共查询到20条相似文献,搜索用时 15 毫秒
1.
E. K. Ankyanets 《International Applied Mechanics》2005,41(8):924-928
The vibrations of a cylindrical shell reinforced with ring ribs attached to the shell by means of elastic elements are studied.
The problem is solved by the finite-element method. The shell and ribs are modelled by a plane four-node finite element, which
is a combination of a four-node plane stress element and a four-node flexural element. The effect of the stiffness of the
elastic elements on the natural frequencies and modes is examined
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Translated from Prikladnaya Mekhanika, Vol. 41, No. 8, pp. 105–110, August 2005. 相似文献
2.
E. K. Ankyanets 《International Applied Mechanics》2005,41(10):1177-1181
The vibrations of a cylindrical shell reinforced with circular ribs attached to it by means of discrete elastic elements are
studied. The problem is solved by the finite-element method. The shell and ribs are modeled by a plane four-node finite element,
which is a combination of a four-node plane stress element and a four-node flexural element. The effect of the stiffness of
the elastic elements on the natural frequencies and modes is examined
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Translated from Prikladnaya Mekhanika, Vol. 41, No. 10, pp. 108–113, October 2005. 相似文献
3.
Christian Mittelstedt 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(7):439-452
The present contribution deals with the onset of local buckling of compressively loaded thin-walled beams with open I, C,
Z, T and L-cross-sections made of laminated composite materials. The method employs a discrete plate analysis approach in
the course of which each structural subelement of interest—which presently is the flange—of the thin-walled cross-section
is considered as a separate composite plate with elastic rotational restraints at those edges where an adjacent substructural
element is located. While in many investigations the lamination schemes of webs and flanges are considered to be purely orthotropic,
in the present paper the laminate layups are allowed to be of an arbitrary non-orthotropic nature, which also allows for the
analysis of laminates with inherent bending–torsion coupling. The analysis of the buckling loads of the flanges of thin-walled
composite beams is performed using the Ritz-method for which some especially adjusted displacement shape functions are employed.
For the case of pure orthotropy, a novel closed-form solution is described. The accuracy of the employed approaches is established
by comparison with accompanying finite element simulations of thin-walled composite beams. It is revealed that the presented
methodology is highly efficient in terms of computational effort and yet performs with satisfying accuracy, which makes it
very attractive for actual practical applications whenever the local stability behaviour of wide-flange thin-walled composite
beams is to be considered. 相似文献
4.
The convective instability of mechanical equilibrium of an inclined plane layer of fluid developing under the action of a
static gravity field and high-frequency vibration is studied. Configurations corresponding to four directions of the equilibrium
temperature gradient — vertical, longitudinal, horizontal, and transverse — are considered for an arbitrary orientation of
the vibration axis. The stability limits and the characteristics of the critical perturbations are determined.
Perm’. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 8–15, January–February,
1998.
This investigation was carried out with partial support form RSA-NASA (contract No. 920/18 — 5208/96). 相似文献
5.
A. M. Afsar N. M. L. Huq J. I. Song 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(4):401-412
This study presents an analytical solution to elastic field in a roller-guided panel of symmetric cross-ply laminated composite
material. The mixed boundary value two-dimensional plane stress elasticity problem is formulated in terms of a single displacement
potential function. This reduces the problem to the solution of a single fourth order partial differential equation of equilibrium
as the other equilibrium equation is satisfied automatically. The solution is obtained in terms of an infinite Fourier series.
To present some numerical results, a panel of glass/epoxy laminated composite is considered and different components of stress
and displacement at different sections of the panel are presented graphically. To justify the present analytical solution,
it is compared with the finite element solution obtained by using the commercial software ANSYS. It is found that the two
solutions agree well with each other. This ensures that the formulation developed in this study based on the displacement
potential approach can be used to obtain analytical solution of an elastic field in structural elements of laminated composite
under any mode of boundary conditions prescribed in terms of either stress, displacement or any combination of these. 相似文献
6.
The stability of an elastic plate and an elastic panel placed in a supersonic gas flow is studied in a nonlinear formulation.
The gas velocity vector is directed at a small angle to them. The critical velocity of the flow is determined for various
parameter values. The numerical results obtained are compared. 相似文献
7.
