Noise And Vibration Control

by M L Munjal

Overview

Vibration and noise are two interrelated terms in the field of mechanical engineering. Vibration is caused by unbalanced inertial forces and moments whereas noise is the result of such vibrations. Noisy machines have always been a matter of concern. Lesser vibration ensures manufacturing to closer tolerances, lesser wear and tear, and longer fatigue life. Hence, a quieter machine is more cost-effective in the long run. It is now well understood that a quieter machine is in every way a better machine.This book deals with such industrial and automotive noise and vibration, their measurement and control. This textbook stresses on physical concepts and the application thereof to practical problems. The author's four decades of experience in teaching, research and industrial consultancy is reflected in the choice of the solved examples and unsolved problems.The book targets senior undergraduate students in mechanical engineering as well as designers of industrial machinery and layouts. It can readily be used for self-study by practicing designers and engineers.

Product Details

ISBN-13:	9789814434737
Publisher:	World Scientific / Indian Inst Of Science, India
Publication date:	08/21/2013
Series:	Iisc Lecture Notes Series , #3
Pages:	296
Product dimensions:	5.90(w) x 9.00(h) x 0.90(d)

Table of Contents

Dedication v

Series Preface vii

Preface ix

Chapter 1 Noise and Its Measurement 1

1.1 Plane Wave Propagation 2

1.2 Spherical Wave Propagation 4

1.3 Decibel Level 8

1.4 Frequency Analysis 9

1.5 Weighted Sound Pressure Level 12

1.6 Logarithmic Addition, Subtraction and Averaging 13

1.7 Directivity 18

1.8 Measurement of Sound Pressure Level 20

1.9 Loudness 23

1.10 Noise Limits in India 25

1.10.1 The noise pollution (regulation and control) rules, 2000 25

1.10.2 Permissible noise exposure for industrial workers 27

1.10.3 Noise limit for diesel generator sets 29

1.10.4 Noise limit for portable gensets 29

1.10.5 Noise limit for fire crackers 30

1.10.6 Noise limit for vehicles 31

1.11 Masking 33

1.12 Sound Level Meter 33

1.13 Microphones 34

1.14 Microphone Sensitivity 35

1.15 Intensity Meter 36

References 36

Problems in Chapter 1 37

Chapter 2 Vibration and Its Measurement 40

2.1 Vibration of Single Degree of Freedom System 41

2.1.1 Free vibration 42

2.1.2 Forced response 45

2.2 Vibration of a Multiple Degrees of Freedom System 48

2.2.1 Free response 49

2.2.2 Forced response of multi-DOF system 50

2.2.3 Modal expansion 50

2.3 Transmissibility 52

2.4 Critical Speed 58

2.5 Dynamical Analogies 60

2.6 Vibration of Beams and Plates 63

2.7 Vibration Measurement 69

2.8 Measurement of Damping Measurement of Sound Pressure Level 74

2.8.1 Logarithmic decrement method 74

2.8.2 Half-power bandwidth method 75

References 77

Problems in Chapter 2 78

Chapter 3 Vibration Control 80

3.1 Vibration Control at the Source 81

3.2 Vibration Isolators 83

3.2.1 Bonded rubber springs 84

3.2.2 Effect of compliant foundation 89

3.2.3 Pneumatic suspension 92

3.3 Dynamic Vibration Absorber (DVA) 94

3.4 Impedance Mismatch to Block Transmission of Vibration 98

3.4.1 Viscoelastic interlayer 99

3.4.2 Effect of blocking mass on longitudinal waves 101

3.4.3 Effect of blocking mass on flexural waves 106

3.5 Damping Treatments for Plates 107

3.5.1 Free layer damping (FLD) treatment 108

3.5.2 Constrained layer damping (CLD) treatment 109

3.6 Active Vibration Control 112

References 115

Problems in Chapter 3 116

Chapter 4 Acoustics of Rooms, Partitions. Enclosures and Barriers 118

4.1 Sound Field in a Room 118

4.2 Acoustics of a Partition Wall 125

4.3 Design of Acoustic Enclosures 132

4.4 Noise Reduction of a Partition Wall and Enclosure 138

4.5 Acoustics of Barriers 142

References 148

Problems in Chapter 4 148

Chapter 5 Mufflers and Silencers 151

5.1 Electro-Acoustic Modeling 152

5.2 Transfer Matrix Modeling 154

5.3 Simple Expansion Chamber (SEC) 168

5.4 Extended Tube Expansion Chamber (ETEC) 171

5.5 Extended Concentric Tube Resonator (ECTR) 175

5.6 Plug Muffler 178

5.7 Multiply Connected Muffler 180

5.8 Absorptive Ducts and Mufflers 182

5.9 Combination Mufflers 189

5.10 Acoustic Source Characteristics of I.C. Engines 190

5.11 Designing for Adequate Insertion Loss 196

5.12 Mufflers for High Pressure Vents and Safety Valves 201

5.13 Design of Muffler Shell and End Plates 203

5.14 Helmholtz Resonators 205

5.15 Active Noise Control in a Duct 209

5.16 Pressure Drop Considerations 212

References 215

Problems in Chapter 5 218

Chapter 6 Noise Control Strategies 221

6.1 Control of Noise at the Source 221

6.1.1 Select a quieter machine 221

6.1.2 Select lossy materials 222

6.1.3 Use quieter processes or tools 222

6.1.4 Reduce radiation efficiency 223

6.1.5 Maintain for quietness 224

6.1.6 Design of flow machinery for quietness 224

6.2 Control of Noise in the Path 226

6.3 Noise Control at the Receiver End 227

6.4 Noise Control of an Existing Facility 227

6.5 Estimation and Control of Compressor Noise 229

6.6 Estimation and Control of Noise of Fans and Blowers 233

6.7 Estimation and Control of Noise of Packaged Chillers 237

6.8 Estimation and Control of Noise of Cooling Towers 237

6.9 Estimation and Control of Pump Noise 239

6.10 Estimation and Control of Noise of Prime Movers 241

6.10.1 Turbines 241

6.10.2 Diesel engines 246

6.10.3 Electric motors 248

6.11 Jet Noise Estimation and Control 251

6.12 Estimation and Control of Gear Noise 256

6.13 Earthmoving Equipment Noise Estimation and Control 258

6.14 Impact Noise Control 259

6.15 Environmental Impact Assessment (EIA) 261

References 264

Problems in Chapter 6 265

Nomenclature 267

Index 271