These are the proceedings of the 18th International Symposium on Nonlinear Acoustics (ISNA).The ISNA series, held once every three years, is the premier symposium devoted to the field of nonlinear acoustics. Nonlinear acoustical phenomena appear when the sound amplitude is sufficiently large. Then the sound wave is deformed and shocks and sound of new frequencies are created. Earthquake and sonic booms are undesired nonlinear acoustical phenomena; nondestructive testing and cancer sound beam therapy are useful nonlinear acoustical applications. This book is unique in bringing into relief the common physical foundation of so different phenomena and applications.

This multi-contributed volume provides a practical, applications-focused introduction to nonlinear acoustical techniques for nondestructive evaluation. Compared to linear techniques, nonlinear acoustical/ultrasonic techniques are much more sensitive to micro-cracks and other types of small distributed damages. Most materials and structures exhibit nonlinear behavior due to the formation of dislocation and micro-cracks from fatigue or other types of repetitive loadings well before detectable macro-cracks are formed. Nondestructive evaluation (NDE) tools that have been developed based on nonlinear acoustical techniques are capable of providing early warnings about the possibility of structural failure before detectable macro-cracks are formed. This book presents the full range of nonlinear acoustical techniques used today for NDE. The expert chapters cover both theoretical and experimental aspects, but always with an eye towards applications. Unlike other titles currently available, which treat nonlinearity as a physics problem and focus on different analytical derivations, the present volume emphasizes NDE applications over detailed analytical derivations. The introductory chapter presents the fundamentals in a manner accessible to anyone with an undergraduate degree in Engineering or Physics and equips the reader with all of the necessary background to understand the remaining chapters. This self-contained volume will be a valuable reference to graduate students through practising researchers in Engineering, Materials Science, and Physics. Represents the first book on nonlinear acoustical techniques for NDE applications Emphasizes applications of nonlinear acoustical techniques Presents the fundamental physics and mathematics behind nonlinear acoustical phenomenon in a simple, easily understood manner Covers a variety of popular NDE techniques based on nonlinear acoustics in a single volume

This introductory text on the theory and applications of nonlinear acoustics, develops the theory on nonlinear acoustics from physical principles. The first half of the book develops the physical concepts, mathematical models and classical methods of solution that form the theoretical framework of nonlinear acoustics. Benchmark experiences are described and many applications are discussed in detail. The second half covers special topics and applications, both theory and experiment.

This textbook provides a unified approach to acoustics and vibration suitable for use in advanced undergraduate and first-year graduate courses on vibration and fluids. The book includes thorough treatment of vibration of harmonic oscillators, coupled oscillators, isotropic elasticity, and waves in solids including the use of resonance techniques for determination of elastic moduli. Drawing on 35 years of experience teaching introductory graduate acoustics at the Naval Postgraduate School and Penn State, the author presents a hydrodynamic approach to the acoustics of sound in fluids that provides a uniform methodology for analysis of lumped-element systems and wave propagation that can incorporate attenuation mechanisms and complex media. This view provides a consistent and reliable approach that can be extended with confidence to more complex fluids and future applications. Understanding Acoustics opens with a mathematical introduction that includes graphing and statistical uncertainty, followed by five chapters on vibration and elastic waves that provide important results and highlight modern applications while introducing analytical techniques that are revisited in the study of waves in fluids covered in Part II. A unified approach to waves in fluids (i.e., liquids and gases) is based on a mastery of the hydrodynamic equations. Part III demonstrates extensions of this view to nonlinear acoustics. Engaging and practical, this book is a must-read for graduate students in acoustics and vibration as well as active researchers interested in a novel approach to the material.

This book first introduced the theoretical foundation of nonlinear acoustics such as the basic equations of nonlinear acoustics followed by a statistical mechanics approach to nonlinear acoustics, then a curvilinear spacetime approach to nonlinear acoustics, then a gauge invariance approach to nonlinear acoustics, and application of chaos theory to nonlinear acoustics. Various formats of nonlinear acoustical imaging are given such as B/A nonlinear parameter acoustical imaging, fractal imaging, harmonics imaging, nonclassical nonlinear acoustical imaging, and modulation method in nonlinear acoustical imaging with their applications.

The aim of the present book is to present theoretical nonlinear aco- tics with equal stress on physical and mathematical foundations. We have attempted explicit and detailed accounting for the physical p- nomena treated in the book, as well as their modelling, and the f- mulation and solution of the mathematical models. The nonlinear acoustic phenomena described in the book are chosen to give phy- cally interesting illustrations of the mathematical theory. As active researchers in the mathematical theory of nonlinear acoustics we have found that there is a need for a coherent account of this theory from a unified point of view, covering both the phenomena studied and mathematical techniques developed in the last few decades. The most ambitious existing book on the subject of theoretical nonlinear acoustics is ”Theoretical Foundations of Nonlinear Aco- tics” by O. V. Rudenko and S. I. Soluyan (Plenum, New York, 1977). This book contains a variety of applications mainly described by Bu- ers’ equation or its generalizations. Still adhering to the subject - scribed in the title of the book of Rudenko and Soluyan, we attempt to include applications and techniques developed after the appearance of, or not included in, this book. Examples of such applications are resonators, shockwaves from supersonic projectiles and travelling of multifrequency waves. Examples of such techniques are derivation of exact solutions of Burgers’ equation, travelling wave solutions of Bu- ers’ equation in non-planar geometries and analytical techniques for the nonlinear acoustic beam (KZK) equation.