Download or read book Elastic Wave Propagation and Scattering in Polycrystals written by Anubhav Roy and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polycrystalline aggregates of randomly distributed grains are associated with a fluctuating elastic stiffness. These fluctuations or heterogeneities are potential scatterers to the elastic waves propagating through the polycrystalline microstructures. The scattering within these microstructures results in the attenuation of energy and a change in the phase velocity (wavespeed) of the incident wave. The attenuation and wavespeed are measurable quantities that reveal important information about the respective microstructure. Existing theoretical models apply a first-order Keller approximation or an equivalent first-order smoothing approximation (FOSA) to predict the attenuation and wavespeed in polycrystals. This dissertation presents a theoretical framework to investigate the effects of the third-order smoothing approximation (TOSA) on the attenuation and wavespeed estimates in transversely isotropic aggregates of randomly distributed cubic grains. \par The Keller approximation-based Unified Theory model is constructed in the spatial domain applicable to the propagation of plane waves. On the other hand, the equivalent FOSA-based model in the frequency domain, free from such plane wave assumptions, directly applies to modeling the diffuse fields as it considers a truncation of the mass operator series contained in an elastodynamic Dyson equation. This truncated Dyson series provides a statistical expectation of the Green's function dyadic used to model the respective mean field propagation. However, the existing FOSA-based model involves a Born approximation that limits its application to the stochastic scattering regime characterized by a transitional domain between the low and high frequencies. In this dissertation, the FOSA-based model has been extended for the first time to provide solutions beyond the Born approximation applicable for the full range of frequencies spanning from the Rayleigh (low frequencies) to the geometric regime (high frequencies). Independently generated FOSA-based estimates of wavespeed and attenuation in common metals like aluminum, iron, and lithium show reasonable agreement with the corresponding Unified Theory estimates. \par The FOSA-based model developed in the frequency domain is extended to incorporate two additional multiple scattering terms associated with the TOSA-based truncation to the Dyson series. The effects of including the TOSA-based terms are studied for the full range of frequencies from the Rayleigh to the geometric regime. These effects are quantified as a ratio between the estimates from the current model, including TOSA, and from the corresponding FOSA-based model. For low-frequency propagation under assumptions of Rayleigh limit, closed-form solutions of attenuation and wavespeed are obtained with and without considering Born approximation. The effects of including TOSA in the low frequencies have been studied for $758$ cubic metals with different degrees of elastic heterogeneities. The study in the low frequencies confirms a correlation between higher-order scattering and the degree of heterogeneity. Attenuation estimates are more sensitive than the wavespeed estimates to higher-order scattering. Moreover, the transverse or shear waves show a stronger sensitivity to higher-order scattering at low frequencies than longitudinal waves at the same frequencies. \par Significant effects of including the TOSA-based terms are observed in the high frequencies. Analogous to the FOSA-based estimates of wavespeed dispersion, the variation of attenuation in the geometric regime is found to be dependent on the incident mode while including the TOSA-based terms. Moreover, the attenuation and wavespeed dispersion in the geometric zone reveals a strong dependence on the degree of heterogeneity while including the TOSA-based terms. Nevertheless, both for longitudinal and transverse modes of propagation, the attenuation estimates start decreasing with increasing frequencies while considering the TOSA-based model. This can be attributed to a possible gain of resonance captured by the higher-order scattering events within the microstructure for propagation of high-frequency waves. This model can be applied to different microstructures possessing elastic heterogeneities to investigate the respective higher-order scattering effects. That may generate opportunities to offer a better agreement with the experimentally measured estimates in textured or porous microstructures. Beside the attenuation and wavespeed, analogous to the existing FOSA-based model, this model offers a direct scope of extension to provide other important estimates like the intensity of the scattered waves, diffusivity, etc.

Download or read book Elastic Wave Propagation in Polycrystals written by Ming Huang and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Elastic Wave Propagation Through Polycrystals written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Propagating elastic waves are commonly used to characterize nondestructively polycrystalline microstructure. To develop a fully quantitative characterization procedure, one needs a better understanding of what microstructural features most strongly influence the propagation and how these features appear in the measured, frequency dependent wave speed and attenuation. We report on our progress in a first principle investigation of these questions. We started with the equations of motion for elastic wave propagation and systematically developed a new approximation that is both well characterized and a potential improvement upon existing approximations. One of our objectives is studying the sensitivity of this approximation to changes in microstructural parameterization.

