The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Fuhgwo Yuan - One of the best experts on this subject based on the ideXlab platform.
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iwshm 2017 damage scattered wave extraction in an integral stiffened Isotropic Plate a baseline subtraction free approach
Structural Health Monitoring-an International Journal, 2018Co-Authors: Patrick E Leser, William P Leser, Fuhgwo YuanAbstract:Ultrasonic guided waves enable long-distance inspection of structures for health monitoring purposes. However, this capability is diminished when applied to complex structures where damage-scattere...
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a semi analytical approach for sh guided wave mode conversion from evanescent into propagating
Ultrasonics, 2018Co-Authors: Xiang Yan, Fuhgwo YuanAbstract:Abstract Conversion of evanescent shear horizontal (SH) guided waves into propagating is presented in this paper. The conversion is exemplified by a time-harmonic SH evanescent displacement prescribed on a narrow aperture at an edge of a semi-infinite Isotropic Plate. The conversion efficiency in terms of the amplitude of the propagating SH mode converted from evanescent can be expressed in a very simple compact form. The magnitude of the conversion efficiency can be quantified through a derived semi-analytical form based on the complex reciprocity theorem in conjunction with a two-dimensional (2-D) finite element analysis (FEA). Through power conversion analysis, it can be shown that the power flow generated into the Plate due to evanescent incident is complex valued. It is theoretically proved that the real part of the complex power flow is associated with the propagating SH modes, while the imaginary part is confined due to the evanescent modes at the Plate edge. The conversion efficiency and converted modes are dependent on the geometric configuration of the aperture as well as the selection of the excitation frequency.
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transient wave propagation of Isotropic Plates using a higher order Plate theory
International Journal of Solids and Structures, 2005Co-Authors: S Yang, Fuhgwo YuanAbstract:Abstract Transient wave propagation of Isotropic thin Plates using a higher-order Plate theory is presented in this paper. The aim of this investigation is to assess the applicability of the higher-order Plate theory in describing wave behavior of Isotropic Plates at higher frequencies. Both extensional and flexural waves are considered. A complete discussion of dispersion of Isotropic Plates is first investigated. All the wave modes and wave behavior for each mode in the low and high-frequency ranges are provided in detail. Using the dispersion relation and integral transforms, exact integral solutions for an Isotropic Plate subjected to pure impulse load and a number of wave excitations based on the higher-order theory are obtained and asymptotic solutions which highlight the physics of waves are also presented. The axisymmetric three-dimensional analytical solutions of linear wave equations are also presented for comparison. Results show that the higher-order theory can predict the wave behavior closely with exact linear wave solutions at higher frequencies.
Salvatore Salamone - One of the best experts on this subject based on the ideXlab platform.
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a guided ultrasonic imaging approach in Isotropic Plate structures using edge reflections
Proceedings of SPIE, 2016Co-Authors: Arvin Ebrahimkhanlou, Brennan Dubuc, Salvatore SalamoneAbstract:This paper presents an imaging technique to locate damage in Plate-like structures by permanently attached piezoelectric transducers (PZT) capable to generate and receive guided ultrasonic waves. The technique is based on a model capable of predicting envelope of scattered waves. Correlations between the estimated scattered waves and experimental data are used for image reconstruction. The approach is validated on an aluminum Plate and results are compared with two common imaging algorithms, that is, Delay and Sum (DS) and Minimum Variance (MV). Damage is simulated by placing two magnets on sides of the Plate. It is shown that the inclusion of Lamb wave reflections improves the localization accuracy while making use of fewer number of sensors possible.
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Adaptive multisensor data fusion for acoustic emission source localization in noisy environment
Structural Health Monitoring: An International Journal, 2012Co-Authors: Ehsan Dehghan Niri, Alireza Farhidzadeh, Salvatore SalamoneAbstract:This article proposes an adaptive multisensor fusion algorithm for acoustic emission source location in Isotropic Plate-like structures in noisy environments. Overall, the approach consists of the ...
