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  • Articles  (8)
  • ultrasonics  (8)
  • 1995-1999
  • 1980-1984  (8)
  • 1925-1929
  • 1984  (4)
  • 1980  (4)
  • Mathematics  (8)
  • Sociology
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  • Articles  (8)
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Keywords
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Years
  • 1995-1999
  • 1980-1984  (8)
  • 1925-1929
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Ultrasonic scattering from imperfect interfaces: A quasi-static model (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 177-196 
    Details
    ISSN: 1573-4862
    Keywords: Interfaces ; ultrasonics ; partial contact ; quasi-static
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A quasi-static model for the ultrasonic transmission and reflection at imperfect interfaces is developed. The interface is represented by a distributed spring, determined by the change in static compliance of the medium with respect to one with a perfect interface, and a distributed mass, representing excess mass at the interface. Comparison of the model predictions to exact solutions for two simple cases illustrates its accuracy at low frequencies. The spring stiffnesses can be derived from existing solutions for the elastic displacement of materials containing cracks and inclusions under static load. Results for a variety of cases are reviewed. Applications of the model to study the characteristics of partially contacting surfaces in several problem areas of current interest are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566223
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Methods for determining the depth of near-surface defects (1980)
    Springer
    Journal of nondestructive evaluation 1 (1980), S. 21-36 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; surface defects ; defect depth ; deconvolution ; correlation ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In previous work by the authors,(1,6) it was demonstrated that the presence of near-surface defects could be detected reliably, even though the defect echo was contained within the near-surface echo. The algorithm consists of examining the variation in the composite (near-surface plus defect) response after it has been deconvolved from a near-surface response known to be defect-free. This paper presents two algorithms that have been developed subsequent to the work presented in ref. (6) for estimating thedepth of a near-surface defect, given that its presence has already been detected. One algorithm uses complex frequency domain techniques, and the other uses time domain analysis. Both procedures operate on the surface-plus-defect signal, using reference signals containing surface-only and defect-only responses. The defect signal is extracted from the composite signal. Defect depth is then computed from the time difference between the centers of the front-surface and extracted defect responses. A mean absolute depth error of 0.015 in. was obtained by applying the algorithms to experimental data containing depths from 0.020 to 0.130 in. below the near-surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566229
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Accept/reject decisions and failure prediction for structural ceramics: Application to failure from voids (1980)
    Springer
    Journal of nondestructive evaluation 1 (1980), S. 37-52 
    Details
    ISSN: 1573-4862
    Keywords: failure prediction ; accept/reject decisions ; ceramic materials ; ultrasonics ; fracture ; probabilistic model ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A general probabilistic method for reaching accept/reject decisions and failure prediction based on nondestructive evaluation procedures is described. The method is illustrated for ceramic materials that fail by the activation of microcracks located at void surfaces. The inspection procedure used for the analysis is the long wavelength ultrasonic method. The analysis indicates influences on the decision level and on the false-reject probability of variations in the signal-to-noise ratio and in the preexistent void population. The ultrasonic inspection is shown to exert a relatively minor influence on the false-reject probability, even for low signal-to-noise ratios, low stresses, and a widely dispersed void population, because of the intrinsic variability of the selected failure process. More encouraging results concerning the utility of NDE are anticipated to apply to other failure mechanisms in ceramics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566230
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  • 4
    Electronic Resource
    Electronic Resource
    Elastic wave diffraction by elliptical cracks: Theory and experiment (1980)
    Springer
    Journal of nondestructive evaluation 1 (1980), S. 87-99 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; diffraction ; cracks ; titanium ; spectrum analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Analytical solutions to the diffraction of elastic waves by elliptical cracks in titanium are compared with experimental results. The analysis is based on physical elastodynamic theory and is valid forka≫1 and in the far field. A digitized ultrasonic spectrum analysis system is used to measure the frequency components of broadband waves diffracted from elliptical cracks with aspect ratios (ratio of major to minor axes) ranging from 1 to 8. The amplitude spectra show good agreement between experiment and theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566117
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  • 5
    Electronic Resource
    Electronic Resource
    Separation and characterization of stress levels and texture in metal sheet and plate: I. Principles and preliminary experiment (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 157-163 
    Details
    ISSN: 1573-4862
    Keywords: Residual Stress ; ultrasonics ; metals ; EMATs ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An approach is proposed for obtaining separate measures of stress anisotropy and texture in metal sheet or plate. The approach is based on the propagation characteristics ofSH n modes of ultrasonic waves. Experimental work has established that differences betweenSH 0 modes with orthogonal directions of propagation provide a measure of stress anisotropy that is insensitive to texture, with the restriction that the pseudosymmetry of the polycrystalline matrix of the sheet or plate is orthorhombic or higher. In the present work, it is argued that the differences between elastic constants associated with orthogonal directions of propagation of higher order modes should provide a meaningful measure of texture. The only requirement is that the texture be sufficiently well developed so that the following inequality is obeyed: ∣C′44−C′55∣〉0.002 $$\bar C$$ with $$\bar C$$ =1/2 (C′44+C′55). HereC′44 andC′55 are the effective shear moduli for planes normal to the sheet or plate surface and at right angles to each other. They are measurable by observing the differences between the phase velocities of theSH 0 and theSH n〉0 modes in the principal directions. By using Electromagnetic Acoustic Transducers (EMATs), the phase velocities can be deduced from the frequencies at which an SH mode of fixed wavelength is optimally excited. This approach has the advantage of being independent of specimen geometry and dimensions other than thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566221
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  • 6
    Electronic Resource
    Electronic Resource
    Acousto-optic method for nondestructive testing (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 43-50 
    Details
    ISSN: 1573-4862
    Keywords: Acousto-optic ; light diffraction ; ultrasonics ; phase measurements ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract An alternative method for nondestructive testing based on light diffraction by ultrasonic waves is presented. It enables us to make more accurate measurements of intensity and phase of reflected waves, and therefore detailed information about the reflecting system can be obtained. Applications are numerous but special attention is payed to examination of the quality of coupling systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711100
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of focusing and refraction on Gaussian ultrasonic beams (1984)
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 107-123 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; transducers ; focusing ; refractior ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A scalar theory of the propagation of Gaussian ultrasonic beams through lenses and interfaces is presented. For radiation into a fluid, the Fresnel approximation is employed to derive the laws of propagation of Guassian beams (previously employed in the analysis of coherent optical systems). These are then generalized to situations commonly found in nondestructive evaluation by treating the effects of propagation through lenses and through curved interfaces at oblique incidence. A numerical example illustrates the ease with which insight into diffraction phenomena for complex geometries can be gained by this approach. The limitations imposed on the theory by aberrations and the scalar assumption are discussed, and the relationship of the Gaussian theory to the radiation of piston transducers is explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566401
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  • 8
    Electronic Resource
    Electronic Resource
    Fatigue lifetime prediction with the aid of SAW NDE (1980)
    Springer
    Journal of nondestructive evaluation 1 (1980), S. 123-136 
    Details
    ISSN: 1573-4862
    Keywords: fatigue life ; acoustic surface waves ; NDE ; ultrasonics ; cracks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The present studies concentrated on predicting the remaining fatigue life for single fatigue cracks in the Paris regime of macrocrack propagation. Acoustic surface waves were used to interrogate the crack during cyclic fatigue. The inversion of the obtained scattering data provided crack depth and crack length as a function of the number of cycles applied in tension-tension fatigue. Auxiliary experiments were conducted to study the acoustic response of the crack to tensile and compressive loads, thought to open and close the crack. The technique may allow for new insights into the physics of the “crack closure” effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566120
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