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  • Articles  (17)
  • Ultrasonics  (17)
  • 1990-1994  (7)
  • 1985-1989  (10)
  • 1960-1964
  • 1950-1954
  • Electrical Engineering, Measurement and Control Technology  (17)
  • 1
    Electronic Resource
    Electronic Resource
    Backscattered microstructural noise in ultrasonic toneburst inspections (1994)
    Springer
    Journal of nondestructive evaluation 13 (1994), S. 111-136 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; backscattering ; noise ; backscatter coefficient ; figure-of-merit ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A model is presented which relates the absolute backscattered noise level observed in an ultrasonic immersion inspection to details of the measurement system and properties of the metal specimen under study. The model assumes that the backscattered noise signal observed for a given transducer position is an incoherent superposition of echoes from many grains. The model applies to normal-incidence, pulse-echo inspections of weakly-scattering materials using toneburst pulses from either a planar or focused transducer. The model can be used in two distinct ways. Measured noise echoes can be analyzed to deduce a “Figure-of-Merit” (FOM) which is a property of the specimen alone, and which parameterizes the contribution of the microstructure to the observed noise. If the FOM is known, the model can be used to predict the absolute noise levels that would be observed under various inspection scenarios. Tests of the model are reported, using both synthetic noise echoes, and measured noise echoes from metal specimens having simple and complicated microstructures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00728250
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  • 2
    Electronic Resource
    Electronic Resource
    Self-calibrating ultrasonic technique for crack depth measurement (1992)
    Springer
    Journal of nondestructive evaluation 11 (1992), S. 103-108 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; surface breaking cracks ; self-calibrating ; crack depths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A configuration of transducers together with a self-calibrating measurement technique is proposed to investigate the reflection and transmission of surface waves by a surface-breaking or near surface defect. By means of this technique, the ratio of the reflection and transmission coefficients (R/T and/orT/R) can be obtained in a reliable and accurate manner. The reflection and transmission of surface waves for oblique incidence on a surface breaking crack is investigated in detail. Information onT/R for the latter case can be used to determine the depth of the crack. The experimental measurements ofT/R show excellent agreement with theoretical results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568293
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  • 3
    Electronic Resource
    Electronic Resource
    Reflection of ultrasonic waves from imperfect interfaces: A combined boundary element method and independent scattering model approach (1992)
    Springer
    Journal of nondestructive evaluation 11 (1992), S. 141-149 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; imperfect interfaces ; quasi-static ; reflection coefficients ; spring constants ; independent scattering ; boundary element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A numerical technique for obtaining interface reflection coefficients for imperfect bonds between similar materials for a wide range of distributed defects is developed. A numerical boundary element method is utilized to find the far-field scattering amplitudes of a single defect for a normally incident plane wave. Then, the normal incidence reflection coefficient for a planar distribution of such defects is obtained from the independent scattering model. As a validation, the reflection coefficients are compared to the quasi-static model results where the latter are available. This establishes the basis for one application of the new model, the determination of spring constants which are not available. Other applications of the model, including studies of the response at frequencies beyond the quasi-static limit, the ratio of longitudinal to transverse wave reflectivities, and the effects of selected multiple scattering are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566405
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  • 4
    Electronic Resource
    Electronic Resource
    Utilization of prior flaw information in ultrasonic NDE: An analysis of flaw scattering amplitude as a random variable (1992)
    Springer
    Journal of nondestructive evaluation 11 (1992), S. 57-67 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; digital signal processing ; flaw scattering amplitude ; prior information ; random variable analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Probabilistic approaches to flaw detection, classification, or characterization often assume prior knowledge of the flaw distribution. It is implicit that there is a scattering amplitude distribution associated with the flaw distribution. In a number of previously published probabilistic analyses, it has been assumed that scattering amplitude is an uncorrelated, Gaussian random variable with zero mean and known variance. In the work reported here, these assumptions are evaluated for the case of a lognormal distribution of spherical flaws. The correlation, mean, variance, and nature of the scattering amplitude distribution are considered as a function of frequency and as a function of the breadth of the assumed flaw distribution. It is shown for the assumed flaw distributions that scattering amplitude is not uncorrelated and does not have zero mean. It is shown that errors in estimating the flaw distribution variance affect both the scattering amplitude mean and variance. Using both analytical and numerical procedures, the scattering amplitude distribution is shown to be lognormal at long wavelength for a lognormal distribution of spherical scatterers. At high frequency, the distribution is shown to have a bimodal character.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568289
