Author
Subhendu K. Datta
Other affiliations: Cooperative Institute for Research in Environmental Sciences
Bio: Subhendu K. Datta is an academic researcher from University of Colorado Boulder. The author has contributed to research in topics: Scattering & Wave propagation. The author has an hindex of 25, co-authored 101 publications receiving 1484 citations. Previous affiliations of Subhendu K. Datta include Cooperative Institute for Research in Environmental Sciences.
Topics: Scattering, Wave propagation, Lamb waves, Isotropy, Composite plate
Papers published on a yearly basis
Papers
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TL;DR: In this article, the null field approach is used to solve for ground motion amplification on an inhomogeneity in an elastic half-space and various ways of doing this are discussed.
Abstract: Seismic ground motion amplification on alluvial valleys is studied in this paper. The alluvial valley is modelled as an elastic inhomogeneity in an elastic half-space. To solve for the ground motion amplification on such an inhomogeneity the null field approach is adopted. This requires modifications of the null field approach for an inhomogeneity inside a half-space and various ways of doing this are discussed.
2 citations
01 Jan 1991
TL;DR: In this paper, the authors present a systematic study of the influence of layering on the dispersion behavior of free Lamb waves in a cross-ply laminated plate, which can also be used to ultrasonically characterize the mechanical properties of the laminate plate.
Abstract: Although propagation of guided (Lamb) waves in a homogeneous isotropic plate has been studied extensively in the past, relatively few studies have been reported that deal with homogeneous anisotropic plate. In a recent paper Nayfeh and Chimenti [1] have reviewed the literature and they have presented results for dispersion of free Lamb waves in a homogeneous anisotropic plate. The present study is concerned with dispersion of free guided waves in a cross-ply laminated plate. Since laminated composite plates are finding usage in a variety of applications, there is a need to understand their response under dynamic loading. Of particular interest for this purpose is the characteristic dispersion of modes of propagation in a multi-layered laminated plate. This dispersion behavior influences the dynamic response and it can also be used to ultrasonically characterize the mechanical properties of the laminated plate. The motivation is to present a systematic study of the influence of layering on the dispersion behavior.
2 citations
2 citations
TL;DR: In this article, the axialsymmetric problem of Torsionswellen in an unendlichen, isotropen and homogenen elastischen Korper with einem kreisformigen Schlitz is investigated.
Abstract: In dieser Arbeit wird das axialsymmetrische Problem der Torsionswellen in einem unendlichen, isotropen und homogenen elastischen Korper mit einem kreisformigen Schlitz betrachtet. Es werden zwei Fredholmsche Integralgleichungen zweiter Art fur das gestreute Feld aufgestellt, welche sich bei kleinen Frequenzen zur iterativen Behandlung eignen. Die erste davon ist insofern vorteilhafter, als sie die Verschiebungs- und die Schubspannungsverteilung auf der Schlitzoberflache direkt liefert und bei iterativer Behandlung viel weniger Arbeit kostet als die zweite. Es werden Ausdrucke fur das Verschiebungs- und das Spannungsfeld an der Schlitzoberflache in Form von Potenzreihen des Frequenzfaktors erhalten. Ebenso wird ein Ausdruck fur den Spannungsintensitatsfaktor als Potenzreihe von α gewonnen.
2 citations
01 Jan 1987
TL;DR: In this paper, the effective elastic moduli and damping of a heterogeneous material by using elastic waves (propagating or standing) were determined for long wavelengths, and the wave speeds thus calculated are nondispersive and hence provide the values for the static effective elastic properties.
Abstract: One often determines the effective elastic moduli and damping of a heterogeneous material by using elastic waves (propagating or standing). Several theoretical studies show that for long wavelengths one can calculate the effective wave speeds of plane longitudinal and shear waves through a composite material. At long wavelengths the wave speeds thus calculated are nondispersive and hence provide the values for the static effective elastic properties. References to some of the recent theoretical and experimental studies can be found in [1–12]. The scattering formulations developed in [1–8] provide a means to obtain both the effective wave speeds and the damping caused by scattering.
