Book•
Acoustic Fields and Waves in Solids
01 Jan 1973-
TL;DR: In this article, the authors apply the material developed in the Volume One to various boundary value problems (reflection and refraction at plane surfaces, composite media, waveguides and resonators).
Abstract: This work, part of a two-volume set, applies the material developed in the Volume One to various boundary value problems (reflection and refraction at plane surfaces, composite media, waveguides and resonators). The text also covers topics such as perturbation and variational methods.
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27 Feb 2013
TL;DR: In this article, the authors highlight the need for the non-destructive testing (NDT) of aircraft, petrochemical and naval structures and highlight the most appropriate NDT technique to plate-like structures.
Abstract: The motivation of the this work is highlighted by the need for the Non-Destructive Testing (NDT) of aircraft, petrochemical and naval structures. Functioning conditions of these structures and the time factor can lead to serious damage. The most appropriate NDT technique to plate-like structures seems to be guided ultrasonics Lamb waves [1]. These waves can carry out energy over long distances and have the potential to be sensitive to several types of defects. Consequently, their use allows fast and efficient inspections of industrial structures. However, the multimode and dispersive nature of Lamb modes make the interpretation of the received ultrasonic signals complex and ambiguous in presence of discontinuities. Moreover, the generation and reception of a selected Lamb mode by transducers remains a difficult task due to the complexity of guided waves.
01 Jan 1999
TL;DR: In this paper, the authors proposed a parametric approach to identify the arrival time of different modes and their reflections and to take into account the effect of both dispersion and diffraction.
Abstract: Ultrasonic laser techniques are widely used in non-destructive inspection. Owing to theirs numerous advantages [1], these contactless methods allow characterization of anisotropic and viscoelastic media [2, 3]. Ultrasonic bulk waves, whatever the longitudinal or transverse mode, or their multiple reflections propagating back and forth through the plates, can been detected by interferometric laser techniques. But, how to obtain informations on the stiffness and viscosity tensors? The spectrum ratio between a mode and its reflection allows to get these data. Nevertheless it requires to identify the arrival time of the different modes and of their reflections and to take into account the effect of both dispersion and diffraction. The adopted solution is a parametric method which allows to set free from these problems.
10 Feb 2016
TL;DR: In this paper, the authors explored the feasibility of using feature guided waves (FGW) for rapid screening of 90˚ composite laminated bends for high performance structures such as aircraft and large wind turbine blades.
Abstract: Fiber reinforced composite materials have been increasingly used in high performance structures such as aircraft and large wind turbine blades. 90◦ composite bends are common in reinforcing structural elements, which are prone to defects such as delamination, crack, fatigue, etc. Current techniques are based on local inspection which makes the whole bend area scanning time consuming and tedious. This paper explores the feasibility of using feature guided waves (FGW) for rapid screening of 90◦ composite laminated bends. In this study, the behavior of the bend-guided wave in the anisotropic composite material is investigated through modal studies by applying the Semi-Analytical Finite Element (SAFE) method, also 3D Finite Element (FE) simulations are performed to visualize the results and to obtain cross validation. To understand the influence of the anisotropy, three-dimensional dispersion surfaces of the guided modes in flat laminated plates are obtained, showing the dependence of the phase velocity with ...
01 Dec 1981
TL;DR: In this paper, the first-born approximation to solutions of a time-domain integral equation was used to obtain the backscattered dilatation wave response from spherical and cylindrical inclusions of arbitrary homogeneous anisotropic elastic material embedded within a homogeneous isotropic host.
Abstract: : The first Born approximations to solutions of a time-domain integral equation were used to obtain the backscattered dilatation wave response from spherical and cylindrical inclusions of arbitrary homogeneous anisotropic elastic material embedded within a homogeneous isotropic host. For large ka, where the validity of the first Born approximation is questioned, the time waveform responses from cylinders and spheres are markedly different; for ka approaches limit of 0, they have identical time form with amplitudes dependent upon the volume of the scatterer. Excellent agreement with an experimental result for scattering from a cylindrical void was obtained for a value of ka = 0.32. A 'transparency condition' was obtained, allowing that for certain combinations of both density and stiffness of the scatterer and host, the scatterer appears transparent to the incoming wave in the first Born approximation.
TL;DR: In this article, the authors proposed a method to solve the problem of the lack of a suitable solution to the problem by using the information of the user's interaction with the system.
Abstract: 인체 연조직에서 기계적인 진동의 전달 특성은 조직의 탄성 특성에 의존한다. 연조직의 진동 특성으로부터 암이나 종양을 진단할 수 있기 때문에 진동의 전달 특성에 대한 연구는 중요한 의미를 가진다. 이 논문은 연조직의 표면에 위치하는 여러 형태의 응력 진동원에 의해 연조직 내에 발생되는 변위 패턴을 분석하고 비교하였다. 진동원으로는 수직하중, 접선하중, 그리고 면외전단하중이 고려되었다. 점탄성 단일층에서의 변위에 대한 이론적 표현식을 구하였고, 수치계산은 반공간 및 무한평판조직에서 수행되었다. 그리고 유한크기조직에서의 변위패턴을 유한요소법으로 시뮬레이션하였다. 응력 형태, 진동원 크기 및 주파수, 그리고 경계면이 변위에 미치는 영향이 분석되었다.
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Book•
01 Jan 1985
TL;DR: In this paper, the physical properties of crystals systematically in tensor notation are presented, presenting tensor properties in terms of their common mathematical basis and the thermodynamic relations between them.
Abstract: First published in 1957, this classic study has been reissued in a paperback version that includes an additional chapter bringing the material up to date. The author formulates the physical properties of crystals systematically in tensor notation, presenting tensor properties in terms of their common mathematical basis and the thermodynamic relations between them. The mathematical groundwork is laid in a discussion of tensors of the first and second ranks. Tensors of higher ranks and matrix methods are then introduced as natural developments of the theory. A similar pattern is followed in discussing thermodynamic and optical aspects.
8,520 citations
Book•
01 Jan 1960
TL;DR: In this paper, the authors present a model for waveguide decomposition in terms of waveguide discontinuities and waveguides and cavities, and apply it to artificial dielectrics.
Abstract: Preface. Basic Electromagnetic Theory. Green's Functions. Transverse Electromagnetic Waves. Transmission Lines. Waveguides and Cavities. Inhomogeneously Filled Waveguides and Dielectric Resonators. Excitation of Waveguides and Cavities. Variational Methods for Waveguide Discontinuities. Periodic Structures. Integral Transform and Function-Theoretic Techniques. Surface Waveguides. Artificial Dielectrics. Mathematical Appendix. Name Index. Subject Index. About the Author.
4,393 citations
293 citations