B. A. Lugovtsov 《Journal of Applied Mechanics and Technical Physics》1998,39(6):847-849
A plane analog of the problem of spontaneous swirling—the occurrence of a free transverse flow due to disturbance of the initial
plane-parallel flow—is considered. It is shown that in flows with circular streamlines between coaxial cylinders, loss of
stability can result in the occurrence of axial flow that is axisymmetric on the average (averaging over the axial coordinate
and the azimuthal angle) because of the countergradient transfer of the axial momentum component by Reynolds stresses.
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 6, pp. 33–36, November–December, 1998. 相似文献
8.
A. P. Pirentis K. A. Lazopoulos 《Archive of Applied Mechanics (Ingenieur Archiv)》2006,76(7-8):481-496
Stability studies of a T3 tensegrity structure are performed. This structure is composed of three slender struts interconnected by six nonlinear elastic tendons and is prestressed. The struts are governed by linear constitutive laws and are allowed to buckle. Since tensegrity is used for modeling structures with quite large deformations, for example the cytoskeleton, and bifurcation theory—valid for small solutions of the nonlinear equations—does not directly apply, a general procedure for studying the stability behavior of the particular tensegrity model based upon the elastica theory is presented. The reference placement is defined by the prestress, and the equilibrium placements are defined by the applied force and moment. 相似文献
9.
The limit equilibrium of elastoplastic body is studied under the conditions of a plane problem. The body contains a linear
inclusion, which is rigid but of finite rupture strength. The plastic or prefracture zones develop near the ends of the inclusion
and are modeled by slip cracks along the matrix—inclusion interface. A new interpretation of the boundary conditions is proposed
to solve a model problem for such a composition, and its analytical solution is derived. Two possible mechanisms of local
fracture are considered: (a) fracture of the inclusion and (b) separation of the inclusion. The critical length of the inclusion
is determined. This length together with the elastic and strength parameters of the composition determines the mechanism of
local fracture. The limit loads are found for each mechanism of fracture.
State Academy of Water Industry, Rovno, Ukraine. Translated from Prikladnaya Mekhanika, Vol. 36, No. 7, pp. 123–129, July,
2000. 相似文献
10.
We study the spectral stability of a family of periodic standing wave solutions to the generalized Korteweg–de Vries in a
neighborhood of the origin in the spectral plane using what amounts to a rigorous Whitham modulation theory calculation. In
particular we are interested in understanding the role played by the null directions of the linearized operator in the stability
of the traveling wave to perturbations of long wavelength. A study of the normal form of the characteristic polynomial of
the monodromy map (the periodic Evans function) in a neighborhood of the origin in the spectral plane leads to two different
instability indices. The first, an orientation index, counts modulo 2 the total number of periodic eigenvalues on the real
axis. This index is a generalization of the one which governs the stability of the solitary wave. The second, a modulational
instability index, provides a necessary and sufficient condition for the existence of a long-wavelength instability. This
index is essentially the quantity calculated by Hǎrǎguş and Kapitula in the small amplitude limit. Both of these quantities
can be expressed in terms of the map between the constants of integration for the ordinary differential equation defining
the traveling waves and the conserved quantities of the partial differential equation. These two indices together provide
a good deal of information about the spectrum of the linearized operator. We sketch the connection of this calculation to
a study of the linearized operator—in particular we perform a perturbation calculation in terms of the Floquet parameter.
This suggests a geometric interpretation attached to the vanishing of the orientation index previously mentioned. 相似文献
11.
The effect of a thin isotropic coating on the edge effect zone in a representative element of a coated material is examined.
Isotropic and transversely isotropic materials are considered. The transversely isotropic material has the elastic properties
of unidirectional glass-fiber-reinforced plastic. The decay of the edge effect in the directions perpendicular to the coating
plane and to the plane of isotropy is studied. A boundary-value problem of elasticity for piecewise-homogeneouse orthotropic
bodies and a quantitative edge effect decay criterion for normal stresses are used as a design model. The problem is solved
using the finite-difference method and base schemes. The results of evaluation of the edge effect zone in homogeneous and
inhomogeneous materials are presented. It is shown that the presence of a thin isotropic coating blocks the edge effect, that
is, decreases the edge effect zone in both isotropic and transversely isotropic materials
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Translated from Prikladnaya Mekhanika, Vol. 43, No. 12, pp. 61–67, December 2007. 相似文献
12.
