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Subhendu K. Datta

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.


Papers
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Journal ArticleDOI
TL;DR: In this article, the effect of layering on the response of a multilayered laminated plate in both time and frequency domains to a line source on the surface of the plate was analyzed.

11 citations

Book ChapterDOI
01 Jan 1987
TL;DR: In this paper, the problem of elastic wave scattering by planar cracks near or at the free surface of a semi-infinite elastic homogeneous medium has been studied theoretically by many authors.
Abstract: Problems of elastic wave scattering by surface-breaking and near-surface cracks are of considerable current interest for ultrasonic nondestructive evaluation. Ultrasonic scattering by planar cracks near or at the free surface of a semi-infinite elastic homogeneous medium has been studied theoretically by many authors. References to recent papers on this subejct can be found in [1], [2] and [3]. Some experimental works on surface-breaking normal planar cracks have also appeared ([4] – [6]).

10 citations

Journal ArticleDOI
TL;DR: In this article, a variational formulation has been used for deriving the dispersion equation governing guided elastic waves in laminated plates, which is a matrix eigenvalue problem that can be solved for the wavenumbers at given frequencies or for the frequencies at given wavelengths.
Abstract: Analysis of wave propagation and scattering in a composite plate is complicated by the anisotropic properties of the laminae. An accurate computation of the wave field excited by transient sources in such a plate is required in order to characterize the anisotropic stiffness properties of the laminae and for ultrasonic evaluation of delamination defects. Here, a variational formulation has been used for deriving the dispersion equation governing guided elastic waves in laminated plates. The equation is a matrix eigenvalue problem that can be solved for the wavenumbers at given frequencies or for the frequencies at given wavenumbers. For accurate evaluation of the eigenvalues it is necessary to have a large number of sublayers, which results in large matrices and is not computationally efficient. However, the matrix formulation combined with analytical refinement is shown to give fairly accurate results that agree well with experiments. In this article, results for guided wave dispersion and the inverse pr...

10 citations

Journal ArticleDOI
TL;DR: In this paper, a combined finite elements and eigenfunction expansion technique for solving scattering problems involving multiple scattering as well as complex geometries is presented. But the results presented here are for homogeneous materials, the method can readily be extended to composite materials.
Abstract: : At present ultrasonic techniques for characterizing defects are being explored vigorously at various research centers around the world. Currently, the ultrasonic approach to defect sizing and characterization is beginning to find great favor for in- or out-of-service use. A recent review of practical ultrasonic nondestructive evaluation is referred. Because of recent advances in experimental ultrasonic technology, increasing demands are being put on quantitative theoretical modeling of scattering of ultrasonic (elastic) waves by cracks, cavities and other material inhomogeneities in an elastic medium. With a view to obtain detailed information about signals scattered from complex defects various analytical and numerical techniques have emerged. In this article we present a combined finite elements and eigenfunction expansion technique for solving scattering problems involving multiple scattering as well as complex geometries. Numerical results obtained by this method are compared with recent experimental results. In the following we first summarize the theoretical treatment. Then we present the finite elements and eigenfunction expansion technique (FEEET). Numerical and experimental results are presented next. Although the results presented here are for homogeneous materials, the method can readily be extended to composite materials.

9 citations

Journal ArticleDOI
TL;DR: In this paper, a model study of the interaction of the A0 and S0 guided wave modes with the joint material is presented, and it is shown that as the frequency increases the coefficient of reflection shows resonant peaks at the cutoff frequencies of higher guided modes.
Abstract: Reflection of guided waves by a thin region of bonding material at the interface between two composite plates has been investigated in this paper. The study is motivated by the need to develop a quantitative ultrasonic technique to characterize properties of joints between two plates, which may be laminated and anisotropic. Although there have been some recent studies that have examined the reflection and transmission of surface waves at the interface between two plates, they consider the two plates to be semi‐infinite in thickness. Thus the mode conversion of waves into higher guided modes of the plates are not taken into account. In this paper, a model study of the interaction of the A0 and S0 guided wave modes with the joint material is presented. It is shown that as the frequency increases the coefficient of reflection shows resonant peaks at the cutoff frequencies of higher guided modes. These peaks become increasingly pronounced as the thickness of the joint increases. Another interesting feature is...

9 citations


Cited by
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Book ChapterDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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