182

3.9.1 Bracket Mode and Control 182

3.9.2 Control of Steering System Vibration 185

3.9.3 Control of Seat Vibration 190

Bibliography 195

4 Sound Package 201

4.1 Introduction 201

4.1.1 Transfer of Airborne‐Noise to Passenger Compartment 201

4.1.2 Scopes of Sound Package Research 202

4.2 Body Sealing 203

4.2.1 Importance of Sealing 203

4.2.2 Static Sealing and Dynamic Sealing 207

4.2.3 Measurement of Static Sealing 207

4.2.4 Control of Static Sealing 210

4.3 Sound Absorptive Materials 216

4.3.1 Sound Absorption Mechanism and Sound Absorption Coefficient 216

4.3.2 Porous Sound Absorptive Material 217

4.3.3 Resonant Sound Absorption Structure 222

4.3.4 Measurement of Sound Absorption Coefficient 224

4.4 Sound Insulation Materials and Structures 229

4.4.1 Mechanism of Sound Insulation and Sound Transmission Loss 229

4.4.2 Sound Insulation of Single Plate 230

4.4.3 Sound Insulation of Double Plate 233

4.4.4 Measurement of Sound Insulation Materials 236

4.5 Application of Sound Package 240

4.5.1 Application of Sound Absorptive Materials and Structures 241

4.5.2 Application of Combination of Sound Insulation Structures and Sound Absorptive Materials 247

4.5.3 Application of Sound Baffle Material 252

4.6 Statistical Energy Analysis and Its Application 254

4.6.1 Concepts of Statistical Energy Analysis 255

4.6.2 Theory of Statistical Energy Analysis 256

4.6.3 Assumptions and Applications of Statistical Energy Analysis 258

4.6.4 Loss Factor 260

4.6.5 Input Power 263

4.6.6 Application of Statistical Energy Analysis on Vehicle Body 264

Bibliography 267

5 Vehicle Body Sensitivity Analysis and Control 273

5.1 Introduction 273

5.1.1 System and Transfer Function 273

5.1.2 Vibration and Sound Excitation Points on Vehicle Body 275

5.1.3 Response Points 278

5.1.4 Body Sensitivity 278

5.2 Source– Transfer Path–Response Model for Vehicle Body 280

5.2.1 Source–Transfer Path–Response Model 280

5.2.2 Source–Transfer Function–Vibration Model for Vehicle Body 280

5.2.3 Source−Transfer Function−Noise Model for Vehicle Body 281

5.3 Characteristics and Analysis of Noise and Vibration Sources 284

5.3.1 Excitation Characteristics of Engine and Related Systems 284

5.3.2 Excitation Characteristics of Drivetrain System 286

5.3.3 Excitation Characteristics of Tires 291

5.3.4 Excitation Characteristics of Rotary Machines 293

5.3.5 Excitation Characteristics of Random or Impulse Inputs 294

5.4 Dynamic Stiffness and Input Point Inertance 295

5.4.1 Mechanical Impedance and Mobility 295

5.4.2 Driving Point Dynamic Stiffness 296

5.4.3 IPI and Driving Point Dynamic Stiffness 298

5.4.4 Control of Driving Point Dynamic Stiffness 301

5.5 Vibration− Vibration Sensitivity and Sound−Vibration Sensitivity 304

5.5.1 Transfer Processing of Vibration Sources to Interior Vibration and Vibration−Vibration Sensitivity 304

5.5.2 Transfer Processing of Vibration Sources to Interior Noise and Sound−Vibration Sensitivity 308

5.5.3 Sensitivity Control 311

5.5.4 Sensitivity Targets 315

5.6 Sound− Sound Sensitivity and Control 316

5.6.1 Sound Transmission from Outside Body to Interior 316

5.6.2 Expression of Sound−Sound Sensitivity 317

5.6.3 Targets and Control of Sound−Sound Sensitivity 322

