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951.
M. Khurram Wadee M. Ahmer Wadee 《Journal of the mechanics and physics of solids》2007,55(5):1086-1102
The behaviour of tubes under conditions of pure bending is investigated for the cases where the material of which they are constructed is either orthotropic or of various Poisson's ratios. Large deflections and moderate nonlinear strains are considered and the modelling incorporates Timoshenko beam theory thereby allowing non-zero shear strains to develop. This in turn makes axially inhomogeneous deformation of the cross-section possible and, in particular, the compressed side can develop wrinkling. Numerical solutions are presented for various material types and tube dimensions and some interesting phenomena, such as mode interaction and jumping, are demonstrated. 相似文献
952.
Šubrt J. Balek V. Criado J. M. Pérez-Maqueda L. A. Večerníková Eva 《Journal of Thermal Analysis and Calorimetry》1998,53(2):509-517
Effects induced by grinding in synthetic goethite samples were studied. The products of α-FeOOH grinding were characterised
by means of DTA, TG/DTG coupled with EGA (Mass spectrometry detection), powder X-ray diffraction analysis, and surface area
determination.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
953.
Hugh D. Burrows Maria da Gra a Miguel Rui P.C. Pereira Nuno M.B. Proen a S nia M.C. Cardoso Carlos F.G.C. Geraldes M. Helena Gil Wyn Brown 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):459-465
The solution behaviour has been studied of a series of even chain length lead(II) carboxylates (octanoate to octadecanoate) and the odd chain length lead(II) heptadecanoate in a variety of non-complexing organic solvents and in alcohols. In agreement with previous studies, solubility increases dramatically above a certain temperature, which depends on solute concentration, chain length and solvent. This solution temperature is also affected by traces of water. These results are complemented by studies using vapour pressure osmometry, dynamic light scattering, 1H and 13NMR spectroscopy. The results in water-free systems are consistent with the formation of rather ill-defined, polydisperse aggregates, which increase in size with concentration and decrease with temperature. These show similar local structure to lamellar mesophases in the pure lead(II) carboxylates, and are suggested to be formed by solvent induced swelling and break-up of these mesophases. In the presence of water, a more ordered structure is formed, in which a few water molecules are suggested to be bound to the lead(II) carboxylate headgroup. 相似文献
954.
Guo Tianfu Department of Flight Vehicle Design Applied Mechanics Beijing University of Aeronautics Astronautics Beijing Yang Wei Department of Engineering Mechanics Tsinghua University Beijing 《Acta Mechanica Solida Sinica》1995,8(1):15-23
An abrupt damage model, taking full account of finite geometrychanges, is used to study both the shapes of damage zones and the stress strain fieldsfor a plane-strain tensile crack under the small-scale yielding condition. Two typicalcrack-tip damage profiles are simulated by the element vanish technique. The fracturetoughness increment due to damage dissipation is evaluated in terms of the energyrelease rate. 相似文献
955.
K. Panajotov M. Sciamanna I. Gatare M. Arizaleta Arteaga H. Thienpont 《Opto-Electronics Review》2008,16(4):337-346
In this paper we summarize the recent results on nonlinear dynamics of vertical-cavity surface-emitting lasers (VCSELs) which
are bearing the fingerprints of the particular polarization properties of VCSELs. Due to the surface emission and cylindrical
symmetry, VCSELs lack strong polarization anisotropy and may undergo polarization switching and polarization mode-hopping.
This provides new specificities to the rich nonlinear dynamics induced in VCSELs by an external perturbation. We unveil both
experimentally and theoretically these new specificities for the case of optical feedback, optical injection, and unidirectional
synchronization between VCSELs. 相似文献
956.
T.J. Delph J.A. Zimmerman J.M. Kunz 《Journal of the mechanics and physics of solids》2009,57(1):67-3416
The loss of mechanical stability is a general phenomenon that underlies a wide variety of features in the behavior of crystalline materials. In this paper, we present an instability criterion that is of general applicability, subject to the restriction of low temperatures. The criterion is applied to two situations, that of hydrostatically induced cavitation and of quasi-brittle crack growth due to mode I loading. As judged by the results of independent molecular statics simulations, the predictions of the criterion are quite accurate. 相似文献
957.
C. Fond 《Journal of Polymer Science.Polymer Physics》2001,39(17):2081-2096
The principal criteria used to predict cavitation in rubber materials are reviewed, and experimental evidence is recalled for three different configurations: in the bulk, in the vicinity of a rigid particle, and in small rubber particles embedded in a rigid polymer matrix. Two major classes of cavitation criteria are defined, those based on an elastic instability (i.e., related to a stress state and finite strains) and those based on the energy balance (i.e., involving surface energies). The different criteria, in which various hyperelastic behavior laws are considered, are compared in numerical applications, and the tendencies are derived. The particular case of accounting for the surface tension of the rubber, a parameter common to the stress state and the energy balance, is treated in detail. It appears that the understanding of the genesis of a microcavity in a rubber material, when no pre‐existing flaw is assumed, still constitutes a difficulty for the analysis of mechanical damage in polymers containing a rubber phase. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2081–2096, 2001 相似文献
958.
Painlevé test for integrability for the combined equations generated from Yang’s self-dual equations for SU (2) gauge fields and Charap’s equations for chiral invariant model of pion dynamics faces some peculiar situations that allow
none of the stages (leading order analysis, resonance calculation and checking of the existence of the requisite number of
arbitrary functions) to be conclusive. It is also revealed from a comparative study with the previous results that the existence
of abnormal behaviour at any of the stated stages may have a correlation with the existence of chaotic property or some other
properties that do not correspond to solitonic behaviour.
相似文献
959.
A subset of experimental fires, conducted in the Northern Territory, Australia, in July and August 1986, was analysed to examine the role of the convective Froude number and Byram’s energy criterion (Pw/Pf) in the behaviour of grassland fires. Forms of these dimensionless numbers were obtained from the literature as were functions relating independent variables in these formulations to measured quantities. It was found that Byram’s energy criterion is simply the inverse cube of the convective Froude number and thus, was not examined in detail. It was found that the convective Froude number is not reflected in the observed behaviour of fires, as previous authors have suggested, despite the range of experimental conditions (wind speed 1.5–7.5 ms−1, rate of spread 0.05–2.82 ms−1). 相似文献
960.