Vehicle refinement : controlling noise and vibration in road vehicles

Contents Acknowledgements ix Preface x About the author xii 1 Vehicle refinement: purpose and targets 1 1.1 Introduction and definitions 1 1.2 Scope of this book 2 1.3 The purpose of vehicle refinement 3 1.4 How refinement can be achieved in the automotive industry 5 1.5 The history of vehicle refinement: one representative 20-year example 6 1.6 Refinement targets 9 References 15 2 The measurement and behaviour of sound 17 2.1 How sound is created and how it propagates 17 2.2 Making basic noise measurements: the sound level meter, recording sound 33 2.3 Making basic noise measurements: the decibel scale, frequency and time weightings 43 2.4 Analysis and presentation of noise data 48 2.5 Sound power level, sound intensity level, sound pressure level 59 References 70 Appendix 2A: Introduction to logarithms 72 3 Exterior noise: assessment and control 74 3.1 Pass-by noise homologation 74 3.2 Noise source ranking 81 3.3 Air intake systems and exhaust systems: performance and noise effects 84 3.4 Tyre noise 136 References 140 Appendix 3A: Valve and port geometry 144 viii Contents 4 Interior noise: assessment and control 145 4.1 Subjective and objective methods of assessment 145 4.2 Noise path analysis 151 4.3 Measuring the sound power of IC engines and other vehicle noise sources 159 4.4 Engine noise 173 4.5 Road noise 179 4.6 A note on aerodynamic (wind) noise 181 4.7 A note on brake noise 182 4.8 A note on squeak, rattle and tizz noises 183 4.9 Control of sound through absorption within porous materials 184 4.10 Control of sound by minimising transmission through panels 194 References 211 Appendix 4A: Some background information on systems 215 Appendix 4B: The convolution integral 217 Appendix 4C: The covariance function, correlation and coherence 220 Appendix 4D: The frequency response function 225 Appendix 4E: Plane waves in a tube with a termination impedance 227 Appendix 4F: The derivation of the linearised mass conservation equation 231 Appendix 4G: The derivation of the non-linear (and linearised) inviscid Euler equation 233 5 The measurement and behaviour of vibration 234 5.1 Making basic vibration measurements 234 5.2 Laser-based vibration measurements 238 5.3 Analysis and presentation of vibration data: quantifying vibration 240 5.4 Modes of vibration and resonance 248 5.5 Modal analysis 264 References 268 6 Sources of vibration and their control 269 6.1 Introduction 269 6.2 Damping of vibrations 269 6.3 Vibration isolation and absorption 287 6.4 Engine and drivetrain vibrations 299 6.5 Vehicle and chassis vibrations: ride quality 334 References 338 Index 341