共查询到20条相似文献,搜索用时 343 毫秒
1.
V. M. Akhundov 《Mechanics of Composite Materials》2007,43(2):159-172
Equations for a round cylinder weakly reinforced with systems of yarns and subjected to large tensile, inflation, and torsional
deformations are presented. Since the degree of filling is small, the model of uniaxial stress state is assumed. The fibers
are aligned with spirals on cylindrical surfaces and with radii in the transverse and meridional sections of the cylinder.
The equations are obtained in the macroscopically unidimensional statement for the case of cylindrically symmetric strains.
Numerical results are given for twisted hollow rubber cylinders reinforced with polymer yarns in the axial and radial directions.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 2, pp. 237–256, March–April, 2007. 相似文献
2.
Zhi-Min Li 《Mechanics of Composite Materials》2007,43(6):535-560
A postbuckling analysis is presented for a shear-deformable anisotropic laminated cylindrical shell of finite length subjected
to external pressure in thermal environments. The material properties are expressed as linear functions of temperature. The
governing equations are based on Reddy’s higher-order shear-deformation shell theory with the von Karman-Donnell-type kinematic
nonlinearity. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into
account. The boundary-layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, large
deflections in the postbuckling region, and the initial geometric imperfections of the shell, is extended to the case of shear-deformable
anisotropic laminated cylindrical shells under lateral or hydrostatic pressure in thermal environments. The singular perturbation
technique is employed to determine the interactive buckling loads and postbuckling equilibrium paths. The results obtained
show that the variation in temperature, layer setting, and the geometric parameters of such shells have a significant influence
on their buckling load and postbuckling behavior.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 43, No. 6, pp. 789–822, November–December, 2007. 相似文献
3.
A. B. Mitkevich 《Mechanics of Composite Materials》2005,41(6):497-504
Errors in the programs of winding pressure vessels can lead to an asymmetric reinforcement structure, which affects the equilibrium
shape of their domes and the tension in the left and right families of filaments. In this paper, equations determining the
equilibrium shape of the domes, the tension in filaments, and the shear stresses between layers are obtained. Examples with
winding trajectories in the form of geodesics and constant-deviation lines are considered. It is found that, for pressure
vessels, in the absence of external torque, the tension levels in filaments of the left and right families differ considerably.
It is also revealed that, for actual friction coefficients in winding, the shear stresses taken up by the binder are insignificant.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 743–752, November–December, 2005. 相似文献
4.
The nonlinear buckling behavior of a 3D-braided composite cylindrical shell of finite length subjected to internal pressure
in thermal environments is considered. According to a new micromacromechanical model, a 3D-braided composite may be treated
as a cell system where the geometry of each cell strongly depends on its position in the cross section of the cylindrical
shell. The material properties of the epoxy matrix are expressed as linear functions of temperature. The governing equations
are based on Reddy’s higher-order shear deformation theory of shells with a von Karman–Donnell-type kinematic nonlinearity
and include thermal effects. The singular perturbation technique is employed to determine the buckling pressure and the postbuckling
equilibrium paths of the shell. 相似文献
5.
The problem on the elastoplastic deformation of reinforced shells of variable thickness under thermal and force loadings is
formulated. A qualitative analysis of the problem is carried out and its linearization is indicated. Calculations of isotropic
and metal composite cylindrical shells have shown that the load-carrying capacity of shell structures under elastoplastic
deformations is several times (sometimes by an order of magnitude) higher than under purely elastic ones; the heating of shells
with certain patterns of reinforcement sharply reduces their resistance to elastic deformations, but only slightly affects
their resistance to elastoplastic ones; not always does the reinforcement in the directions of principal stresses and strains
provide the greatest load-carrying capacity of a shell; there are reinforcement schemes that ensure practically the same resistance
of shells at different types of their fastening.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 6, pp. 707–728, November–December, 2006. 相似文献
6.
V. F. Chekurin 《Journal of Mathematical Sciences》2000,99(5):1692-1698
We considered the inverse problem of determination of the stress-strain state of a circular cylindrical shell that consists
of two heterogeneous parts joined by a circular seam. As the input data for this problem, the results of polarization-optical
measurements are used. The problem is formulated within the framework of a model that considers residual stress as caused
by the geometric incompatibility of elastic deformations.
Pidstryhach Institute of Applied Problems in Mechanics and Mathematics, Ukrainian Academy of Sciences, L'viv. Translated from
Matematychni Metody ta Fizyko-Mekhanichni Polya, Vol. 41, No. 2, pp. 151–156, April–June, 1998. 相似文献
7.
On the basis of the variational method we discuss an approach to the computation of the stress-strain state of a conical shell
made of a composite material and weakened by a hole. For a glass-plastic shell with a round unreinforced hole we study the
influence of the variation of an interlayer shear and orthotropy on the stress concentration. Two tables. Bibliography: 4
titles.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 22, pp. 63–67, 1991. 相似文献
8.