Download or read book Modern Problems in Elastic Wave Propagation written by Julius Miklowitz and published by John Wiley & Sons. This book was released on 1978-10-27 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gives an up-to-date, interdisciplinary account of important research findings, covering theoretical and practical applications of elastic wave propagation. Discusses waves in a linear, homogenous, isotropic boundaries, and modern problems in wave phenomena such as diffraction, scattering, reflection, and dispersion, as well as higher order effects. Uses analytical, numerical, and experimental methods.

Download or read book Theory of Elastic Wave Propagation and Its Application to Scattering Problems written by Terumi Touhei and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Elastic wave propagation applies widely across seismology, non-destructive testing, energy resource exploration, and site characterization. This starts with continuum mechanics, explaining stress and strain tensors in terms of mathematics and physics, and showing the derivation of equations for elastic wave motions. Green's function for applications of the elastic wave equation to practical engineering problems is emphasized. Elastic wave propagation in a half-space is covered, and the MUSIC algorithm is used to address inverse scattering problems. The companion website provides software with detailed solutions to the problems to suit graduate students"--

Download or read book Wave Scattering in Complex Media From Theory to Applications written by Bart A. van Tiggelen and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 637 pages. Available in PDF, EPUB and Kindle. Book excerpt: A collection of lectures on a variety of modern subjects in wave scattering, including fundamental issues in mesoscopic physics and radiative transfer, recent hot topics such as random lasers, liquid crystals, lefthanded materials and time-reversal, as well as modern applications in imaging and communication. There is a strong emphasis on the interdisciplinary aspects of wave propagation, including light and microwaves, acoustic and elastic waves, propagating in a variety of "complex" materials (liquid crystals, media with gain, natural media, magneto-optical media, photonic and phononic materials, etc.). It addresses many different items in contemporary research: mesoscopic fluctuations, localization, radiative transfer, symmetry aspects, and time-reversal. It also discusses new (potential) applications in telecommunication, soft matter and imaging.

Download or read book Elastic Wave Propagation Through Polycrystalline Ice With and Without Embedded Spherical Particle Inclusions written by Elizabeth Trautman and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the capabilities of additive manufacturing continue to grow, so does the need for reliable ways to nondestructively test those parts. Traditional ultrasonic inspection is often ineffective due to high acoustic impedance mismatch between immersion fluids and parts being tested. In order to overcome this issue, a new method called cryoultrasound is being developed. Cryoultrasound involves freezing a part, often having a complex geometry, into a puck of ice. The ice is manufactured to contain an appropriate volume of randomly mixed particles that alter the ice's acoustic properties to match that of the encased part, effectively creating a macroscopically continuous part to be ultrasonically inspected. To better understand the wave propagation through this complex ice composite, the fundamentals of wave propagation through polycrystalline ice and homogeneous ice containing particles is studied analytically. Weaver's analytical wave propagation model [10] is found to be appropriate for modeling the effects due to grain boundaries in the frequency range of interest. Multiple elastic moduli of ice are reported in literature. A series of differing moduli were evaluated using Weaver's model; it can be concluded that the choice of elastic modulus has a significant impact on attenuation, and the difference in attenuation increases with frequency. In addition, evaluation of ice micrographs identified an exponentially decaying function as an appropriate spatial correlation function. Using the correlation lengths derived from micrographs, Weaver's model [10] can be used to produce analytical results that correspond to experimental ice samples. Kanuan and Levin's effective field model [29] for spherical scatterers is used to characterize scattering due to embedded particles. From this model, the effect of particle size and volume fraction on attenuation is determined. Future work in analytical cryoultrasound includes an integrated model that accounts for both grain and particle scattering mechanisms.