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  • 5
    Electronic Resource
    Electronic Resource
    Far-field radiation of a vibrating point source in anisotropic media (1991)
    Springer
    Journal of nondestructive evaluation 10 (1991), S. 71-78 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; far-field radiation ; anisotropic media ; directivity pattern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In this paper, Lamb's technique,(1) which was used to study acoustic radiation due to an external force acting in an infinite isotropic solid or over the surface of an isotropic solid, has been extended to the case of general anisotropic media. The far-field radiation is numerically calculated for a vibrating point source in an infinite anisotropic solid or on the free surface of a semi-infinite anisotropic solid. The directivity patterns of a point source are obtained for the three different elastic modes, and a brief discussion of the main features of the numerical results is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568102
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  • 6
    Electronic Resource
    Electronic Resource
    Computer simulation of ultrasonics and its applications (1990)
    Springer
    Journal of nondestructive evaluation 9 (1990), S. 81-99 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; visualization ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Numerical calculations have been carried out for about 20 years, and the results are demonstrated graphically by vector or lattice representations. These results are now being used mainly for clarifying the mechanisms of ultrasonic interaction with material and defects and checking and improving the experimental results. Parts of this paper review results, many involving cracktip diffraction in various geometries, which have been published mainly in conference proceedings and have not appeared in journals. Other parts, dealing with focused fields, focal lenses, and radiation in an anisotropic medium are new, and have not appeared even as conference papers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566386
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  • 7
    Electronic Resource
    Electronic Resource
    Application of the boundary element method to elastic wave scattering by irregular defects (1990)
    Springer
    Journal of nondestructive evaluation 9 (1990), S. 113-127 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; modeling ; scattering ; boundary element method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A time-harmonic boundary element formulation for elastic wave scattering in 3D is adapted to ultrasonic NDE. Defect classes addressed are volumetric voids and inclusions, and crack-like elliptical voids. For axisymmetric flaws, comparisons are made with method of optimal truncation (MOOT) and transition-matrix calculations. Comparison to experiment is made for more general shapes. For crack-like voids, comparisons are made with the Kirchhoff, geometric theory of diffraction (GTD), and quasistatic asymptotic approximations. The efficiency and usefulness of the boundary element method (BEM) in finding the bounds of applicability of these approximate theories are demonstrated. An example of a flaw characterization technique based on intermediate frequency scattering data simulated by BEM is given. The ability of BEM to handle nonplanar incident fields, as described by a transducer beam model, is shown. Other computational and modeling efficiencies of the BEM are noted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566388
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  • 8
    Electronic Resource
    Electronic Resource
    A numerical integration Green's function model for ultrasonic field profiles in mildly anisotropic media (1989)
    Springer
    Journal of nondestructive evaluation 8 (1989), S. 165-179 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; Green's function ; anisotropic media ; field profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A numerical integration technique utilizing a point source Green's function is introduced to analyze the wave behavior in transversely isotropic-type anisotropic media allowing us to make fast and accurate computations of the acoustic field. The centrifugally cast stainless steel (CCSS) used in nuclear power plants is chosen as a sample medium because of its columnar grain character leading to material anisotropy. A representative number of field profiles are computed and plotted to illustrate the quasi-longitudinal, quasi-transverse, and horizontally-polarized shear wave propagation in a transversely-isotropic medium. Phenomena such as beam skewing, beam splitting, beam focusing, unsymmetrical beams, and other anisotropic effects, some of which are already known from earlier experimental observations, emerge as a computational result of the introduced technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570885
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  • 9
    Electronic Resource
    Electronic Resource
    Interfacial spring model for ultrasonic interactions with imperfect interfaces: Theory of oblique incidence and application to diffusion-bonded butt joints (1988)
    Springer
