ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (10)
  • Other Sources
  • ultrasonics  (10)
  • 1985-1989  (3)
  • 1980-1984  (7)
  • 1965-1969
  • Mathematics  (10)
  • Education
Collection
  • Articles  (10)
  • Other Sources
Source
Keywords
Publisher
Years
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Ultrasonic reflection by a planar distribution of cracks (1988)
    Springer
    Journal of nondestructive evaluation 7 (1988), S. 123-129 
    Details
    ISSN: 1573-4862
    Keywords: Diffusion bonds ; reflection ; ultrasonics ; cracks ; stress-intensity factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Ultrasonic wave reflection and transmission by planar crack distributions is considered. General expressions for the reflection and transmission coefficients are derived for incident longitudinal and transverse time harmonic plane waves. For low frequencies, closed-form algebraic expressions are given in terms of the geometrical parameters, the material constants, and the incident wavefield. The results have been extended to statistical distributions, and reflection coefficients for equivalent statistical and deterministic distributions of penny-shaped cracks are compared. It is also shown that the Mode-I stress-intensity factor for a distribution of equal-sized cracks can be directly related to reflection data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00565997
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Interior imaging using spatial frequency sampling (1981)
    Springer
    Journal of nondestructive evaluation 2 (1981), S. 203-207 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; synthetic aperture ; spatial frequency ; interior imaging ; acoustic microscopy ; defect detection ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A new acoustic synthetic aperture geometry is demonstrated in which the image field is sampled in the spatial frequency domain. This means the sampled field is recorded in a particularly convenient form for presentation to the back propagation algorithms used to reconstruct the field at the object plane. The method has applications in interior visualization. It is difficult to image the interior of solid objects using lens based imaging systems because a different lens geometry must be used for each distinct object material. The system presented here overcomes such problems since both the angular variation of the transmission coefficient at the object-water interface and the aberrations introduced by the velocity mismatch at the object surface may be readily compensated for in the back propagation routine. Experimental results are presented illustrating the detection of four half wavelength diameter defects, spaced by three wavelengths, at a depth of eight wavelengths below the surface of an aluminum block.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570732
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Ill-posed and well-posed problems in inverse elastodynamic scattering for nondestructive evaluation (1981)
    Springer
    Journal of nondestructive evaluation 2 (1981), S. 161-172 
    Details
    ISSN: 1573-4862
    Keywords: elastodynamic inverse scattering ; ultrasonics ; data reduction ; ill-posed problems ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The practical significance of ill-posedness in a data reduction problem is reviewed. Inverse elastodynamic scattering is shown to be ill-posed in general, although suitably restricted problems may be well-posed. These results underscore the need to analyze carefully the errors of data reduction problems in NDE, and to focus attention on final results of an NDE exercise, rather than on intermediate steps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570728
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Effects of sinusoidal crack-face perturbations on scattering of elastic waves (1981)
    Springer
    Journal of nondestructive evaluation 2 (1981), S. 153-159 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; scattering ; cracks ; periodic surface perturbation ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The scattering of a plane longitudinal wave from a two-dimensional crack, with a sinusoidal surface perturbation whose amplitude and wavelength are much smaller than the length of the crack, is investigated. The amplitude of the cylindrical body waves in the far field are calculated from a Kirchhoff approximation that utilizes the solution to the reflection from the sinusoidal surface profile of a semiinfinite solid. The results are compared to those for a flat crack, and conditions for significant differences of the amplitude as a function of the angle of observation are discussed. Characteristic changes in the scattered field produced by profiles with different amplitudes and periods are explained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570727
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    ORCHID—A computer simulation of the reliability of an NDE inspection system (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 23-31 
    Details
    ISSN: 1573-4862