基于Reddy高阶剪切变形理论的Kármám-Donnell型非线性壳体方程,给出复合材料层合剪切圆柱曲板在侧压作用下的后屈曲分析。将壳体屈曲的边界层理论推广到复合材料层合剪切圆柱曲板受侧压作用的情况。相应的奇异摄动法,用于确定圆柱曲板的屈曲荷载和后屈曲平衡路径。分析中同时考虑非线性前屈曲变形和初始几何缺陷的影响。数值算例给出完善和非完善,中等厚度正交铺设层合圆柱曲板的后屈曲荷载-挠度曲线。讨论了横向剪切变形,曲板几何参数,铺层数,铺展方式和初始几何缺陷等各种参数变化的影响。 相似文献
9.
The stress-strain state of multilayered plates on an undeformable foundation is investigated. The design diagram of a transversely
loaded plate is formed by supplementing it with a symmetric one about the contact surface of the foundation. The double-thickness
plate obtained becomes loaded bilaterally and symmetrically about its midsurface. In such a way, only unflexural deformations
can be modeled, which reduces the number of unknowns and the general order of differentiation of the resolving system of equations.
The refined continual model developed takes into account the deformations of transverse shear and transverse compression in
high iterative approximations. The cases of a rigid contact between the foundation and the plate and frictionless slip of
the plate over the foundation are considered. Calculations confirm the efficiency of such an approach, which allows one to
obtain solutions qualitatively and quantitatively close to three-dimensional ones.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 5, pp. 643–654, September–October, 2006. 相似文献
10.
The deformation behavior of a 4D composite reinforced along cube diagonals under large shear deformations is examined. The investigation is based on an applied theory which allows one to perform a macromechanical analysis of composite materials with small volume contents of reinforcing yarns to an accuracy sufficient in practice. Qualitative differences between the properties of such composites under large and small shear deformations are revealed. The evolution of the structural geometry of the deformed composite material is traced. 相似文献
11.
M. H. B. M. Shariff 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,56(4):1112-1134
A general constitutive theory for anisotropic stress softening in compressible solids is presented. The constitutive equation
describes anisotropic strain induced behaviour of an initially “isotropic” virgin material. Parameters which characterise
damage are proposed together with a concept of damage function. In order to develop an anisotropic stress-softening theory
for compressible materials in close parallel to a recent incompressible anisotropic theory, the right stretch tensor is decomposed
into its isochoric and dilatational parts. The ’free’ energy is expressed as a function of the dilatation, modified principal
stretches, a volume change parameter and invariants of the dyadic products of the principal directions of the right stretch
tensor and two structural tensors. A class of free energy functions is discussed and a special form of this class which satisfies
the Clausius–Duhem inequality is proposed. Results of the theory applied to uniaxial tension, bulk compression and simple
shear deformations are given. A sequence of deformations involving shear, hydrostatic-compression and hydrostatic-tension
deformations is also investigated. In the case of hydrostatic-tension deformation, the stress softening is due to cavitation
damage. The theoretical results obtained are consistent with expected behaviour and compare well with experimental data. 相似文献
12.
Based on the discrete-structural theory of thin plates and shells, a calculation model for thin-walled elements consisting
of a number of rigid anisotropic layers is put forward. It is assumed that the transverse shear and compression stresses are
equal on the interfaces. Elastic slippage is allowed over the interfaces between adjacent layers. The solution to the problem
is obtained in a geometrically nonlinear statement with account of the influence of transverse shear and compression strains.
The stress-strain state of circular two-layer transversely isotropic plates, both without defects and with a local area of
adhesion failure at their center, is investigated numerically and experimentally. It is found that the kinematic and static
contact conditions on the interfaces of layered thin-walled structural members greatly affect the magnitude of stresses and
strains. With the use of three variants of calculation models, in the cases of perfect and weakened contact conditions between
layers, the calculation results for circular plates are compared. It is revealed that the variant suggested in this paper
adequately reflects the behavior of layered thin-walled structural elements under large deformations.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 761–772, November–December, 2005. 相似文献
13.
A mathematical model of superposition of large butt-end and coaxial torsional and axial shear deformations of homogeneous
and fiber-reinforced thick-wall cylinders is constructed. The macroscopic stresses of the reinforced material are additively
determined by matrix stresses and by tensile or constrained compression stresses in the reinforcing fibers. The model is based
on the numerical solution of two boundary-value problems, one of which corresponds to the butt-end torsion and the other to
the coaxial torsion and axial shear. The boundary-value problem on joint deformations is solved with the use of the displacement
field determined from the solution to the boundary-value problem on butt-end torsion. The results obtained by applying this
method to homogeneous and axially-radially reinforced thick-wall cylinders subjected to butt-end torsion with subsequent coaxial
torsion and axial shear are presented.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 4, pp. 465–492, July–August, 2007. 相似文献
14.
