Structural Acoustics Determination And Random Phenomena

Description

From jet engine noise that generates vibrations in the structure of an aircraft, to the sound radiation from the hull of a ship or submarine that makes it identifiable, an understanding of structural acoustics is key in the design process in maritime, automotive, aerospace, and architectural engineering. Building on classic works in the field, Structural Acoustics: Deterministic and Random Phenomena presents fundamental concepts, relations, and simplified methods for calculating complex problems associated with vibrations and noise issues of automobiles, ships, submarines, and aircraft. This practical reference studies the response of structures and media that are coupled with a fluid and are under static, dynamic, and random loading.

Simplified solutions to complicated problems

Starting with a review of the fundamentals of acoustics and structural acoustics, the book discusses the response of the beams, plates, and shells that compose most built-up structures before providing methods for solving problems of built-up systems, including a procedure for computing the response of an elastic or viscoelastic media without resorting to a large computer program. Building on this analysis, the second section develops the analysis for random loading, which can also be applied to geophysical phenomena and viscoelastic media. Proceeding from the fundamental aspects of simple structures to more complicated cases with more involved loading, the book presents formulas and applications for random loading.

By providing a fundamental understanding of sound radiation in air and water, this book shows readers how to solve structural and acoustical problems. An important reference for those working in the area of acoustics and vibration analysis, it also includes computer programs for acoustical analysis available at www.crcpress.com.

Table of Contents

DETERMINISTIC PHENOMENA

General Overview of the Book
Introduction
Background
Overview of Random Structural Acoustics
Overview of Methods and Applications
Comparison of Methods Used in the Recent Literature
Applications
References

Fundamentals of Acoustics and Structural Acoustics
Introduction
Physical Phenomena in Linear Acoustics
Basic Assumptions and Equations in Linear Acoustics
Intensity and Energy
Free Sound Propagation
Sound Propagation with Obstacles
Free and Confined Waves
Sound Radiation and Vibration
Coupling of Structure/Medium (Interactions)
References
Glossary

Approximations for Added Mass and Radiation Damping
Definitions
References

Fundamentals of Structures and Analysis of Beams
Fundamentals of Structures
Beams
Plates
Shells
Three-Dimensional Variable Bodies
Analysis of Beams
Computer Programs
References

Unstiffened, Stiffened, Sandwich, and Composite Plates
Introduction
Unstiffened Plates
Rectangular Plates
Addition of Water Loading
Proposed Design Procedure for Simply Supported or Clamped Rectangular Plates under Uniform Impulsive Pressure
Cross-Stiffened and Sandwich Plates
Calculation of the Characteristics of Stiffened and Sandwich Plates
Composite Plates
Plate Applications
References

A Simplified Procedure for Built-up Structures
General Considerations
Potential Energy and Stiffness Coefficients
Equations of Motion and Basic Matrix
Effect of Fluid
Modal Impedances
Calculation of the Green’s Function
Potential Energy of Stretching and Shearing
Potential Energy of Bending and Twisting
Stiffness Coefficients
Example Calculations
References

Sound Patterns from Cylindrical Shells
Introduction
Basic Equations
General Equations for Shell Vibrating in Fluid and Containing Fluid
Frequencies and Mode Shapes
Effect of External or Internal Pressure on Natural Frequency
Relation to Buckling
Forced Vibration
Description of the Computer Program
Far Field Patterns for a Representative Case
References

Analysis of Three-Dimensional Media with Variable Properties
Introduction
Physical Characteristics of the Mathematical Model
Differential Equations of the Complex Medium
Approximate Solution
Solution for Nonhomogeneous Systems
References

RANDOM PHENOMENA

Linear Systems Equations
Impulse Response
Frequency Response Function
Statistics of the Response
Important Quantities Derivable from the Cross Spectrum
The Cross Spectrum in Terms of Fourier Transforms
The Conceptual Meaning of Cross Correlation, Cross Spectrum, and Coherence
References

Statistical Acoustics
Physical Concept of Transfer Function
Response in Terms of Green’s Functions
Statistical Differential Equations Governing the Sound Field
References

Statistics of Structures
Integral Relation for the Response
Computation of the Response in Terms of Modes
Coupled Structural Acoustic Systems
References

Random Radiation from Cylindrical Structures
Directivity Patterns
Multipole Expansion
Random Loading and Response
Computer Programs
References

Applications of Statistical Acoustics to Near Field–Far Field Problems
The Near Field–Far Field Problem
Parrent’s Solution for the Plane
Other Applications of the Parrent Equation
Solution Using a Single Integration with Known Coherence
Determination of Far Field from Near Field Autospectrum Alone and the Inverse Far Field–Near Field Problem
Simplification of Equations for Plane Waves
Methods for Computing Far Field from Near Field Acceleration
Application to Prediction of Radiation
Inverse Method Calculation: Development of the Field in
Terms of Point Sources
Point Force Calculations
References

Scale Models of Random Loading and Response
Approximate Formulation of the Modeling Laws
Damping
More General Formulation of Modeling Laws
Some General Considerations in Modeling
References

Index