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temperature effects in ultrasonic lamb wave structural health monitoring systems
Journal of the Acoustical Society of America, 2008Co-Authors: Francesco Lanza Di Scalea, Salvatore SalamoneAbstract:There is a need to better understand the effect of temperature changes on the response of ultrasonic guided-wave pitch-catch systems used for structural health monitoring. A model is proposed to account for all relevant temperature-dependent parameters of a pitch-catch system on an Isotropic Plate, including the actuator-Plate and Plate-sensor interactions through shear-lag behavior, the piezoelectric and dielectric permittivity properties of the transducers, and the Lamb wave dispersion properties of the substrate Plate. The model is used to predict the S0 and A0 response spectra in aluminum Plates for the temperature range of −40–+60°C, which accounts for normal aircraft operations. The transducers examined are monolithic PZT-5A [PZT denotes Pb(Zr–Ti)O3] patches and flexible macrofiber composite type P1 patches. The study shows substantial changes in Lamb wave amplitude response caused solely by temperature excursions. It is also shown that, for the transducers considered, the response amplitude changes...
J N Sharma - One of the best experts on this subject based on the ideXlab platform.
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rayleigh lamb waves in magneto thermoelastic homogeneous Isotropic Plate
International Journal of Engineering Science, 2004Co-Authors: J N SharmaAbstract:The propagation of magnetic-thermoelastic plane wave in an initially unstressed, homogeneous Isotropic, conducting Plate under uniform static magnetic field has been investigated. The generalized theory of thermoelasticity is employed, by assuming electrical behaviour as quasi-static and the mechanical behaviour as dynamic, to study the problem. The secular equations for both symmetric and skew-symmetric waves have been obtained. The magneto-elastic shear horizontal (SH) mode of wave propagation gets decoupled from rest of the motion and it is not influenced by thermal variations and thermal relaxation times. At short wavelength limits, the secular equations for symmetric and skew-symmetric modes reduce to Rayleigh surface wave frequency equation, because a finite thickness Plate in such a situation behaves like a semi-infinite medium. Thin Plate results are also deduced at the end. Dispersion curves are represented graphically for various modes of wave propagation in different theories of thermoelasticity. The amplitudes of displacement, perturbed magnetic field and temperature change are also obtained analytically and computed numerically. The result in case of elastokinetics, magneto-elasticity and coupled magneto-elasticity has also been deduced as special cases at appropriate stages of this work.
Roberta Sburlati - One of the best experts on this subject based on the ideXlab platform.
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stress concentration factor due to a functionally graded ring around a hole in an Isotropic Plate
International Journal of Solids and Structures, 2013Co-Authors: Roberta SburlatiAbstract:Abstract The aim of this work is to present an analytical solution to reduce the stress concentration factor (SCF) around a circular hole in an Isotropic homogeneous Plate subjected to far-field uniaxial loading. In this paper the elastic response of an inhomogeneous annular ring made of functionally graded material (FGM), inserted around a hole of a homogeneous Plate, is studied. By assuming that Young’s modulus varies in the radial direction with power law and that Poisson’s ratio is constant, the governing differential equations for plane stress conditions are obtained. Using stress function a general solution in explicit closed form is presented and the SCF investigated to highlight the inhomogeneity effects. Furthermore, the explicit solution for an inner homogeneous ring, with different properties with respect to those of the Plate, is explicitly obtained and numerical results are compared between homogeneous ring and FGM ring.
M J S Lowe - One of the best experts on this subject based on the ideXlab platform.
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scattering of the fundamental shear horizontal guided wave by a part thickness crack in an Isotropic Plate
Journal of the Acoustical Society of America, 2008Co-Authors: Prabhu Rajagopal, M J S LoweAbstract:The interaction of the fundamental shear horizontal (SH0) guided mode with part-thickness cracks in an Isotropic Plate is studied as an extension within the context and general framework of previous work [“Short range scattering of the fundamental shear horizontal guided wave mode normally incident at a through thickness crack in an Isotropic Plate,” J. Acoust Soc. Am. 122, 1527–1538 (2007); “Angular influence on scattering when the fundamental shear horizontal guided wave mode is incident at a through-thickness crack in an Isotropic Plate,” J. Acoust. Soc. Am. 124, 2021–2030 (2008)] by the authors with through-cracks. The symmetric incidence case where the principal direction of the incident beam bisects the crack face at 90° is studied using finite element simulations validated by experiments and analysis, and conclusions are inferred for general incidence angles using insights obtained with the through-thickness studies. The influence of the crack length and the monitoring distance on the specular refl...