Bibliography 323

6 Wind Noise 327

6.1 Introduction 327

6.1.1 Problems Induced by Wind Noise 327

6.1.2 Sound Sources and Classification of Wind Noise 328

6.2 Mechanism of Wind Noise 331

6.2.1 Pulsating Noise 331

6.2.2 Aspiration Noise 333

6.2.3 Buffeting Noise 336

6.2.4 Cavity Noise 338

6.3 Control Strategy for Wind Noise 339

6.3.1 Transfer Paths of Wind Noise 339

6.3.2 Control Strategy of Wind Noise 341

6.4 Body Overall Styling and Wind Noise Control 343

6.4.1 Ideal Body Overall Styling 343

6.4.2 Design of Transition Region between Front Grill and Engine Hook 345

6.4.3 Design in Area between Engine Hood and Front Windshield 346

6.4.4 Design of A‐Pillar Area 347

6.4.5 Design of Transition Area of Roof, Rear Windshield, and Trunk Lid 352

6.4.6 Underbody Design 353

6.4.7 Design in an Area of Wheelhouse and Body Side Panel 354

6.5 Body Local Design and Wind Noise Control 354

6.5.1 Principles for Body Local Structure Design 354

6.5.2 Design of Side Mirror and Its Connection with Body 355

6.5.3 Sunroof Design and Wind Noise Control 359

6.5.4 Antenna Design and Wind Noise Control 361

6.5.5 Design of Roof Luggage Rack 363

6.5.6 Control of Other Appendages and Outside Cavity 364

6.6 Dynamic Sealing and Control 365

6.6.1 Dynamic Sealing and Its Importance 365

6.6.2 Expression for Dynamic Sealing 366

6.6.3 Dynamic Sealing between Door and Body 368

6.6.4 Control of Dynamic Sealing 371

6.7 Measurement and Evaluation of Wind Noise 373

6.7.1 Wind Noise Testing in Wind Tunnel 373

6.7.2 Wind Noise Testing on Road 378

6.7.3 Evaluation of Wind Noise 379

6.8 Analysis of Wind Noise 380

6.8.1 Relationship Between Aerodynamic Acoustics and Classical Acoustics 380

6.8.2 Lighthill Acoustic Analogy Theory 381

6.8.3 Lighthill‐Curl Acoustic Analogy Theory 382

6.8.4 Solution of Aerodynamic Equations 383

6.8.5 Simulation of Wind Noise 383

Bibliography 384

7 Door Closing Sound Quality 389

7.1 Vehicle Sound Quality 389

7.1.1 Concept of Sound Quality 389

7.1.2 Automotive Sound Quality 390

7.1.3 Importance of Automotive Sound Quality 391

7.1.4 Scope of Sound Quality 392

7.2 Evaluation Indexes of Sound Quality 393

7.2.1 Description of Psychoacoustics 393

7.2.2 Evaluation Indexes of Psychoacoustics 395

7.2.3 Critical Band 397

7.2.4 Loudness 398

7.2.5 Sharpness 402

7.2.6 Modulation, Fluctuation, and Roughness 404

7.2.7 Tonality 409

7.2.8 Articulation Index 409

7.2.9 Sound Masking 411

7.3 Evaluation Indexes of Automotive Sound Quality 413

7.3.1 Classification of Automotive Sound Quality 413

7.3.2 Indexes Used to Describe Automotive Sound Quality 415

7.3.3 Indexes Used to Describe System Sound Quality 416

7.4 Evaluation of Door Closing Sound Quality 417

7.4.1 Importance of Door Closing Sound Quality 417

7.4.2 Subjective Evaluation of Door Closing Sound Quality 417

7.4.3 Objective Evaluation of Door Closing Sound Quality 419

7.4.4 Relation between Subjective Evaluation and Objective Evaluation 423

7.5 Structure and Noise Source of Door Closing System 424

7.5.1 Structure of Door Closing System 424

7.5.2 Noise Sources of Door Closing 426

7.6 Control of Door Closing Sound Quality 428

7.6.1 Control of Door Panel Structure 428

