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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 37 (1980), S. 65-74 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Auf der Basis von Mindlins Theorie des elastischen Dielektrikums und mit Benutzung der Papkovitch-Darstellungen für Verschiebungs- und Polarisationsvektoren wird mit Hilfe von Fourier-Transformationen eine allgemeine Lösung für Randwertprobleme einer Halbebene mit einer beliebigen Ladungsverteilung gefunden. Es werden explizite Ausdrücke für verschiedene mechanische und elektrische Potentiale für eine Punktladung an der Berandung des elastischen, dielektrischen Halbraums erhalten.
    Notes: Summary Using Papkovitchtype representations for the displacement and polarization vectors and Fourier transforms, a general solution to boundary value problems of a half plane subjected to an arbitrary charge distribution is constructed within Mindlin's theory of elastic dielectrics. Explicit expressions for various mechanical and electric potentials are obtained for a point charge located on the boundary of the elastic dielectric half-space.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 65 (1987), S. 181-204 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The safe load limit, a well defined parameter for columns made of linearly viscoelastic solid-type materials with limited creep, is generalized to materially and geometrically nonlinear viscoelastic structures. To illustrate the concepts to be treated, a simple rigid bar-spring/dashpot model simulating the behaviour of imperfect columns is analyzed in detail. Next the imperfect column problem is formulated and solved. Various approximations in the solution technique are introduced which allow relatively simple procedures for the evaluation of the safe load limit. Finally a column made of concrete is analyzed in detail for which the results are compared, where possible, with experimental data, a comparison which shows satisfactory agreement.
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  • 3
    ISSN: 1573-1529
    Keywords: Coal mining ; longwall mining ; subsidence ; stress distribution ; finite element analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary A two dimensional finite element procedure is applied to simulate a coal mining excavation sequence. A procedure with linear solution steps is developed and applied to an idealized mountain cross-section with exceptionally thick coal seams and large dip angle. The results provide information on pillar pressure, floor and roof stability, displacement characteristics and surface subsidence.
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  • 4
    ISSN: 1573-1529
    Keywords: Finite element analysis ; stress distribution ; coal mining ; underground mining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary and conclusions Particular features of the finite element procedure presented here and used for mining sequence simulations, are summarized as follows: (1) Different types of pre-mining stress states can be treated. (2) A mining sequence with options in relief force applications can be simulated. (3) Closure of previously mined openings is indicated. (4) Modelling of rock joints and faults is possible. (5) Nonlinearities in the rock mass, due to plastification and due to tension cracking, can be handled. Two finite-element models representing typical mining conditions within the present study are used in a series of sample analyses to demonstrate the above capabilities. The nonlinear analysis for both plastification and tension showed good convergence characteristics. In a follow-up study the procedure will be used for actual field situations in order to evaluate stress and displacement fields, pillar pressures and surface subsidence. Of particular interest within the present project will be the numerical investigation of large span mining openings under different initial stress conditions as well as the influence of different fault or joint properties on the mining environment.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 14 (1974), S. 290-296 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Experimental investigation of the elastoplastic and ultimate load response of thick hemispheres with cylindrical skirts is presented. A shell with a hinged boundary condition, loaded symmetrically, and one having a fixed edge, with unsymmetric lateral load, were tested. Electrical-resistance bonded foil strain gages and photoelastic surface coatings were used in monitoring the strain response while spring-activated dial gages were used in recording displacements. Both panchromatic and color still photographs were utilized in observing the photoelastic patterns, while the failure mode of one model was recorded by means of high-speed motion pictures.
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  • 6
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper describes part of an experimental program aimed at studying the elasto-plastic large-deflection behavior of an orthotropic steel bridge-deck plate. After several tests, loading the plate into the large-deflections region, a final test to failure was carried out. Two concentrated loads applied symmetrically at midspan were used to produce large-scale yielding in the main girders, the floor beams, the ribs and the deck plate, particularly in the vicinity of the loads. The load-deflection and load-strain characteristics were monitored up to failure and are reported herein.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 11 (1971), S. 254-262 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents the experimental part of a study of the elastic stability of clamped and hinged spherical and paraboloidal shell caps subjected to external uniform pressure loading. Ninety-six poly-vinyl-chloride (PVC) shells of 15-in. base diameter and formed by thermovacuum process, were tested and their critical loads recorded. The effects of geometry, clamped and hinged boundary conditions, height/span and radius of curvature/thickness ratios on the critical pressure were investigated. The results are compared, where possible, with experimental data obtained by previous investigators.
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  • 8
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents part of an experimental study aimed at investigating the static response of thick cylinders with spherical heads subjected to symmetric and unsymmetric localized surface loads. In addition, thermal strains due to various steady-state surface-temperature differences are presented. Empirical strains and displacements are compared, where possible, with analytical predictions based on a linear classical thick-shell theory.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of elasticity 6 (1976), S. 295-311 
    ISSN: 1573-2681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Durch Anwendung der Assoziativ-Matrizen-Methode werden Galerkinische Darstellungen für den Verschiebungsvektor, den Polarisierungsvektor und die potentiellen Prüffelder einer statischen ebenen Theorie des elastischen Dielektrikums entwickelt. Von den singulären Lösungen der harmonischen, biharmonischen und Helmholtz-Gleichungen werden grundlegende Matrizenlösungen für das unendliche, ebene und elastische Dielektrikum, das durch konzentrierte Raumkräfte, elektrische Kräfte und Ladungsdichte beansprucht wird, abgeleitet. Unter Verwendung der Randwert-OperatorenY, Z, M, der grundlegenden Matrizen-Lösungen und Betti's Formel, wird eine Spezial-Matrize Λ(x, y) konstruiert und eine Integraldarstellung für (u 1,u 2,P 1,P 2, ϕ) erhalten. Unstetigkeitssätze werden für das Doppelschicht-Potential und denQ-Operator eines einschichtigen Potentials angeführt. Durch Anwendung dieser Sätze werden die Lösungen der inneren und äusseren Grenzwertprobleme zur Lösung eines Systems von fünf singulären Integralgleichungen reduziert. Der Index eines der Systeme wird als Null bewiesen und es wird die Schlussfolgerung gezogen, dass der Fredholmsche Satz und seine Alternativen fur diese Theorie anwendbar sind.
    Notes: Abstract Representations of Galerkin type are obtained for the displacement vector, polarization vector and the potential fields in the static plane theory of elastic dielectrics using the method of associated matrices. Fundamental matrix solutions of an infinite elastic dielectric plane subjected to a concentrated body force, electric force and charge density are derived from the singular solutions of harmonic, biharmonic and Helmholtz equations. Using boundary operatorsY, Z, M, the fundamental matrix solutions, and Betti's formulae, a matrix Λ(x, y) is constructed and an integral representation for (u 1,u 2,P 1,P 2, ϕ) is obtained. Discontinuity theorems are stated for the double layer potential andQ operator of the single layer potential. By means of these theorems, the solutions of interior and exterior boundary value problems are reduced to the solution of a system of five singular integral equations. The index of one of the systems is shown to be zero and it is concluded that Fredholm theorems and its alternatives hold.
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  • 10
    ISSN: 1573-2681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Elementary matrix multiplications and inversions lead to Galerkin type representations for the steady-state vibration equations of linear classical elasticity, thermoclasticity, Mindlin's couple stress and Eringen's micropolar theories of elasticity. The use of representations and the equations satisfied by potentials is further illustrated by obtaining singular solutions. Some of the results agree with known solutions.
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