共查询到20条相似文献,搜索用时 46 毫秒
1.
D. N. Gorelov 《Journal of Applied Mechanics and Technical Physics》2007,48(2):184-191
A general formulation of a nonlinear initial-boundary problem of an unsteady separated flow around an airfoil by an ideal
incompressible fluid is considered. The problem is formulated for a complex velocity. Conditions of shedding of vortex wakes
from the airfoil are analyzed in detail. The proposed system of functional relations allows constructing algorithms for solving
a wide class of problems of the wing theory.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 2, pp. 48–56, March–April, 2007. 相似文献
2.
A. A. Kalyakin 《Journal of Applied Mechanics and Technical Physics》2006,47(3):446-454
Plane and axisymmetric contact problems for a three-layer elastic half-space are considered. The plane problem is reduced
to a singular integral equation of the first kind whose approximate solution is obtained by a modified Multhopp-Kalandiya
method of collocation. The axisymmetric problem is reduced to an integral Fredholm equation of the second kind whose approximate
solution is obtained by a specially developed method of collocation over the nodes of the Legendre polynomial. An axisymmetric
contact problem for an transversely isotropic layer completely adherent to an elastic isotropic half-space is also considered.
Examples of calculating the characteristic integral quantities are given.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 165–175, May–June, 2006. 相似文献
3.
A. M. Khludnev 《Journal of Applied Mechanics and Technical Physics》2008,49(4):553-567
The contact problem for two elastic plates aligned at a prescribed angle to each other is considered. The set of contact points
is assumed to be unknown in advance and to be determined only after the problem is solved. Various formulations of the problem
are given, and their equivalence is proved. A complete set of boundary conditions fulfilled on the contact domain is found,
and the character of satisfaction of these conditions is described. The asymptotic properties of solutions are studied for
rigidity parameters of the contacting plates tending to infinity.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 4, pp. 42–58, July–August, 2008. 相似文献
4.
V. A. Kovtunenko I. V. Sukhorukov 《Journal of Applied Mechanics and Technical Physics》2006,47(5):704-713
For the evolutionary problem describing crack propagation in a solid with allowance for the irreversible work of plastic deformation
due to the crack propagation, a general optimization formulation is proposed and investigated. For the optimum crack, data
on the H2-smoothnesses of the displacement field in the solid and, hence, on the finiteness of the stress at the crack tip, are obtained.
The solvability of the optimization problem (i.e., the existence of an optimum crack) is proved for a curvilinear crack propagation
path specified a priori. For the particular case of a straight path, a generalized criterion of crack growth is proposed.
The question of the choice of a crack propagation path is discussed and a comparison with existing fracture criteria is made.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 5, pp. 107–118, September–October, 2006. 相似文献
5.
When a nonhomogeneous solid is melting from below, convection may be induced in a thermally–unstable melt layer. In this study,
the onset of buoyancy-driven convection during time-dependent melting is investigated by using similarly transformed disturbance
equations. The critical Darcy–Rayleigh numbers based on the melt-layer thickness, Ra
H,c, are found numerically for various conditions. For small superheats, the present predictions show that Ra
H,c is located between 27.1 and 4π
2 and it approaches the well-known results of the original Horton–Rogers–Lapwood problem. However, for high superheats, it
is dependent on the phase change rate λ and the relation of Ra
H,c λ = 25.89 is shown. 相似文献
6.
V. P. Zhitnikov O. R. Zinnatullilna S. S. Porechnyi N. M. Sherykhalina 《Journal of Applied Mechanics and Technical Physics》2009,50(4):617-627
Numerical solution of the Hele-Shaw problem reduces to solution of three boundary-value problems of determining analytic functions
of a complex variable in each time step: conformal mapping of the range of the parametric variable to the physical plane,
the Dirichlet problems for determining the electric-field strength, and the Riemann-Hilbert problem for calculating partial
time derivatives of the coordinates of points of the interelectrode space (the images of the points on the boundary of the
parametric plane are fixed). Unlike in the two-dimensional problem, the electric-field strength is determined using integral
transformations of an analytic function. Approximation by spline function is performed, and more accurate and steady (than
the well-known ones) general solution algorithms for the nonstationary axisymmetric problems are described. Results of a numerical
study of the formation of stationary and self-similar configurations are presented.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 87–99, July–August, 2009. 相似文献
7.