    Journal of nondestructive evaluation 7 (1988), S. 131-152 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; diffusion bonds ; oblique incidence ; spring model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The quasi-static distributed spring model is used to derive the ultrasonic reflectivity of an imperfectly-bonded interface as a function of frequency and angle of incidence. The results are then incorporated in a model for the corner reflection from a diffusion-bonded joint between two abutting plates, the corner being defined by the bond plane and the common lower surface plane of the plates. An immersion-inspection geometry is assumed, and seven categories of corner reflections are identified and examined in detail. These fall into two classes: those having parallel incident and exiting rays in water (φ′=φ), and those having nonparallel water rays (φ′ ≠ φ). The φ′ = φ categories are suitable for single probe (pulse-echo) inspections of the joint. Based on the amplitude of the outgoing corner-reflected signal, two φ = φ′ geometries appear promising. These employ, respectively, a corner reflection involving only longitudinal waves with the interface illuminated at near-grazing incidence (LLL), and a corner reflection involving only transverse waves with the interface illuminated at near 45° incidence (TTT). In addition, two practical φ′ ≠ φ geometries are indicated; these both involve mode conversion upon reflection from the interface, with the incident or outgoing longitudinal wave traveling nearly parallel to the interface. Model predictions for LLL and TTT reflections are compared to measurements on diffusion-bonded Inconel specimens, and techniques for applying the model results to more complicated bond geometries are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00565998
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrasonic characterization of tubing pinch welds (1988)
    Springer
    Journal of nondestructive evaluation 7 (1988), S. 217-225 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; pinch welds ; solid-state bonds ; grain scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Spatially-focused, high-frequency ultrasonic pulses have been used in the evaluation of the quality of stainless steel tubing pinch welds. Experimentally, echoes from the bond plane were generally too weak to observe, except in bond planes with macrocracking. Correlations were therefore sought between bond quality and the amplitude and spectral features of the back-surface echo that has passed through the bond plane twice. Linear scans of the back-surface echo parallel and perpendicular to the tubing axis were made on pinch welds of four classes of bond quality. Trends, with scatter, were observed between the ultrasonic parameters and bond quality. These experimental results were interpreted using the Stanke-Kino theory of ultrasonic attenuation due to grain scattering to relate the microstructural changes caused by the pinch-weld process to the observed ultrasonic signals. The results illustrate the importance of process-related changes in near-bond microstructure in attempts to nondestructively determine bond strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566004
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  • 11
    Electronic Resource
    Electronic Resource
    Ultrasonic evaluation of solid-state welds (1988)
    Springer
    Journal of nondestructive evaluation 7 (1988), S. 227-235 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; solid-state welding ; pattern recognition ; feature extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Ultrasonic techniques for evaluating the quality of solid-state weld interfaces have been investigated over the past several years. Promising results have been obtained on a variety of solid-state welds by extracting features from the ultrasonic wave forms and applying pattern recognition algorithms to separate acceptable from unacceptable welds. The general conclusion is that the ultrasonic features most sensitive to interfacial bonding are those dependent on high frequencies. However, no single feature has been discovered that is adequate to yield separation of good vs. poor welds, since the microstructural response is also frequency dependent. Given the increase in sensitivity and resolution with high-frequency ultrasonic evaluation, selected specimens have been examined with acoustic microscopy. These specially prepared samples were inspected with focused transducers at frequencies in the 35–75 MHz range. The reflections observed indicated bond quality to vary in discrete regions with good and poor regions distributed across the diameter. Corresponding variations in the degree of bonding have been observed on the fracture surfaces of mechanically-tested specimens. The development of both low- and high-frequency acoustic microscopy has led to the possibility of sensing and imaging subtle changes in the reflection coefficient of the bond line. These acoustic images will improve our understanding of the mechanisms involved in evaluating solid-state bonds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566005
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  • 12
    Electronic Resource
    Electronic Resource
    A self-calibrating technique for the ultrasonic discrimination of solid-state welds (1988)
    Springer
    Journal of nondestructive evaluation 7 (1988), S. 191-197 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; solid-state welds ; calibration ; discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper presents the description and application of a self-calibrating technique for ultrasonic weld discrimination. A broad-band ultrasonic transducer is bonded to one side of the component containing the weld. The transducer transmits and receives short pulses in the pulse-echo mode. The received short pulses are processed to provide data on weld quality. The technique is self-calibrating in the sense that the capture of two waveforms in a single measurement provides enough information to remove the transducer transfer function and transducer bond losses. A key feature of the technique is the elimination of the deleterious effects of ultrasonic bond variability, which was found to be the major limitation for the materials investigated in this study. Another feature is the requirement of access to one side of the weld only. The technique is applied to solid-state welds involving two types of steel, i.e., martensitic and austenitic steel. For the martensitic steels, substantial improvement over previous studies was seen and first- and fourth-class welds could be discriminated. On the other hand, the austenitic steel welds are examples which demonstrate the need for still further improvements, since the discrimination between first- and fourth-class welds was only marginal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566002
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  • 13
    Electronic Resource
