Designing Quiet Structures: A Sound Power Minimization Approach
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Table of contents
- Cover
- DESIGNING QUIET STRUCTURES: A Sound Power Minimization Approachiii
- Copyright Pageiv
- Contentsv
- PREFACEix
- ACKNOWLEDGMENTSxiii
- CHAPTER 1. BASIC EQUATIONS OF ACOUSTICS1
- 1.1 Derivation of the Wave Equation1
- 1.2 The Helmholtz Equation for Time–Harmonic Vibrations7
- 1.3 Boundary Conditions for Acoustic Boundary Value Problems9
- 1.4 The Time–Averaged Acoustic Power Output of a Vibrating Structure10
- 1.5 The Inhomogeneous Form of the Helmholtz Equation and Green's Functions12
- 1.6 The Free–Space Green's Function13
- 1.7 The Kirchhoff–Helmholtz Equation15
- 1.8 Sound Radiation from a Very Small Source17
- References20
- CHAPTER 2. A LUMPED PARAMETER MODEL FOR THE ACOUSTIC RADIATION PROBLEM23
- 2.1 Introduction24
- 2.2 Basic idea of the lumped parameter model25
- 2.3 Example of a Radially and Transversely Oscillating Sphere29
- 2.4 Integral Solution for the Acoustic Field of a Vibrating Structure Using the Free-Space Green's F37
- 2.5 Integral Solution for the Acoustic Field of a Vibrating Structure Using the Green's Function of38
- 2.6 Lumped Parameter Model for the Acoustic Field of a Vibrating Structure39
- 2.7 Lumped Parameter Model for the Acoustic Power Output42
- 2.8 Characterizing the Error in the Lumped Parameter Approximation44
- 2.9 Convergence of the Lumped Parameter Model as a Function of Element Size53
- References55
- Laboratory Exercise: Radiation From Monopole and Dipole Sources at Low Frequencies57
- CHAPTER 3. NUMERICAL SOLUTION OF THE ACOUSTIC RADIATION PROBLEM59
- 3.1 General Methods for Approximately Satisfying the Boundary Condition61
- 3.2 Conversion of Structural Displacements to Elemental Volume Velocities76
- 3.3 Radiation from Different Types of Structural Components77
- 3.4 Implementation of the Volume Velocity Matching Scheme81
- 3.5 Computing Acoustic Power Output84
- 3.6 Calculation of the Resistance Matrix89
- 3.7 Numerical Example Problems91
- References101
- Laboratory Exercise: Compiling and Running the Program POWER for an Example Problem102
- CHAPTER 4. EXPERIMENTAL MEASUREMENT OF THE RESISTANCE MATRIX105
- 4.1 The Resistance Probe106
- 4.2 Measurement of the Resistance Matrix112
- 4.3 Example Problems113
- References122
- Laboratory Exercise #1: Calibration of an Acoustic Surface Resistance Probe122
- Laboratory Exercise # 2: Surface Resistance Measurements on Simple Geometric Shapes124
- Laboratory Exercise # 3: Comparison of Experimental Predictions to Numerical Calcu- lations126
- CHAPTER 5. POWER OUTPUT COMPUTATIONS USING THE RESISTANCE MATRIX129
- 5.1 Frequency Dependence of the Resistance Matrix129
- 5.2 Radiation Efficiency of Vibrational Mode Shapes138
- References142
- Problems142
- Laboratory Exercise #1: Measurement of the Surface Velocity Profile of a Vibrating Structure142
- Laboratory Exercise #2: Computation of the Acoustic Power Output144
- Laboratory Exercise #3: Measurement of the Acoustic Power Output (optional)144
- CHAPTER 6. MINIMIZING SOUND POWER USING MATERIAL TAILORING145
- 6.1 Defining the Objective Function, Design Parameters and Constraints147
- 6.2 Analytical Sensitivities for Optimization150
- 6.3 Reduction in the Sound Power of a Simply Supported, Baffled Beam Using Masses154
- 6.4 Reducing the Radiation Efficiency of the Structural Resonances of a Plate159
- References173
- Problems175
- Laboratory Exercise #1: Reducing the Radiation Efficiency of a Structural Resonance of a Plate175
- CHAPTER 7. ACTIVE CONTROL OF RADIATED ACOUSTIC POWER179
- 7.1 Optimum Solution for the Control Source Amplitudes180
- 7.2 Numerical Example Problems186
- 7.3 Elemental Volume Velocity Control190
- 7.4 More Realistic Simulation of Active Control196
- References197
- Problems198
- Laboratory Exercise #1: Optimization Techniques for Reducing Acoustic Sound Power Via Active Control198
- CHAPTER 8. CHARACTERIZING AND CONTROLLING SOUND IN AN ENCLOSURE201
- 8.1 Calculating the Acoustic Potential Energy in an Enclosure202
- 8.2 Rewriting the Potential Energy in Terms of Elemental Volume Velocities214
- 8.3 Actively Controlling the Acoustic Potential Energy in an Enclosure220
- 8.4 Numerical Example Problem221
