Experimental and Computational Methods for Investigating Automotive Door Closure Sounds

ii Co-Authorship iv Acknowledgements v List of Figures ix List of Tables xiii List of Abbreviations xiv Nomenclature xv Chapter 1 1 1.1 Project Motivation 1 1.2 Scope of the Project 2 1.3 Organization of Thesis 2 Chapter 2 Literature Review 4 2.1 Acoustics 4 2.1.1 Simple Waveform 4 2.1.2 Complex Harmonic and Transient Waveforms 6 2.2 Vehicle Door Closure System Acoustics 8 2.2.1 Objective Study 8 2.2.2 Subjective Study 10 2.3 D21MC Automotive Door Closure System 12 2.4 Physiology of the Human Ear 16 2.5 Psychoacoustics 18 2.5.1 Sound Quality Metrics: Sharpness and Loudness 20 2.6 Computational Acoustic Processing 21 2.7 Summary 23 Chapter 3 Experimental Procedures and Data Analysis 25 3.1 Experimental Background 25 3.2 Experimental Equipment and Test Setup 25 3.2.1 Semi-Anechoic Chamber 25 3.2.2 Testing Apparatus 27 3.2.3 Microphone Array and Calibration 28 3.2.4 Data Acquisition System 29 3.2.5 Entrance Speed Calculation 30 vii 3.2.6 Sound Field Boundary Conditions 32 3.3 Experimental Procedure 35 3.4 Experimental Post-Processing Procedure and Methodologies 36 3.4.1 MATLAB Truncation Algorithm 36 3.4.2 1/3 Octave Bandwidth and A-Weighting Filters 39 3.4.3 Continuous Wavelet Transformation Analysis 44 3.5 Results and Analysis 45 3.5.1 Continuous Wavelet Transform Analysis 48 3.5.2 Sound Pressure Level versus 1/3 Octave Band 52 3.5.3 Sound Quality Metrics: Loudness and Sharpness 58 3.6 Conclusion 59 Chapter 4 Computational Procedures and Analysis 60 4.1 Computational Analysis and Methodology 60 4.2 Acoustic Simulation Workstation 61 4.3 Acoustic Simulation Methodologies 61 4.3.1 Finite Element Method 61 4.3.2 Boundary Element Method 62 4.3.3 Upper Frequency Limit 62 4.4 ANSYS Workbench 63 4.4.1 ANSYS ACT Acoustic Extension 63 4.5 SpaceClaim 64 4.6 Design Modeler: Structural Pre-Processing 65 4.7 Rigid Body Dynamics 68 4.7.1 Coil Spring to Torsional Spring Conversion 68 4.7.2 Model Assembly 69 4.7.3 Results and Analysis 70 4.8 Explicit Dynamics 71 4.8.1 Model Assembly 72 4.8.2 Mesh Generation 76 4.8.3 Results and Analysis 77 4.9 Transient Structural: Acoustic Simulation 79 4.9.1 Matrix Formulation 79 4.9.2 D21MC Acoustic Model Formulation 81 4.9.3 Element Types and Shape Function 86 viii 4.9.4 Model Discretization 87 4.9.5 Fluid Structure Interaction 89 4.9.6 Simulation Procedure 91 4.10 Computational Results