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    Laser excitation through fiber optics for NDE (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 57-64 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; fiber optics ; lasers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper describes experiments designed to generate acoustic waves by using a laser pulse, transmitted through fiber optics, to thermally shock the surface of a steel specimen. The purpose of this effort was to explore the noncontacting generation of Rayleigh surface waves appropriate to the interrogation of structures for the detection of subcritical defects, with the ultimate goal of developing an efficient laser-based nondestructive evaluation technique utilizing flexible fiber optics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566697
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  • 14
    Electronic Resource
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    Separation and characterization of stress levels and texture in metal sheet and plate. II. Rolled copper sheet experiment (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 33-45 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; texture ; metals ; EMATs ; nondestructive evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In this paper, we compared elastic shear moduli determined by EMAT techniques to x-ray pole figure measurements for three lots of rolled copper sheet. All moduli (C′44,C′55,C′66) decreased with rolling reduction to more than −10% for a 90% rolling reduction and the difference betweenC 44 andC 55 increased with developing in-plane anisotropy as predicted in Part 1. Pole figures of (111) and (200) planes revealed various initial textures for the starting annealed plates, and (111) pole rotation toward a single well-defined preferred orientation at large rolling reductions. Stress relief annealing of a heavily cold rolled plate produced no significant changes in elastic moduli while hardness decreased, thus indicating that textural changes were responsible for the observed moduli changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566695
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  • 15
    Electronic Resource
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    Fiber optic sensing for ultrasonic NDE (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 135-146 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; fiber optics ; lasers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An innovative approach to nondestructive evaluation (NDE) using noncontacting optical sensors has demonstrated. In this effort a single mode optical fiber interferometer (OFI) was used to sense the presence and form of Rayleigh waves traveling along the surface of a steel test bar at a velocity of nearly 3mm/µs. Acousto-optic time-domain data was successfully used to detect the presence and locate the position of a test “flaw” (a machined slot) in the bar, and spectrum analysis was used to estimate its geometry and size. This approach has many potential applications in the ultrasonic evaluation of real flaws in structures with complex geometries. Coupled with the authors' earlier work demonstrating the feasibility of generating acoustic waves in metals using laser light pulses transmitted through the fiber optic probes, this latest achievement points to the development of a fully noncontacting, fiber optic based thermal-acousto-photonic (TAP) NDE system, with potential applications to the reliability testing of many important structures where composition, scale, geometry, or restricted access preclude the use of conventional NDE techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568009
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  • 16
    Electronic Resource
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    Nondestructive detection of flaws in material using transducer arrays (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 47-55 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; transducer array ; flaw detection ; signal processing ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In this paper, we describe a system which uses array filters for processing the recordings of an array of transducers for the purpose of locating possible flaws in the material being tested nondestructively. When applied, in order to focus the array outputs at a point inside the material, these filters are able to attenuate, very effectively, interfering residual energy scattered from adjacent flaws, as well as random noise. If there is a flaw at the point of focus, the summed output of the filters will have a large signal at a delay time corresponding to the total travel time for this point; otherwise the output will consist mainly of residual random noise. Thus, the location of flaws or even microflaws in material may be achieved by simple threshold detection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566696
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  • 17
    Electronic Resource
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    Diffraction of elastic waves by defects in plates: Calculated arrival strengths for point force and thermoelastic sources of ultrasound (1986)
    Springer
    Journal of nondestructive evaluation 5 (1986), S. 145-156 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasonics ; elastic waves ; diffraction ; defects ; time-of-flight technique ; thermoelastic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract This paper applies geometrical ray theory to the calculation of the surface displacements generated by point force and thermoelastic sources of ultrasound in plates containing planar defects. The calculation includes direct wave arrivals, waves undergoing back-wall reflection with or without mode conversion, and waves diffracted by the crack-tip. Ultrasonic B-scan data are also simulated so that comparison can be made with experimental data. It is shown that the thermoelastic source, which can be generated by a pulsed laser, is particularly well suited to defect detection by the ultrasonic time-of-flight technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570623
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