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angular influence on the scattering of fundamental shear horizontal guided waves by a through thickness crack in an Isotropic Plate
Journal of the Acoustical Society of America, 2008Co-Authors: Prabhu Rajagopal, M J S LoweAbstract:The angular influence on the scattering of cylindrical-crested waves of the fundamental shear horizontal (SH0) guided mode by through-thickness cracks in an Isotropic Plate is studied in the context of array imaging using ultrasonic guided waves. Finite element simulations are used to obtain trends which are subject to analytical study and experimental confirmation. The influence of the incidence angle on reflection behavior is first studied in terms of two complementary cases, that of normal incidence and that of specular reflection at various oblique incidence angles. The normal incidence study suggests that for a given incidence angle, the peak reflection is concentrated around the specular direction, while the oblique incidence studies show that maximum specular reflection occurs in the case of normal incidence. The variation of diffraction with both the angle of incidence and that of monitoring is then taken up and this shows that when the first diffraction from the crack edges can be separated, its angular dependence can be obtained from literature on similar bulk elastic wave scattering problems.
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short range scattering of the fundamental shear horizontal guided wave mode normally incident at a through thickness crack in an Isotropic Plate
Journal of the Acoustical Society of America, 2007Co-Authors: Prabhu Rajagopal, M J S LoweAbstract:Interaction of the fundamental shear horizontal mode with through-thickness cracks in an Isotropic Plate is studied in the context of low frequency array imaging for ultrasonic guided wave nondestructive evaluation with improved resolution. Circular wave fronts are used and the symmetric case where a line from the wave source bisects the crack face normally is considered. Finite element simulations are employed to obtain trends subject to analytical and experimental validation. The influence of the crack length and of the location of source and measurement positions on the specular reflection from the crack face is first examined. These studies show that low frequency short range scattering is strongly affected by diffraction phenomena, leading to focusing of energy by the crack in the backscatter direction. Study of the diffraction from the crack edges reveals contributions due to a direct diffraction at the edges and multiple reverberations across the crack length. A simple diffraction model is shown to adequately represent cracks up to moderate lengths, providing an easy means of estimating the far field of the waves. The presence of multiple diffraction components is quantitatively established and surface waves on the crack face are identified as equivalent to low frequency symmetric modes of rectangular ridge waveguides.
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short range scattering of the fundamental shear horizontal guided wave mode normally incident at a through thickness crack in an Isotropic Plate
Journal of the Acoustical Society of America, 2007Co-Authors: Prabhu Rajagopal, M J S LoweAbstract:Interaction of the fundamental shear horizontal mode with through-thickness cracks in an Isotropic Plate is studied in the context of low frequency array imaging for ultrasonic guided wave nondestructive evaluation with improved resolution. Circular wave fronts are used and the symmetric case where a line from the wave source bisects the crack face normally is considered. Finite element simulations are employed to obtain trends subject to analytical and experimental validation. The influence of the crack length and of the location of source and measurement positions on the specular reflection from the crack face is first examined. These studies show that low frequency short range scattering is strongly affected by diffraction phenomena, leading to focusing of energy by the crack in the backscatter direction. Study of the diffraction from the crack edges reveals contributions due to a direct diffraction at the edges and multiple reverberations across the crack length. A simple diffraction model is shown to...
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scattering of the fundamental shear horizontal guided wave mode incident at an arbitrary angle on finite slits in an Isotropic Plate
REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION, 2007Co-Authors: Prabhu Rajagopal, M J S LoweAbstract:This paper considers the interaction of the fundamental shear horizontal (SH0) mode with through‐slits in an Isotropic Plate, in the context of higher resolution ultrasonic guided wave NDE. The background to this research and the case of normal incidence of the SH0 mode on through‐cracks were presented at QNDE, 2005. Here the results of the previous study are first validated with some preliminary experiments and further comparison with literature. Insights from these are then used to understand the more complex multi‐parameter case of scattering at an arbitrary angle of incidence. Finally the findings are used to draw implications for some key questions involving the development of array imaging procedures.
