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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 19 (1968), S. 501-509 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Zusammenfassung Das dynamische Durchschlagen eines masselosen symmetrischen elastischen Dreigelenkbogens, der eine Punktmasse am mittleren Gelenk trägt, wird untersucht. Eine längs der Symmetrieachse wirkende Last wird plötzlich aufgebracht und weiterhin konstant gehalten. Es zeigt sich, dass die kritische Last durch geometrische Unvollkommenheiten stark vermindert wird.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 19 (1968), S. 492-501 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Zusammenfassung Eine explizite Form der Dissipationsfunktion für thermomechanische Vorgänge in viskoelastischen Körpern wird abgeleitet. Diese Funktion hängt von beobachtbaren Grössen, wie z. B. Spannungs- und Dehnungsgeschwindigkeiten und ihren zeitlichen Ableitungen ab. Die Formulierung basiert auf der irreversiblen Thermodynamik deformierbarer Körper, die vonBiot entwickelt und vonZiegler undSchapery verallgemeinert wurde. Die vorgeschlagene Dissipationsfunktion ist sowohl zum experimentellen als auch zum theoretischen Gebrauch geeignet.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of optimization theory and applications 4 (1969), S. 277-298 
    ISSN: 1573-2878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, minimum-weight design of an elastic sandwich beam with a prescribed deflection constraint at a given point is investigated. The analysis is based on geometrical considerations using then-dimensional space of discretized specific bending stiffness. Since the present method of analysis is different from the method based on the calculus of variations, the conditions of piecewise continuity and differentiability on specific bending stiffness can be relaxed. Necessary and sufficient conditions for optimality are derived for both statically determinate and statically indeterminate beams. Beams subject to a single loading and beams subject to multiple loadings are analyzed. The degree to which the optimality condition renders the solution unique is discussed. To illustrate the method of solution, two examples are presented for minimum-weight designs under dual loading of a simply supported beam and a beam built in at both ends. The present analysis is also extended to the following problems: (a) optimal design of a beam built in at both ends with piecewise specific stiffness and a prescribed deflection constraint and (b) minimum-cost design of a sandwich beam with prescribed deflection constraints.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of optimization theory and applications 15 (1975), S. 37-49 
    ISSN: 1573-2878
    Keywords: Calculus of variations ; minimum-weight design ; structural design ; structural optimization ; optimal structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper is concerned with the minimum weight design of an elastic cable of variable cross section with both ends positioned at the same level. The cable is under the action of a uniformly distributed load. With the deflection of the cable given and the stress in the cable restricted, our objective is to determine the optimum distribution of the cross section. Calculus of variations with equality and inequality constraints is employed to find the necessary conditions of optimality. Efficiency of the optimum design evaluated from the comparison of an optimum cable with an equivalent cable of uniform cross section is studied. The best sag-span ratio of the optimum cable is also determined.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 29 (1985), S. 143-155 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé Le mémoire est relatif à la propagation d'une fissure superficielle dans un corps fragile sous l'effet de la pénétration d'un coin aigu dans la fissure à une vitesse constante. L'analyse du problème est basée sur un modèle en double poutre cantilever, où l'on ne considère que les déformations de cisaillement. Le critère de rupture utilisé est le concept de Griffith d'équilibre des énergies. On trouve que la propagation de la fissure débute lorsque le front d'onde de cisaillement atteint l'extrémité de la fissure initiale. Au cours de sa propagation, la fissure atteint une vitesse qui demeure constante, quoique comportant des ressauts d'amplitude finie chaque fois que le front d'onde de cisaillement atteint l'extrémité de la fissure en mouvement. Les résultats obtenus par une analyse dynamique sont en accord approximatif avec ceux que l'on obtient par une analyse quasistatique.