7.6.2 Control of Door Lock 430

7.6.3 Control of Sealing System 432

7.7 Design Procedure and Example Analysis for Door Closing Sound Quality 432

7.7.1 Design Procedure for Door Closing Sound Quality 432

7.7.2 Analysis of Factors Influencing on Loudness, Sharpness, and Ring‐Down 434

7.7.3 Example Analysis of Door Closing Sound Quality 435

7.8 Sound Quality for Other Body Components 437

Bibliography 438

8 Squeak and Rattle Control in Vehicle Body 441

8.1 Introduction 441

8.1.1 What Is Squeak and Rattle? 441

8.1.2 Components Generating Squeak and Rattle 442

8.1.3 Importance of Squeak and Rattle 442

8.1.4 Mechanism of Squeak and Rattle 442

8.1.5 Identification and Control of Squeak and Rattle 443

8.2 Mechanism and Influence Factors of Squeak 444

8.2.1 Mechanism of Squeak 444

8.2.2 Factors Influencing Squeak 447

8.3 Mechanism and Influence Factors of Rattle 449

8.3.1 Mechanism of Rattle 449

8.3.2 Factors Influencing Rattle 450

8.4 CAE Analysis of Squeak and Rattle 452

8.4.1 Analysis of Stiffness, Mode, and Deformation of Body and Door 453

8.4.2 Modal Analysis of Body Subsystems 455

8.4.3 Sensitivity Analysis of Squeak and Rattle 458

8.4.4 Dynamic Response Analysis of Squeak and Rattle 460

8.5 Subjective Evaluation and Testing of Squeak and Rattle 461

8.5.1 Subjective Identification and Evaluation of Squeak and Rattle 462

8.5.2 Objective Testing and Analysis of Squeak and Rattle 467

8.6 Control of Body Squeak and Rattle 471

8.6.1 Control Strategy during Vehicle Development 471

8.6.2 Body Structure‐Integrated Design and S&R Control 472

8.6.3 DMU Checking for Body S&R Prevention 476

8.6.4 Matching of Material Friction Pairs 477

8.6.5 Control of Manufacture Processes 478

8.6.6 Squeak and Rattle Issues for High Mileage Vehicle 478

8.6.7 Squeak and Rattle at High Mileage 479

Bibliography 480

9 Targets for Body Noise and Vibration 483

9.1 Target System for Vehicle Noise and Vibration 483

9.1.1 Period for Vehicle Development and Targets 483

9.1.2 Factors Influencing on Target Setting 485

9.1.3 Principles of Target Setting and Cascading 486

9.1.4 Principles of Modal Separation 488

9.1.5 Target System of Body NVH 489

9.2 NVH Targets for Vehicle‐Level Body 490

9.2.1 Vehicle‐Level Body NVH Targets 490

9.2.2 Vibration Targets for Vehicle‐Level Body 490

9.2.3 Noise Targets for Vehicle‐Level Body 491

9.3 NVH Targets for Trimmed Body 492

9.3.1 NVH Characteristics of Trimmed Body 492

9.3.2 Vibration Targets of Trimmed Body 493

9.3.3 Noise Targets for Trimmed Body 493

9.4 NVH Targets for Body‐in‐White 494

9.4.1 NVH Characteristics of BIW 494

9.4.2 Vibration Targets of BIW 495

9.4.3 Noise Target of BIW 496

9.5 NVH Targets for Body Components 496

9.5.1 Component‐Level Vibration Targets 497

9.5.2 Component‐Level Noise Target 497

9.5.3 Noise and Vibration Targets of Door 497

9.6 Execution and Realization of Body Targets 498

9.6.1 Control at Phase of Target Setting and Cascading 498

9.6.2 Target Checking at Milestones 499

9.6.3 CAE Analysis and DMU Checking 500

9.6.4 NVH Control for BIW 501

9.6.5 NVH Control for Trimmed Body and Full Vehicle 501

Bibliography 501

Index 503

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