Download or read book Numerical Simulations of Elastic Wave Scattering in Polycrystalline Materials written by Goutam Ghoshal and published by . This book was released on 2003 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wave Propagation written by Peter Markos and published by Princeton University Press. This book was released on 2008-04-01 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook offers the first unified treatment of wave propagation in electronic and electromagnetic systems and introduces readers to the essentials of the transfer matrix method, a powerful analytical tool that can be used to model and study an array of problems pertaining to wave propagation in electrons and photons. It is aimed at graduate and advanced undergraduate students in physics, materials science, electrical and computer engineering, and mathematics, and is ideal for researchers in photonic crystals, negative index materials, left-handed materials, plasmonics, nonlinear effects, and optics. Peter Markos and Costas Soukoulis begin by establishing the analogy between wave propagation in electronic systems and electromagnetic media and then show how the transfer matrix can be easily applied to any type of wave propagation, such as electromagnetic, acoustic, and elastic waves. The transfer matrix approach of the tight-binding model allows readers to understand its implementation quickly and all the concepts of solid-state physics are clearly introduced. Markos and Soukoulis then build the discussion of such topics as random systems and localized and delocalized modes around the transfer matrix, bringing remarkable clarity to the subject. Total internal reflection, Brewster angles, evanescent waves, surface waves, and resonant tunneling in left-handed materials are introduced and treated in detail, as are important new developments like photonic crystals, negative index materials, and surface plasmons. Problem sets aid students working through the subject for the first time.

Download or read book Elastic Wave Propagation in Random Media written by Christopher N. Layman and published by . This book was released on 2007 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hybrid Formulation of Wave Propagation and Scattering written by L.B. Felsen and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Workshop on Hybrid Formulations of Wave Propagat~on and Scattering underwent a sequence of iterations before emerging in the format recorded here. These iterations were caused by various administrative and logistical problems which need not be detailed. However, its direction being set initially, the iterations led to modifications of the original concept so that the final form was arrived at through an indirect approach. This circumstance may ex plain some possible deficiencies which might have been removed, had the final concept been implemented directly. The motivation arose from a perception that the newly restored interest, coupled with new developments, in hybrid methods employ ing progressing wave fields and oscillatory wave fields for time harmonic and transient guided propagation in manmade or general geo physical environments, and for scattering by targets and irregulari ties, merits exposure to the wider scientific community. Accord ingly, a meeting with highly tutorial content was envisaged. For administrative reasons, related to sponsorship and organizational structure, this objective could not be realized but, eventually, there emerged the possibility of convening an Advanced Research Workshop (ARW) under the auspices of the NATO Advanced Study Insti tute Series. The original concept was then modified to accommodate a Workshop, wherein state-of-the-art science is discussed by a relatively small group of specialists, instead of tutorial presenta tions of more basic material.

Download or read book Advanced Ultrasonic Methods for Material and Structure Inspection written by Tribikram Kundu and published by John Wiley & Sons. This book was released on 2013-03-01 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasonic signals are increasingly being used for predicting material behavior, both in an engineering context (detecting anomalies in a variety of structures) and a biological context (examining human bones, body parts and unborn fetuses). Featuring contributions from authors who are specialists in their subject area, this book presents new developments in ultrasonic research in both these areas, including ultrasonic NDE and other areas which go beyond traditional imaging techniques of internal defects. As such, both those in the biological and physical science communities will find this an informative and stimulating read.

Download or read book Elastic Wave Propagation written by F. McCarthy and published by Elsevier. This book was released on 2018-06-20 with total page 663 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains a timely collection of research papers on the latest developments in the ever-increasing use of elastic waves in a variety of contexts. There are reports on wave-propagation in various types of media: in both isotropic and anisotropic bodies; in homogeneous and inhomogeneous media; in media with cracks or inclusions in random media; and in layered composites.The bulk of the papers are concerned with propagation in elastic media, but also included are viscoelastic, thermoelastic and magneto-electroelastic wave propagation, as well as waves in porous and piezo-electric bodies. Consideration is given to propagation in bodies as diverse as stretched elastic strings to surfaces such as thin walled cylinders, and thin films under stress. Applications considered include the determination of the depth of cracks; analysis of ground motions generated by a finite fault in seismology; surface wave spreading on piezo-electric solids; and dynamical stress intensity factors. Most of the papers are theoretical in nature, and many are complemented by numerical studies. Also included are a general survey on experimental techniques, and reports on experimental work.The volume will be of interest to those who do theoretical studies of elastic wave propagation and to those who apply elastic waves whether in seismology, non-destructive testing, the fabrication of devices or underwater acoustics, etc.