    Notes: Abstract This paper is concerned with the propagation of a surface crack in a brittle solid induced by the indentation of a sharp wedge into the crack under constant speed. The analysis is based on a double-cantilever-beam model. Only the shear deformation of the cantilever is considered. Griffith concept of the balance of energy is used as the fracture criterion. It is found that crack propagation begins when the shear wave front is at the tip of the initial crack. During crack propagation, the crack speed remains constant with finite jumps at those moments when the shear wave front reaches the tip of the running crack. The results obtained by the dynamic analysis agree approximately with those derived from a quasi-static analysis.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 48 (1991), S. 299-309 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The problem of plane stress crack growth in a rectangular linearly viscoelastic plate under a pair of equal and opposite forces applied to the crack surface is studied experimentally. A fatigue crack is generated at the end of a slot cut on the specimen. After application of two opposite forces to the specimen with a fatigue crack, the crack grows gradually. It is found that under sufficiently small load, the speed of crack growth decreases as time increases, and crack arrest occurs finally. However when the applied load is sufficiently large, the crack grows with increasing speed until a catastrophic failure of the specimen takes place. Between these two extreme cases, the crack grows with an oscillatory speed. A theory based on the models of an infinite plate and double cantilevers is proposed for the explanation of the behaviour of crack growth under various loads. Our experimental results check fairly well with theoretical predictions.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 23 (1983), S. 23-35 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé On étudie la mécanique associée au fendage d'une bande par la pénétration d'une lame aiguë le long de son axe médian. On considère en premier lieu le problème sous l'angle quasi-statique. La propagation de la fissure peut être associée à la perte de stabilité qui se produit lorsque la charge appliquée atteint la valeur critique entraînant une bifurcation. Ensuite, on étend au cas dynamique le problème statique, en incluant dans l'analyse la force d'inertie de la lame. On formule les conditions initiales afférant au mouvement de la lame. Pour toute charge agissant sur celle-ci, on peut déterminer la vitesse critique de la lame qui conduit à une propagation indéfinie de la fissure, en recourant à la théorie de la stabilité dynamique. Enfin, on envisage le cas du fendage d'une bande sous l'application répétée de charges pulsées. Le nombre critique d'application de ce type de charge conduisant à propagation indéfinie de la fissure est déterminée par voie numérique.
    Notes: Abstract This paper deals with the mechanics involved in splitting a strip through penetration with a sharp wedge along the center line. First, a quasi-static problem is considered. The crack propagation can be associated with the loss in stability when the applied load reaches the critical value for bifurcation. Next, the static problem is extended to a dynamic case by including the inertia force of the wedge in the analysis. An initial value problem is formulated for the motion of the wedge. For any given weight of the wedge, the critical velocity of the wedge for indefinite crack propagation can be determined by means of the theory of dynamic stability. Finally, the case of splitting a strip under repeated applications of impulsive load is considered. The critical number of applications of impulsive load for indefinite crack propagation is determined numerically.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 14 (1990), S. 1-26 
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A number of variational principles are established in this paper for the stress analysis of porous media with compressible constituents. A three-dimensional finite element method is proposed based on the variational principle. The finite element method thus established is applied to the study of the temperature, deformation and flow field associated with the water-flood technique in secondary recovery projects for oil exploration. In the study model, the layout of injection wells and production wells is considered to have a regular pattern where symmetry conditions exist. The injection fluid diffuses slowly into the formation through a vertical crack which is initially generated by an explosion. The problem is analysed by a plane strain formulation with the effects of heat conduction and convection included.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 15 (1992), S. 545-569 
    ISSN: 0271-2091
    Keywords: Oil recovery ; Porous medium ; Conductive fracture ; Finite element method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In the technology of oil recovery the oil production rate can be increased by generation of a vertical sand-filld conductive fracture on the wall of the well. Oil diffuses through the conductive fracture to the well. In this paper the seepage flow and isothermal deformation fields in both the formation and fracture and the oil production rate at the well are studied by modelling the formation as an infinite poroelastic medium saturated with a one-phase compressible fluid. The fracture is treated as a one-dimensional poroelastic medium. Darcy flows are considered in both the formation and fracture. The plane strain condition is imposed. Our solution is obtained numerically by a finite element method based on a variational principle. The accuracy of the analysis is studied by comparison of the numerical solutions of some problems with their analytical solutions. Since we are dealing with the transient flow problem of an infinite region, an extrapolation technique is employed to find the finite element solution. The production rate of a well with the conductive fracture is compared with that of a well without the conductive fracture.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2013-09-11
    Description: Author(s): N. Xu, X. Shi, P. K. Biswas, C. E. Matt, R. S. Dhaka, Y. Huang, N. C. Plumb, M. Radović, J. H. Dil, E. Pomjakushina, K. Conder, A. Amato, Z. Salman, D. McK. Paul, J. Mesot, H. Ding, and M. Shi Recent theoretical calculations and experimental results suggest that the strongly correlated material SmB 6 may be a realization of a topological Kondo insulator. We have performed an angle-resolved photoemission spectroscopy study on SmB 6 in order to elucidate elements of the electronic structure r... [Phys. Rev. B 88, 121102] Published Tue Sep 10, 2013
    Keywords: Electronic structure and strongly correlated systems
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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