- References224
- Problems224
- Laboratory Exercise #1: Numerical Simulation of Active Control in an Enclosure224
- Laboratory Exercise #2: Experimental Validation of the Predicted Reductions in the Potential Energy225
- APPENDIX USING THE COMPUTER PROGRAMS227
- A. 1 Input to the Program VV228
- A.2 Output from the Program VV232
- A.3 Input to the Program POWER234
- A.4 Output from the Program POWER235
- A.5 Discussion of the Computer Program POWER236
- References237
- Index239
- WARNING245
This book is the first of its kind. It provides the reader with a logical and highly quantitative means of including noise as a parameter in the early design stages of a machine or structure. The unique and unified methodology builds upon the familiar disciplines of acoustics, structural dynamics and optimization. It also exemplifies the art of simplification - the essence of all good engineering design. =
Strategies for designing quiet structures require extensive analytical and experimental tools. For computing the sound power from complex structures the authors recommend a new 3-D, lumped parameter formulation. Not only this, they also include, on an accompanying companion website, an original numerical program POWER. This fully developed, user-friendly program can be applied generally to noise-control-by-design problems. Detailed instructions for running the application are given in the appendix as well as several sample problems to help the user get started. =
The authors also describe a new instrument: a specially developed resistance probe used to measure a structure=92s acoustic surface resistance. As an example, the procedure is outlined for measuring the valve cover of an internal combustion engine. Indeed, throughout the book the reader is presented with actual experiments, numerical and physical that they can replicate in their own laboratory.
This is a must-have book for engineers working in industries that include noise control in the design of a product. Its practical and didactic approach also makes it ideally suited to graduate students.
Key Features
* First text covering the design of quiet structures
* Written by two of the leading experts in the world in the area of noise control
* Strong in its integration of structural dynamics, acoustics, and optimization theory
* Accompanied by a computer program that allows the computation of sound power
* Presents numerous applications of noise-control-by-design methods as well as methods for enclosed and open spaces
* Each chapter is supported by homework problems and demonstration experiments
Strategies for designing quiet structures require extensive analytical and experimental tools. For computing the sound power from complex structures the authors recommend a new 3-D, lumped parameter formulation. Not only this, they also include, on an accompanying companion website, an original numerical program POWER. This fully developed, user-friendly program can be applied generally to noise-control-by-design problems. Detailed instructions for running the application are given in the appendix as well as several sample problems to help the user get started. =
The authors also describe a new instrument: a specially developed resistance probe used to measure a structure=92s acoustic surface resistance. As an example, the procedure is outlined for measuring the valve cover of an internal combustion engine. Indeed, throughout the book the reader is presented with actual experiments, numerical and physical that they can replicate in their own laboratory.
This is a must-have book for engineers working in industries that include noise control in the design of a product. Its practical and didactic approach also makes it ideally suited to graduate students.
Key Features
* First text covering the design of quiet structures
* Written by two of the leading experts in the world in the area of noise control
* Strong in its integration of structural dynamics, acoustics, and optimization theory
* Accompanied by a computer program that allows the computation of sound power
* Presents numerous applications of noise-control-by-design methods as well as methods for enclosed and open spaces
* Each chapter is supported by homework problems and demonstration experiments