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  • 1
    Electronic Resource
    Electronic Resource
    An inverse scattering method to characterize inhomogeneities in elastic solids (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 2771-2777 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An inverse method for ultrasonic scattering data is proposed to characterize a single elastic inhomogeneity of general shape contained in an elastic solid. The method is based on an integral representation for the scattered field in the frequency domain. The method has been applied at both large and intermediate wavelengths as compared with a characteristic length parameter of the scatterer. For a given scattered field the inverse problem has been formulated as a nonlinear optimization problem. At low frequencies its solution gives the location of the centroid of the scatterer, the equivalent force vector, and the moment tensor. In addition, the interaction energy between the material and the inclusion is obtained for a related static stress state. This latter result may have relevance to failure conditions in the material under service conditions. For intermediate frequencies, the volume and elastic constants of an equivalent spherical inhomogeneity are obtained, in addition to its position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339405
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Reflection and transmission of plane waves by a layer of compact inhomogeneities (1988)
    Springer
    Pure and applied geophysics 128 (1988), S. 101-118 
    Details
    ISSN: 1420-9136
    Keywords: Reflection ; transmission ; plane waves ; compact inhomogeneities ; cracks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reflection and transmission of elastic wave motion by a layer of compact inhomogeneities has been analyzed. For identical inhomogeneities whose geometrical centers are periodically spaced, the problem has been formulated and solved rigorously. The reflected and transmitted longitudinal and transverse wave motions have been expressed as superpositions of wavemodes, where each wavemode has its own cut-off frequency. At its cut-off frequency a mode converts from a standing into a propagating wavemode. The standing wavemodes decay exponentially with distance to the plane of the centers of the inhomogeneities. At small frequencies only the lowest order modes of longitudinal and transverse wave motion are propagating. Reflection and transmission coefficients have been defined in terms of the coefficients of the zeroth-order scattered wavemodes. These coefficients have been computed by a novel application of the Betti-Rayleigh reciprocal theorem. They are expressed as integrals over the surface of a single inhomogeneity, in terms of the displacements and tractions on the surface of the inhomogeneity. The system of singular integral equations for the surface fields has been solved numerically by the boundary integral equation method. Curves show the reflection and transmission coefficients for the reflected and transmitted longitudinal and transverse waves as functions of the frequency. Some results are also presented for planar distributions of cracks whose spacing and size are random variables. Finally, dispersion relations are discussed for solids which are completely filled with periodically spaced inhomogeneities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01772592
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Interfacial waves in pre-stressed compressible elastic media (1998)
    Springer
    Computational mechanics 21 (1998), S. 293-299 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The propagation of elastic interfacial waves along the plane boundary separating two pre-stressed compressible half-spaces is examined. The underlying finite strain in each medium is homogeneous with the principal axes of strain in the two media aligned, one axis being normal to the interface. For arbitrary strain energy functions and arbitrary material, pre-stress and pre-strain parameters the secular equation is derived for the phase speed of interfacial waves propagating along a principal pre-strain axis. It is found, among other results, that for in-plane equibiaxial stretching the secular equation does not explicitly contain the Cauchy principal stresses and that media of the same density cannot sustain propagating interfacial waves. Particular attention is paid to the analysis of the secular equation for stress-free fluids overlying pre-stressed solids. The range of existence of propagating interfacial waves is found to be independent of the fluid overlying the pre-stressed solid. Numerical examples are considered not only to illustrate graphically the analytical results of the effect of pre-stress on interfacial waves but also to complement them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004660050305
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Dispersion of elastic waves in periodically inhomogeneous media (1993)
    Springer
    Computational mechanics 12 (1993), S. 134-146 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Propagation of time-harmonic elastic waves through periodically inhomogeneous media is considered. The material inhomogeneity exists in a single direction along which the elastic waves propagate. Within the period of the linear elastic and isotropic medium, the density and elastic modulus vary either in a continuous or a discontinuous manner. The continuous variations are approximated by staircase functions so that the generic problem at hand is the propagation of elastic waves in a medium whose finite period consists of an arbitrary number of different homogeneous layers. A dynamic elasticity formulation is followed and the exact phase velocity is derived explicitly as a solution in closed form in terms of frequency and layer properties. Numerical examples are then presented for several inhomogeneous structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371989
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamic analysis of inelastic plates by the D/BEM (1994)
    Springer
    Computational mechanics 13 (1994), S. 276-284 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A direct boundary element method is developed for the dynamic analysis of thin inelastic flexural plates of arbitrary planform and boundary conditions. It employs the static fundamental solution of the associated elastic problem and involves not only boundary integrals but domain integrals as well. Thus boundary as well as interior elements are employed in the numerical solution. Time integration is accomplished by the explicit algorithm of the central difference predictor method. A viscoplastic constitutive theory with state variables is employed to model the material behaviour. Numerical results are also presented to illustrate quantitatively the proposed method of solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350229
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    On stress conditions and computations at bi-material interfaces (1998)
    Springer
    Computational mechanics 21 (1998), S. 300-305 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Conditions on stresses and their first spatial derivatives across a flat bi-material interface in three-dimensional linear dynamic elasticity are obtained by replacing the displacement continuity condition with continuity conditions on in-plane strains and curvatures. The stresses on one side of interfaces and near them in multi-constituent structures are readily computed using these conditions-formulae and not solving the full problem, if the stresses on the other side have been computed having solved the full problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004660050306
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    Paper (German National Licenses)
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  • 7
    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
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  • 8
    Electronic Resource
    Electronic Resource
    BEM analysis of reduced dynamic stress concentration by multiple holes (1993)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 9 (1993), S. 917-924 
    Details
    ISSN: 1069-8299
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The reduction of stress concentration around a circular hole in a dynamically loaded plate by introducing auxiliary holes around the original hole is studied numerically. The solution of this plane stress problem is carried out in the Laplace transformed domain with the aid of the boundary-element method, and subsequently the time domain response is obtained by numerically inverting the transformed solution. Numerical examples are presented which demonstrate a stress reduction as high as 18 per pent by the introduction of two auxiliary holes in the loading direction for the uniaxial case.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640091108
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