1st Edition

Structural Acoustics Deterministic and Random Phenomena

By Joshua E. Greenspon Copyright 2011
    297 Pages 63 B/W Illustrations
    by CRC Press

    297 Pages 63 B/W Illustrations
    by CRC Press

    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.

    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

    Biography

    Dr. Greenspon received his Bachelor’s, Master’s, and Doctoral degrees from The Johns Hopkins University. While studying for his doctoral degree, he also taught Applied Mechanics for several years at the University. Upon completion of his course work, he was employed by the David Taylor Model Basin to do studies on ship vibrations. He completed the original research for his doctoral thesis in vibrations of thick cylindrical shells.

    He subsequently worked for the Martin Marietta Corporation doing research in panel flutter. He established a consultancy firm—JG Engineering Research Associates—and continued doing research under contract to the United States Army and Navy, in the areas of vibrations, sound radiation, and structures subject to blast and fragmentation.

    Dr. Greenspon was awarded the Silver Medal in Engineering Acoustics by The Acoustical Society of America for the solution of underwater radiation and scattering problems. He also served as an Associate Editor of the Journal of the Acoustical Society of America for 20 years. He was a member of the Acoustical Society of America, the American Society of Mechanical Engineers, the Society of Naval Architects and Marine Engineers, and the American Institute of Aeronautics and Astronautics.

    Dr. Greenspon passed away in February 2011, a few months before the publication of this book.

    "…the culmination of a long-term research program in the field of structural acoustics undertaken by one of the most distinguished pioneers in this field. … a valuable addition to the meager number of books in structural acoustics. It complements Junger and Feit’s book Sound structures and their Interactions. The book is targeted equally to graduate students and acoustical researchers."
    —S. I. Hayek, Penn State University, State College, USA