    Keywords: NDE ; inspection systems ; reliability ; probability of detection ; computer simulation ; eddy current ; ultrasonics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract CANDU pressurized heavy water reactors contain several hundred horizontally-mounted zirconium alloy pressure tubes. Following a pressure tube failure, a pressure tube inspection system called CIGARette was rapidly designed, manufactured and put in operation. Defects called hydride blisters were found to be the cause of the failure, and were detected using a combination of eddy current and ultrasonic scans. A number of improvements were made to CIGARette during the inspection period. The ORCHID computer program models the operation of the delivery system, eddy current and ultrasonic systems by imitating the on-reactor decision-making procedure. ORCHID predicts that during the early stage of development, less than one blistered tube in three would be detected, while less than one in two would be detected in the middle development stage. However, ORCHID predicts that during the late development stage, probability of detection will be over 90%, primarily due to the inclusion of axial ultrasonic scans (a procedural modification). Rotational and axial slip could severely reduce probability of detection. Comparison of CIGARette's inspection data with ORCHID's predictions indicate that the latter are compatible with the actual inspection results, though the numbers are small and data uncertain. It should be emphasized that the CIGARette system has been essentially replaced with the much more reliable CIGAR system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566694
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Ultrasonic characteristics of graphite/epoxy composite material subjected to fatigue and impacts (1986)
    Springer
    Journal of nondestructive evaluation 5 (1986), S. 119-131 
    Details
    ISSN: 1573-4862
    Keywords: graphite/epoxy ; composites ; ultrasonics ; stress wave factor ; fatigue life ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Fiber-reinforced composites, because of their superior specific strengths and stiffnesses, are used in many aircraft components. However, in this application these composites are subjected not only to fatigue loading, but to occasionally high velocity impact due to the bird injection, hail, dust, and rain. Thus, it is important to evaluate the residual life and degradation due to combined fatigue and impact loadings. Unidirectional graphite epoxy composites (MA8276-Tiger) which are used in the aerospace industry were impacted by a free falling weight at energy levels of 0.567j, 1.134j, and 1.571j [impact energy toughness (j/cm3); 0.12, 0.24, 0.34], respectively. The subsequent changes/degradation in elastic moduli, strength, toughness, and fatigue properties were measured after different number of impacts. It was found that for all energy levels these properties vary linearly with the number of impacts. Furthermore, attenuation changes is not a good ultrasonic parameter for degradation estimation, since it does not incorporate the micro- and macrocracks beyond the impact point. However, these micro- and macrocracks have significant effect on the mechanical properties. In contrast to the attenuation, the stress wave factor, which indicates the efficiency of wave propagation along the specimen, correlates very well with degradation, and it can be used effectively to measure the residual strength after impact. Ultrasonic characteristic on specimens subjected to combined fatigue and impact were also studied. Based on these experiments, it is concluded that the loss in fatigue residual life due to impact loads may be predicted by measuring the effects of the impact load on attenuation and stress wave factor. It was found that the reduction in fatigue life is proportional to sudden changes in attenuation and stress wave factor. Damage accumulation models based on Coffin-Manson equation, was suggested for impact and combined fatigue and impact. It was found that residual properties and fatigue life can be estimated from these models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570621
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Loss of specular reflection due to nonlinear crack-face interaction (1982)
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 229-239 
    Details
    ISSN: 1573-4862
    Keywords: Crack-opening displacement ; crack closure ; ultrasonics ; Kirchoff approximation ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract The interaction between rough crack faces is modeled by nonlinear relations between the crack-face tractions and the crack-opening displacements. These relations account for crack closure and for the related resistance to crack-face sliding. The relations are used to investigate reflection and transmission of an incident pulse by an infinite flaw plane. The problem statement is reduced to a set of inhomogeneous nonlinear ordinary differential equations for the displacement discontinuities, [u] and [v], across the flaw plane. These equations have been solved numerically. The reflection and transmission of an incident pulse by a crack with interacting crack faces. Both incident longitudinal and transverse waves have been considered. The loss of specular reflection as compared to a perfect (traction-free) crack is exhibited by specific examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00565867
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Computerized evaluation of acoustic images utilizing a method of averaging (1981)
    Springer
    Journal of nondestructive evaluation 2 (1981), S. 173-188 
    Details
    ISSN: 1573-4862
    Keywords: ultrasonics ; acoustic imaging ; computer image analysis ; failure prediction ; inhomogeneous materials ; accept/reject criteria ; NDE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A computerized technique is presented which has been developed for analyzing acoustic images of an inhomogeneous material. The acoustic imaging system is briefly described with emphasis on its adaptation to billets of graphite for atmospheric reentry body use. Ultrasonic images of such inhomogeneous material contain a nonuniform distribution of anomalies and few, if any, geometrically regular features which can be assessed to establish material integrity. Results obtained with our new algorithms show, for certain discriminants, a high degree of correlation between the numerical accept/reject values obtained from acoustic image processing and the time-to-failure of the graphitic material in simulated atmospheric reentry tests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570729
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...