Download or read book Acoustoelastic Scattering and Attenuation in Polycrystalline Materials written by Christopher M. Kube and published by . This book was released on 2014 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustoelasticity describes the phase velocity of a propagating wave in a nonlinear elastic material with a non-zero stress state. Traditionally, acoustoelasticity models assume that the wave propagates without energy loss or attenuating effects due to scattering or absorption of the wave in the material. However, scattering and attenuation effects are common in real metallic materials. In this case, the propagating medium for an ultrasonic wave consists of a continuous distribution of discrete grains with distinct orientations, i.e., a polycrystalline medium. The distinct orientations of the grains result in point to point differences in the elastic stiffness along the propagation path of the wave. The wave propagates with a phase velocity described by an average stiffness of the grains that have been previously in the propagation path. The next grain in the travel path will have a slightly different stiffness than the average and causes the grain boundary to scatter a portion of the wave's energy in various directions.

Download or read book Seismic Wave Propagation and Scattering in the Heterogeneous Earth Second Edition written by Haruo Sato and published by Springer Science & Business Media. This book was released on 2012-03-08 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic waves - generated both by natural earthquakes and by man-made sources - have produced an enormous amount of information about the Earth's interior. In classical seismology, the Earth is modeled as a sequence of uniform horizontal layers (or spherical shells) having different elastic properties and one determines these properties from travel times and dispersion of seismic waves. The Earth, however, is not made of horizontally uniform layers, and classic seismic methods can take large-scale inhomogeneities into account. Smaller-scale irregularities, on the other hand, require other methods. Observations of continuous wave trains that follow classic direct S waves, known as coda waves, have shown that there are heterogeneities of random size scattered randomly throughout the layers of the classic seismic model. This book focuses on recent developments in the area of seismic wave propagation and scattering through the randomly heterogeneous structure of the Earth, with emphasis on the lithosphere. The presentation combines information from many sources to present a coherent introduction to the theory of scattering in acoustic and elastic materials and includes analyses of observations using the theoretical methods developed. The second edition especially includes new observational facts such as the spatial variation of medium inhomogeneities and the temporal change in scattering characteristics and recent theoretical developments in the envelope synthesis in random media for the last ten years. Mathematics is thoroughly rewritten for improving the readability. Written for advanced undergraduates or beginning graduate students of geophysics or planetary sciences, this book should also be of interest to civil engineers, seismologists, acoustical engineers, and others interested in wave propagation through inhomogeneous elastic media.

Download or read book Spectral and Scattering Theory for Wave Propagation in Perturbed Stratified Media written by Ricardo Weder and published by Springer Science & Business Media. This book was released on 1990-12-14 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The propagation of acoustic and electromagnetic waves in stratified media is a subject that has profound implications in many areas of applied physics and in engineering, just to mention a few, in ocean acoustics, integrated optics, and wave guides. See for example Tolstoy and Clay 1966, Marcuse 1974, and Brekhovskikh 1980. As is well known, stratified media, that is to say media whose physical properties depend on a single coordinate, can produce guided waves that propagate in directions orthogonal to that of stratification, in addition to the free waves that propagate as in homogeneous media. When the stratified media are perturbed, that is to say when locally the physical properties of the media depend upon all of the coordinates, the free and guided waves are no longer solutions to the appropriate wave equations, and this leads to a rich pattern of wave propagation that involves the scattering of the free and guided waves among each other, and with the perturbation. These phenomena have many implications in applied physics and engineering, such as in the transmission and reflexion of guided waves by the perturbation, interference between guided waves, and energy losses in open wave guides due to radiation. The subject matter of this monograph is the study of these phenomena.

Download or read book Scattering of Elastic Waves by an Anisotropic Sphere with Application to Polycrystalline Materials written by Ata Jafarzadeh and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: