Elastic Waves at High Frequencies


Book Description

John G. Harris intended to explain in this book the special techniques required to model the radiation and diffraction of elastic and surface waves. Sadly, he died before he could fulfil this ambition, but his plan has been brought to fruition by a team of his distinguished collaborators. The book begins with the basic underlying equations for wave motion and then builds upon this foundation by solving a number of fundamental scattering problems. The remaining chapters provide a thorough introduction to modern techniques that have proven essential to understanding radiation and diffraction at high frequencies. Graduate students, researchers and professionals in applied mathematics, physics and engineering will find that the chapters increase in complexity, beginning with plane-wave propagation and spectral analyses. Other topics include elastic wave theory, the Wiener–Hopf technique, the effects of viscosity on acoustic diffraction, and the phenomenon of channelling of wave energy along guided structures.




Low and High Frequency Asymptotics


Book Description

This volume focuses on asymptotic methods in the low and high frequency limits for the solution of scattering and propagation problems. Each chapter is pedagogical in nature, starting with the basic foundations and ending with practical applications. For example, using the Geometrical Theory of Diffraction, the canonical problem of edge diffraction is first solved and then used in solving the problem of diffraction by a finite crack. In recent times, the crack problem has been of much interest for its applications to Non-Destructive Evaluation (NDE) of flaws in structural materials.




Masters Theses in the Pure and Applied Sciences


Book Description

Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing. house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 25 (thesis year 1980) a total of 10,308 theses titles from 27 Canadian and 214 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. While Volume 25 reports theses submitted in 1980, on occasion, certain universities do report theses submitted in previous years but not reported at the time.







Elastic Waves in Composite Media and Structures


Book Description

New applications for composite materials are being developed at a rapid pace. However, their complex microstructures present considerable challenges for nondestructive testing and characterization. Ultrasonic waves provide quantitative means of nondestructive evaluation of these materials and structures. For this purpose, it is necessary to obtain







Scattering of Elastic Waves by Small Surface-breaking Or Subsurface Cracks in Three Dimensions


Book Description

The long-wavelength limit of elastic wave scattering by surface cracks in 3d is considered. It is shown that, if the crack is normal to the surface, the scattering can be described by two real parameters, one of which may be taken to be the crack size. The other therefore depends on shape, orientation, and burial depth. Many computed illustrations are given. It is concluded that the amount of information about cracks obtainable by low frequency elastic wave scattering is very limited.




Acoustic Wave Scattering from a Circular Crack


Book Description

The work reported was motivated by disagreement between the results obtained from two computations of scattering of an axially incident elastic p-wave on a circular crack. One calculation involves the direct solution of the Helmholtz integral equation, showing an oscillating total cross section. The other uses a program called MOOT, in which the elastic displacement near the crack is expanded in regular spherical eigenfunctions of the elastic wave equation. This calculation shows that the oscillations in total cross section disappear rapidly at high wave numbers. The conjecture that the basis for the MOOT expansion was inappropriate is examined by application to a test problem. Results indicate that there is no inadequacy in the spherical basis set. (LEW).