A. A. Dolzhkovoi N. N. Popov V. P. Radchenko 《Journal of Applied Mechanics and Technical Physics》2006,47(1):134-142
The physically and statistically nonlinear problem of steady-state creep for a thick-walled tube loaded by internal pressure
is solved in the third approximation using the small-parameter method. The variances of random creep strain rates and displacements
are calculated. The results obtained are compared with the solution of the same problem in the first and second approximations.
A reliability assessment method for the tube using the strain failure criteria is proposed.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 1, pp. 161–171, January–February, 2006. 相似文献
8.
O. S. Dunaeva N. B. Il’inskii 《Journal of Applied Mechanics and Technical Physics》2008,49(6):971-977
A problem of modification of the classical airfoils that ensure the absence of separation in a subsonic ideal-gas flow in
a specified range of angles of attack is solved by a numerical-analytical method based on the quasi-solution of inverse boundary-value
problems of aerohydrodynamics and Kármán-Jiang formulas. Loitsyanskii’s criterion of the non-separated flow is used to determine
the boundary-layer separation point.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 99–106, November–December, 2008. 相似文献
9.
A. N. Ermolenko 《Journal of Applied Mechanics and Technical Physics》2007,48(2):166-175
The stability of the state of rest of a heated infinite horizontal layer of a viscous heat-conducting fluid (the Rayleigh-Benard
problem) is considered. The equation of state for the fluid takes into account the nonmonotonic temperature and pressure dependence
of water density. Instability of the mechanical equilibrium with respect to small monotonic perturbations is studied. The
effect of the problem parameters on the Rayleigh numbers and their corresponding critical motions is investigated numerically
using linear theory. Numerical investigation of the spectral problem is based on the Godunov-Abramov orthogonalization method.
The calculation results are compared with the well-known results for the limiting case where the density is considered a quadratic
function of temperature and does not depend on pressure.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 2, pp. 27–38, March–April, 2007. 相似文献
10.
A. A. Zelenina 《Journal of Applied Mechanics and Technical Physics》2006,47(4):600-607
The problem of the torsion and tension-compression of a prismatic bar with a stress-free lateral surface is studied using
three-dimensional elasticity theory for materials with moment stresses. A substitution is found that allows one to separate
one variable in the nonlinear equilibrium equations for a Cosserat continuum and boundary conditions on the lateral surface.
This substitution reduces the original spatial problem of the equilibrium of a micropolar body to a two-dimensional nonlinear
boundary-value problem for a plane region shaped like the cross section of the prismatic bar. Variational formulations of
the two-dimensional problem for the section are given that differ in the sets of varied functions and the constraints imposed
on their boundary values.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 167–175, July–August, 2006. 相似文献
11.
The problem of the onset of convective roll instabilities in a horizontal porous layer with isothermal boundaries at unequal
temperatures, well known as the Horton–Rogers–Lapwood problem, is revisited including the effect of pressure work and viscous
dissipation in the local energy balance. A linear stability analysis of rolls disturbances is performed. The analysis shows
that, while the contribution of viscous dissipation is ineffective, the contribution of the pressure work may be important.
The condition of marginal stability is investigated by adopting two solution procedures: method of weighted residuals and
explicit Runge–Kutta method. The pressure work term in the energy balance yields an increase of the value of the Darcy–Rayleigh
number at marginal stability. In other words, the effect of pressure work is a stabilizing one. Furthermore, while the critical
value of the Darcy– Rayleigh number may be considerably affected by the pressure work contribution, the critical value of
the wave number is affected only in rather extreme cases, i.e. for very high values of the Gebhart number. A nonlinear stability
analysis is also performed pointing out that the joint effects of viscous dissipation and pressure work result in a reduction
of the excess Nusselt number due to convection, when the Darcy–Rayleigh number is replaced by the superadiabatic Darcy–Rayleigh
number. 相似文献
12.
I. Yu. Tsvelodub 《Journal of Applied Mechanics and Technical Physics》2006,47(3):390-393
A problem of the theory of elasticity is considered for a body with vectors of displacements u and loads p simultaneously defined on one part of the body and with undefined conditions on the remaining part of the body. For a doubly
connected domain, where the vectors u and p are set on one of its boundaries (inner or outer), an iterative method based on reduction of the initial problem to a sequence
of mixed problems is justified.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 100–103, May–June, 2006. 相似文献
13.
