Wave Propagation in Dissipative Materials
Wave Propagation in Dissipative Materials

Author: B.D. Coleman

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 143

ISBN-13: 3642886914

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Common experience reveals two basic aspects of wave propagation. First, while preserving their identity and travelling at definite speeds, sounds finally die out. Second, weak sounds may combine to form strong noises. Theories of acoustic propagation have succeeded in representing these aspects of experience separately, but never combined as in nature. The classical theories of sound in perfect fluids and elastic solids easily yield common speeds of propagation for plane infinitesimal disturbances, but no damping. Moreover, within EULER'S theory of the perfect fluid, or its generalization, the GREEN-KIRCHHOFF-KELVIN theory of finite elasticity, weak waves may grow stronger and become shock waves, which propagate according to more complicated but equally definite principles. Effects of internal damping are easily added for theories of infinitesimal deformation, but for finite motions a dead end was reached about sixty years ago. Indeed, in 1901 DUHEM proved that according to the NAVIER-STOKES theory of fluids acceleration waves and waves of higher order cannot exist, and for shock waves he claimed a similar result, which has since been shown to be valid subject to certain qualifications. So as to save the phenomena of sound and noise, as was necessary if the NAVIER-STOKES theory was to deserve the place proposed for it as a refinement upon EULER'S theory, DUHEM introduced the concept of "quasi-wave", a region of rapid but continuous transition.

Data Reduction Techniques for Analysis of Wave Propagation in Dissipative Materials
Data Reduction Techniques for Analysis of Wave Propagation in Dissipative Materials

Author: James L. Drake

Publisher:

Published: 1968

Total Pages: 84

ISBN-13:

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This report discusses two analytical approaches to be used in future studies of stress-wave propagation in rock. The first of the discussions is the development of a method of Fourier analysis of waveforms, the Impulse Train technique. This technique makes use of a discontinuous derivative and the properties of the Dirac delta function for the numerical evaluation of the Fourier transform of a measured time history. The second describes a method whereby a possible stress-strain curve can be deduced from particle velocity histories. Incremental steps in stress are assumed to travel at a velocity determined by the slope of the material stress-strain curve at the stress level of the increment. Equations are derived for the relation of particle velocity to strain and stress. Fortran computer programs for each of the analytical discussions are included as appendixes. (Author).

Wave Propagation in Materials and Structures
Wave Propagation in Materials and Structures

Author: Srinivasan Gopalakrishnan

Publisher: CRC Press

Published: 2016-11-03

Total Pages: 861

ISBN-13: 1315354896

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This book focuses on basic and advanced concepts of wave propagation in diverse material systems and structures. Topics are organized in increasing order of complexity for better appreciation of the subject. Additionally, the book provides basic guidelines to design many of the futuristic materials and devices for varied applications. The material in the book also can be used for designing safer and more lightweight structures such as aircraft, bridges, and mechanical and structural components. The main objective of this book is to bring both the introductory and the advanced topics of wave propagation into one text. Such a text is necessary considering the multi-disciplinary nature of the subject. This book is written in a step-by step modular approach wherein the chapters are organized so that the complexity in the subject is slowly introduced with increasing chapter numbers. Text starts by introducing all the fundamental aspects of wave propagations and then moves on to advanced topics on the subject. Every chapter is provided with a number of numerical examples of increasing complexity to bring out the concepts clearly The solution of wave propagation is computationally very intensive and hence two different approaches, namely, the Finite Element method and the Spectral Finite method are introduced and have a strong focus on wave propagation. The book is supplemented by an exhaustive list of references at the end of the book for the benefit of readers.

Elastic Wave Propagation in Structures and Materials
Elastic Wave Propagation in Structures and Materials

Author: Srinivasan Gopalakrishnan

Publisher: CRC Press

Published: 2022-08-29

Total Pages: 430

ISBN-13: 1000636488

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Elastic Wave Propagation in Structures and Materials initiates with a brief introduction to wave propagation, different wave equations, integral transforms including fundamentals of Fourier Transform, Wavelet Transform, Laplace Transform and their numerical implementation. Concept of spectral analysis and procedure to compute the wave parameters, wave propagation in 1-D isotropic waveguides, wave dispersion in 2-D waveguides is explained. Wave propagation in different media such as laminated composites, functionally graded structures, granular soils including non-local elasticity models is addressed. The entire book is written in modular form and analysis is performed in frequency domain. Features: Brings out idea of wave dispersion and its utility in the dynamic responses. Introduces concepts as Negative Group Speeds, Einstein’s Causality and escape frequencies using solid mathematical framework. Discusses the propagation of waves in materials such as laminated composites and functionally graded materials. Proposes spectral finite element as analysis tool for wave propagation. Each concept/chapter supported by homework problems and MATLAB/FORTRAN codes. This book aims at Senior Undergraduates and Advanced Graduates in all streams of engineering especially Mechanical and Aerospace Engineering.