2 citations
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1,197 citations
TL;DR: In this paper, the authors focus on variational and related methods for the overall properties of composites, such as fiber-reinforced composites or polycrystals, whose properties vary in a complicated fashion from point to point over a small, microscopic length scale, while they appear on average to be uniform.
Abstract: Publisher Summary This chapter focuses on variational and related methods for the overall properties of composites. A wide range of phenomena that are observable macroscopically are governed by partial differential equations that are linear and self-adjoint. This chapter is concerned with such phenomena for materials, such as fiber-reinforced composites or polycrystals, whose properties vary in a complicated fashion from point to point over a small, “microscopic” length scale, while they appear “on average” (that is, relative to the larger, macroscopic scale) to be uniform. This chapter treats the elastic behavior of composites, and emphasizes that a number of other properties (conductivity, viscosity of a suspension, etc.) are described by the same equations. Extensions to viscoelastic and thermoelastic behavior are presented, for both of which the variational characterization given is believed to be new. Problems, such as the resistance to flow of viscous fluid through a fixed bed of particles are mentioned, and a model problem that involves diffusion is presented in some detail. This displays the same difficulty in relation to divergence of an integral and is one problem of this type that has so far been approached variationally. Methods related to the Hashin–Shtrikman variational principle are also described in the chapter.
832 citations
Book•
11 Aug 2014
TL;DR: The semi-analytical finite element method (SAFE) has been used for guided wave modeling as discussed by the authors, which has been shown to be useful in the analysis and display of non-destructive testing.
Abstract: Preface Acknowledgments 1. Introduction 2. Dispersion principles 3. Unbounded isotropic and anisotropic media 4. Reflection and refraction 5. Oblique incidence 6. Waves in plates 7. Surface and subsurface waves 8. Finite element method for guided wave mechanics 9. The semi-analytical finite element method (SAFE) 10. Guided waves in hollow cylinders 11. Circumferential guided waves 12. Guided waves in layered structures 13. Source influence on guided wave excitation 14. Horizontal shear 15. Guided waves in anisotropic media 16. Guided wave phased arrays in piping 17. Guided waves in viscoelastic media 18. Ultrasonic vibrations 19. Guided wave array transducers 20. Introduction to guided wave nonlinear methods 21. Guided wave imaging methods Appendix A: ultrasonic nondestructive testing principles, analysis and display technology Appendix B: basic formulas and concepts in the theory of elasticity Appendix C: physically based signal processing concepts for guided waves Appendix D: guided wave mode and frequency selection tips.
823 citations
TL;DR: In this paper, the authors provide a state-of-the-art review of guided wave based structural health monitoring (SHM) and highlight the future directions and open areas of research in guided wave-based SHM.
Abstract: The paper provides a state of the art review of guided wave based structural health monitoring (SHM). First, the fundamental concepts of guided wave propagation and its implementation for SHM is explained. Following sections present the different modeling schemes adopted, developments in the area of transducers for generation, and sensing of wave, signal processing and imaging technique, statistical and machine learning schemes for feature extraction. Next, a section is presented on the recent advancements in nonlinear guided wave for SHM. This is followed by section on Rayleigh and SH waves. Next is a section on real-life implementation of guided wave for industrial problems. The paper, though briefly talks about the early development for completeness,. is primarily focussed on the recent progress made in the last decade. The paper ends by discussing and highlighting the future directions and open areas of research in guided wave based SHM.
664 citations
TL;DR: In this article, the authors provide a vision of ultrasonic guided wave inspection potential as we move forward into the new millennium and provide a brief description of the sensor and software technology that will make ultrasonic guidance wave inspection commonplace in the next century.
Abstract: Ultrasonic guided wave inspection is expanding rapidly to many different areas of manufacturing and in-service inspection. The purpose of this paper is to provide a vision of ultrasonic guided wave inspection potential aswe move forward into the new millennium. An increased understanding of the basic physics and wave mechanics associated with guided wave inspection has led to an increase in practical nondestructive evaluation and inspection problems. Some fundamental concepts and a number of different applications that are currently being considered will be presented in the paper along with a brief description of the sensor and software technology that will make ultrasonic guided wave inspection commonplace in the next century.
623 citations