Mechanics |
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2008, No. 3
M.M. Aliev, N.G. Karimova
VARIANT CRITERION OF STRENGTH FOR ISOTROPIC POLYMERS
In the paper a new criterion of strength for isotropic polymers under hydrostatic pressure conditions is considered. The results of comparison with the strength criterion as the exponential function between the first invariant of stresses tensor and the second invariant of the stresses deviator as well as with the known criteria of strength Ballandin, Drucker- Prager are received. In comparison with the strength criteria for isotropic materials the new criterion advantage is that it has only two strength parameters (tensile and compressive strength limit).
S.A. Grishin
ON THE PROBLEM FORMULATION FOR THE TECHNICAL THEORY OF SHELLS IN MIXED FORM
The flutter problem for a conical clamped-free shell under influence of the supersonic gas flow out from it is investigated. The shell is assumed to be elastic isotropic and homogeneous and described by equations of the technical theory of shells in the mixed form [1]. In that case two scalar functions on the shell middle surface: the normal deflexion and the membrane-stress potential are required to find. The boundary conditions therefore also must be formulated in terms of these functions and their derivatives. It is extremely important that the mechanical system be conservative when no flow interacts with it.
V.N. Kukudzhanov, A.V. Kolomiec
On the base of elastoplastic model taking into account a generation and a growth of mesodefects a bending of two layered plate under displacement of a rigid indentor is considered. The process of plastic strain localization in adiabatic shear bands and loss of rheological stability was investigated. The qualitative difference for these processes in the homogeneous and inhomogeneous strain-stress states is discussed. It is shown that varying size and type of finite elements does not change the distribution of bands of plastic strain localization. Numerical analytical method based on splitting of elastoplastic constitutive equations and adaptive Lagrangian- Eulerian mesh are used for the integration of the problem. The plastic strain band localization is investigated for two layers plates for different boundary condition (for free supported and rigid clamped plate) and for different layers material properties. The local criterion of failure is proposed and the indentor limit displacement related to lose of the carrying capacity are determined taking into account difference of the material structure.
N.I. Konovalova, S.I. Martynov
NON-STATIONARY VISCOUS FLOW AROUND OF TWO SPHERES
The problem of non-stationary viscous flow liquid around of two spheres is considered. The speed of liquid is time-periodical homogeneous function of coordinates. Hydrodynamic interaction of particles taken into account. The solution of problem is obtained in terms of small parameter. The forces and torques exerting on spheres are calculated. The analysis of possibility to obtain the expressions for average force and torque in mixture with precision to items by volume concentration degree of elements above first is analyzed.
P.V. Manahov, O.B. Fedoseev
In this article the problem of the plastic bodies calculate on the theory of plastic flow has been set out. Alternative method based on a system of nonlinear equations solution by software tools realizing residual minimization algorithm of a function has been proposed. The examples of the routine problems solution of mechanics have been presented using the suggested approach to determination of plastic deformation. Estimate of the method outlooks has been accomplished.
Y.N. Radayev
A NEW STUDY OF PLANE STRAIN STATE OF A PERFECTLY PLASTIC SOLID
A new approach to derivating and study of plane strain state of a perfectly plastic solid is proposed. Unlike previous discussions in the perfect plasticity originating from the studies given by H.Hencky and L. Prandtl all requisite equations are obtained from three-dimensional equations formulated for states corresponding to an edge of the Tresca prism simply by reducing their dimension.
M.K. Khasanov
GAS INJECTION IN THE POROUS MEDIUM WITH FORMATION OF GASHYDRATE
The particularities of the formation gas hydrate at injection of the gas into porous media, in initial condition filled by gas and water are considered. The hydrate can be forming on frontal surface and in longitude area. The conditions, under which each hydrate forming mode is realized are defined.