I. M. Arkhipova V. Yu. Chirkov 《Journal of Applied Mechanics and Technical Physics》2008,49(6):1055-1062
The problem of slow dynamic contact interaction of a system of punches remote from each other with an elastic half-space surface
in the absence of friction is studied under the assumptions that the diameters of the contact areas are smaller than the minimum
distance between the punches and the time required for the shear wave to travel the distance equal to the punch diameter is
comparable to the time scale of the process. A first-order asymptotic model is constructed. As an example, the case of steady-state
vibrations of a system of two punches is considered.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 198–206, November–December, 2008. 相似文献
14.
The paper presents a method to identify a system of several nonstationary independent transverse loads on a rectangular plate
of medium thickness. The input data for solving the inverse problem are time-dependence of displacements or strains given
at some points of the plate. Examples of numerical calculations to identify two or three loads are presented. The deformation
of plates is modeled using a refined Timoshenko theory. Tikhonov’s regularizing algorithm is used to solve the Volterra equations
for the unknown loads
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Translated from Prikladnaya Mekhanika, Vol. 43, No. 7, pp. 90–97, July 2007. 相似文献
15.
The nonstationary indentation of a rigid blunt indenter into an elastic layer is studied. An approach to solving a mixed initial-boundary-value
problem with an unknown moving boundary is developed. The problem is reduced to an infinite system of integral equations and
the equation of motion of the indenter. The system is solved numerically. The analytical solution of the nonmixed problem
is found for the initial stage of the indentation process
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Translated from Prikladnaya Mekhanika, Vol. 44, No. 3, pp. 55–65, March 2008. 相似文献
16.
N. M. Borodachev 《International Applied Mechanics》2006,42(7):744-748
It is shown that three equilibrium equations and three stress compatibility equations are sufficient to solve the stress problem
of elasticity
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 7, pp. 23–28, July 2006. 相似文献
17.
A. V. Yasinskii 《International Applied Mechanics》2008,44(1):34-40
The problem of identifying the law of time variation in the temperature of one boundary surface of a two-layer cylinder and
its thermal and thermostressed state from the temperature and radial displacement of the other surface is formulated and solved.
The inverse problem of thermoelasticity to which the problem posed is reduced is analyzed for well-posedness. The solution
of the direct problem of thermoelasticity is used to numerically test the technique of solving the inverse problem
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Translated from Prikladnaya Mekhanika, Vol. 44, No. 1, pp. 40–47, January 2008. 相似文献
18.
S. V. Bosakov 《International Applied Mechanics》2008,44(4):413-418
Rektorys’ approach is used in implementing the Ritz method to solve the contact problem for a circular punch on an elastic
foundation of general form
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Translated from Prikladnaya Mekhanika, Vol. 44, No. 4, pp. 65–71, April 2008. 相似文献
19.
This work studies the response of bodies governed by dipolar gradient elasticity to concentrated loads. Two-dimensional configurations
in the form of either a half-space (Flamant–Boussinesq type problem) or a full-space (Kelvin type problem) are treated and
the concentrated loads are taken as line forces. Our main concern is to determine possible deviations from the predictions
of plane-strain/plane-stress classical linear elastostatics when a more refined theory is employed to attack the problems.
Of special importance is the behavior of the new solutions near to the point of application of the loads where pathological
singularities and discontinuities exist in the classical solutions. The use of the theory of gradient elasticity is intended
here to model material microstructure and incorporate size effects into stress analysis in a manner that the classical theory
cannot afford. A simple but yet rigorous version of the generalized elasticity theories of Toupin (Arch. Ration. Mech. Anal.
11:385–414, 1962) and Mindlin (Arch. Ration. Mech. Anal. 16:51–78, 1964) is employed that involves an isotropic linear response and only one material constant (the so-called gradient coefficient)
additional to the standard Lamé constants (Georgiadis et al., J. Elast. 74:17–45, 2004). This theory, which can be viewed as a first-step extension of the classical elasticity theory, assumes a strain-energy
density function, which besides its dependence upon the standard strain terms, depends also on strain gradients. The solution
method is based on integral transforms and is exact. The present results show departure from the ones of the classical elasticity
solutions (Flamant–Boussinesq and Kelvin plane-strain solutions). Indeed, continuous and bounded displacements are predicted
at the points of application of the loads. Such a behavior of the displacement fields is, of course, more natural than the
singular behavior present in the classical solutions.
相似文献
20.