Automotive NVH Technology (eBook)

Preface 6
About the Organization Editing this Book 8
Acknowledgments 9
Contents 10
Editors and Contributors 11
1 Assessment of the Vehicle's Interior Wind Noise Due to Measurement of Exterior Flow Quantities in Early Project Phases 17
Abstract 17
1.1 Introduction 18
1.2 Methodology 19
1.3 Interpretation of Results 23
1.3.1 Larger Mirror Cap Rear Edge 23
1.3.2 Small Obstacles on A-Pillar 25
1.4 Summary 27
Acknowledgement 28
References 28
2 Sound Optimization for Downsized Engines 29
Abstract 29
2.1 Introduction 30
2.2 Strategies 31
2.2.1 Additional Synthesized Engine Pulses 31
2.2.2 Active Noise Cancellation 31
2.2.3 Engine Order Emphasis 33
2.3 Resulting Sound 36
2.4 Experiment 37
2.4.1 Method 37
2.4.2 Test Track 37
2.4.3 Engine Speed at Gear Shift 39
2.5 Results 40
2.6 Conclusion 41
Acknowledgement 42
References 43
3 Reducing Noise in an Electric Vehicle Powertrain by Means of Numerical Simulation 44
Abstract 44
3.1 Introduction 45
3.2 Common Approaches to Simulation 45
3.3 Simulation Methodology Used 47
3.3.1 Electromagnetic Motor Simulation 48
3.3.2 System Response 49
3.4 Candidate Project for Practical Implementation 51
3.5 Initial Simulation: Concept Design 51
3.6 Intermediate Simulation: Concept Selection 53
3.7 Detailed Simulation: Housing Design 55
3.8 Further Simulation: Refinement 56
3.9 Initial Testing 59
3.10 Outcome 59
3.11 Summary 60
Acknowledgement 60
References 60
4 Cylindrical Nearfield Acoustical Holography: Practical Aspects and Possible Improvements 62
Abstract 62
4.1 Introduction 62
4.2 Cylindrical Nearfield Acoustical Holography 63
4.2.1 NAH Formulation 63
4.2.2 Description of the Numerical Test Case 64
4.3 Practical Aspects of Cylindrical Holography 68
4.3.1 Hologram Length and Hologram Distance 68
4.3.2 Hologram Positioning Error 69
4.3.3 Hologram Measurement Noise 71
4.4 Possible Improvements: NAH with Compressive Sampling 72
4.5 Conclusions 75
Acknowledgement 76
References 76
5 Vibro-Acoustic Analysis of Geared Systems---Predicting and Controlling the Whining Noise 78
Abstract 78
5.1 Introduction 79
5.2 Static Transmission Error Computation and Robust Optimization of Tooth Profile Modifications 82
5.2.1 Static Transmission Error Computation 83
5.2.2 Optimization Fitness Function Establishment 83
5.2.3 Particle Swarm Optimization 84
5.2.4 Robustness Statistical Study 84
5.2.5 Results---Expected Static Transmission Errors and Actual Ones 85
5.2.6 Theoretical Versus Actual Tooth Topologies 86
5.2.7 Acoustic Benefits of the Optimization 87
5.3 Dynamic Response Computational Scheme Validation 88
5.4 Conclusion 92
Acknowledgement 93
References 93
6 Possibilities and Constraints for Lightweight in Exhaust Systems 95
Abstract 95
6.1 Introduction 96
6.2 Main Contributors to Lightweight Design 96
6.3 Acoustic Exhaust Valves---an Exhaust Mass Reduction Enabler 101
6.4 Weight Reduction and Active Exhaust Systems---Possibilities and Constraints 107
6.5 Conclusion 110
References 111
7 A Patch Transfer Function Approach for Combined Computational-Experimental Analysis of Vibro-Porous-Acoustic Problems 112
Abstract 112
7.1 Introduction 113
7.2 Problem Definition 115
7.3 Basic Concepts of the PTF Approach 116
7.3.1 Coupling Procedure 117
7.3.2 Coupling a Structural Domain with Two Fluid Layers 118
7.4 Experimental Characterisation of Porous Materials 119
7.4.1 Numerical Validation 120
7.5 Validation Study 123
7.5.1 Porous Part 123
7.5.2 Assembled System 124
7.6 Conclusions 128
Acknowledgement 129
References 129