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
13.
Green's function for incremental nonlinear elasticity: shear bands and boundary integral formulation
An elastic, incompressible, infinite body is considered subject to plane and homogeneous deformation. At a certain value of the loading, when the material is still in the elliptic range, an incremental concentrated line load is considered acting at an arbitrary location in the body and extending orthogonally to the plane of deformation. This plane strain problem is solved, so that a Green's function for incremental, nonlinear elastic deformation is obtained. This is used in two different ways: to quantify the decay rate of self-equilibrated loads in a homogeneously stretched elastic solid; and to give a boundary element formulation for incremental deformations superimposed upon a given homogeneous strain. The former result provides a perturbative approach to shear bands, which are shown to develop in the elliptic range, induced by self-equilibrated perturbations. The latter result lays the foundations for a rigorous approach to boundary element techniques in finite strain elasticity. 相似文献
14.
V. V. Kuznetsov S. V. Levyakov 《Journal of Applied Mechanics and Technical Physics》2007,48(5):755-765
A refined geometrically nonlinear formulation of a thin-shell finite element based on the Kirchhoff-Love hypotheses is considered.
Strain relations, which adequately describe the deformation of the element with finite bending of its middle surface, are
obtained by integrating the differential equation of a planar curve. For a triangular element with 15 degrees of freedom,
a cost-effective algorithm is developed for calculating the coefficients of the first and second variations of the strain
energy, which are used to formulate the conditions of equilibrium and stability of the discrete model of the shell. Accuracy
and convergence of the finite-element solutions are studied using test problems of nonlinear deformation of elastic plates
and shells.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 160–172, September–October, 2007. 相似文献
15.
The problem of the beginning of motion of a cut in a plane under symmetric external loading is considered. The material lying
on the cut continuation forms a layer (interaction layer). A transition to a plastic state within the layer is assumed to
be possible. The behavior of the layer is described by an ideally elastoplastic model, and the plane outside the layer is
assumed to be linearly elastic. A system of boundary integral equations for determining the stress-strain state is derived.
Based on this system, a discrete model of separation of the layer material is constructed under the assumption of a constant
stress-strain state in the element of the interaction layer. The distribution of stresses in the pre-fracture zone is determined.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 187–195, July–August, 2009 相似文献
16.
Du Xun 《Acta Mechanica Sinica》1987,3(4):297-303
The artificial viscosity method for three—dimensional unsteady gas flow is developed. The stability of finite difference scheme
in this case is investigated. The necessary and sufficient conditions for the stability are obtained; these conditions formally
agree with the two-dimensional result in Rusanov's paper. 相似文献
17.
The linearized theory of elasticity for prestressed bodies is used to solve a stationary plane problem for a prestressed two-layer
half-space under a surface load moving with constant velocity. The half-space is assumed to be compressible and to have an
arbitrary elastic potential. The Fourier transform is used to obtain the fundamental solution of the problem for different
contact conditions and load velocities. A compressible material with a harmonic elastic potential is considered as an example
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Translated from Prikladnaya Mekhanika, Vol. 44, No. 4, pp. 35–55, April 2008. 相似文献
18.
V. V. Vedeneev 《Fluid Dynamics》2004,39(4):526-533
The stability of an unbounded plane elastic plate in gas moving on one side of the plate and at rest on the other is analyzed. The gases are inviscid and in general different. The plate is under tension and has flexural stiffness. It is shown that the system is always unstable to plane sinusoidal perturbations with wave vector parallel to the velocity. As limiting cases, a tangential discontinuity between the two gases and unilateral flow past a plate with constant pressure on the opposite side are considered. In these cases, the conditions of stability to plane perturbations are non-trivial and are investigated below. 相似文献
19.
20.
V. I. Nosik 《Fluid Dynamics》1994,29(1):133-139
Nonequilibrium dissociation in a mixture of anharmonic oscillators — molecules of a diatomic gas and its atoms — is investigated
with allowance for the temperature gradient in the boundary layer. The effect of VT, VV, and VT′ exchanges on the dissociation
rate is considered, and the nonequilibrium correction to the macroscopic reaction rate, which depends, in particular, on the
temperature gradient and degree of dissociation, is determined.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.1, pp. 171–179, January–February,
1994. 相似文献