Behavior of concrete cylinders confined by carbon-composite tapes and prestressed yarns 1. Experimental data 总被引:1,自引:0,他引:1
V. Tamuzs R. Tepfers Chi-Sang You T. Rousakis I. Repelis V. Skruls U. Vilks 《Mechanics of Composite Materials》2006,42(1):13-32
The results of a comprehensive test program for the mechanical behavior of round concrete specimens confined by carbon-fiber
epoxy tapes and prestressed carbon yarns are reported. Five different concrete batches of compressive strength from 20 to
100 MPa and the confinement of various thickness and pretension level were investigated. The specimens, which were subjected
to monotonic or repeated compressive loadings, showed a nonlinear stress-strain behavior with a significant ductility and
increased ultimate strength, in contrary to the brittle behavior of plain concrete. The limit of linearity on the stress-strain
diagrams of the confined concrete roughly coincided with the ultimate strength of plain concrete. Above this limit, the damage
accumulation and plastic deformations proceeded in the confined specimens. This fact was evidenced by the increasing slope
of deformation diagrams in unloadings and repeated loadings and by the pronounced residual strains. The limit of linearity
could be raised significantly by pretension of the carbon yarns during their winding.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 1, pp. 21–44, January–February, 2006. 相似文献
15.
V. V. Porokhovs’kyi 《Journal of Mathematical Sciences》2009,160(4):443-452
We have proposed a procedure for investigating the stressed state of a thin-walled round cylindrical shell with a cut along
its generatrix, which is placed into an elastic space. A longitudinal elastic wave is incident on the shell. The procedure
is based on the use of the Rayleigh expansion in partial waves. We have obtained relations for determining the displacement
jumps and angle of rotation at the lips of the shell cut, the radial component of the displacement vector and the normal force
in the cylindrical shell, as well as the stresses and displacements in the elastic medium.
Translated from Matematychni Metody ta Fizyko-Mekhanichni Polya, Vol. 51, No. 1, pp. 131–137, January–March, 2008. 相似文献
16.
R. Yu. Amenzadeh G. Yu. Mekhtiyeva L. F. Fatullayeva 《Mechanics of Composite Materials》2011,46(6):649-658
The buckling of a long multilayered nonlinearly elastic shell made of different materials and subject to the action of external
pressure is investigated. The load is not hydrostatic and greatly varies in value and direction. Neglecting the effect of
end fastening of the shell, the problem is reduced to an analysis of the loss of load-carrying ability of a ring of unit width
separated from the shell. The solution is based on a variational method of mixed type formulated for heterogeneous nonlinearly
elastic bodies, taking into account the geometrical nonlinearity, in a combination with the Rayleigh–Ritz method. The initial
analysis is reduced to solving the Cauchy problem for a nonlinear ordinary differential equation resolved for the derivative.
Numerically, using the Runge–Kutta method, the effect of the number of layers and of the parameter of nonuniformity of the
external pressure on the critical buckling force is revealed. The urgency and importance of the problem are connected with
the research of reserves in the saving of materials with a simultaneous possibility of increasing the load-carrying ability
of a structure. 相似文献
17.
V. Siryus 《Mechanics of Composite Materials》2011,46(6):593-598
The minimization of the weight of ribbed viscoelastic composite cylindrical shells under a long-term external pressure is
considered. The shells are strengthened with six inner stiffening rings with identical geometric parameters and a square cross
section. It is assumed that the shell material obeys the linear law of hereditary creep and the displacements across the shell
wall are distributed according to the Timoshenko hypothesis. The shell must withstand an external pressure of –0.5 MPa without
the loss of stability for an unlimited time. The parameters of optimization are the intensity of reinforcement and thickness
of its covering and the height and width of the stiffening rings. It is found that the weight of an optimum ribbed shell is
24% lower than that of an optimum cylindrical shell without ribs. 相似文献
18.
E. U. Dadamukhamedov V. A. Maksimyuk I. S. Chernyshenko 《Journal of Mathematical Sciences》1995,74(4):1170-1172
We propose a method of experimental estimation of the influence of the stiffness of elements that reinforce the contour of
a hole on the deformed state of shells under surface pressure. We obtain the experimental data for the deflections on the
contour of a lateral hole in a cylindrical shell as a function of the stiffness characteristics and the caps. We compare the
results of experiments with numerical computations and give an analysis of the theoretical and experimental data obtained.
Three figures. Bibliography: 5 titles.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 22, pp. 67–71, 1991. 相似文献
19.
D. Srinivasacharya 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2007,58(4):646-658
In this paper, the creeping flow of an incompressible viscous liquid past a porous approximate spherical shell is considered.
The flow in the free fluid region outside the shell and in the cavity region of the shell is governed by the Navier–Stokes
equation. The flow within the porous annulus region of the shell is governed by Darcy’s Law. The boundary conditions used
at the interface are continuity of the normal velocity, continuity of the pressure and Beavers and Joseph slip condition.
An exact solution for the problem is obtained. An expression for the drag on the porous approximate spherical shell is obtained.
The drag experienced by the shell is evaluated numerically for several values of the parameters governing the flow. 相似文献
20.
D. Srinivasacharya 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2007,52(3):646-658
In this paper, the creeping flow of an incompressible viscous liquid past a porous approximate spherical shell is considered.
The flow in the free fluid region outside the shell and in the cavity region of the shell is governed by the Navier–Stokes
equation. The flow within the porous annulus region of the shell is governed by Darcy’s Law. The boundary conditions used
at the interface are continuity of the normal velocity, continuity of the pressure and Beavers and Joseph slip condition.
An exact solution for the problem is obtained. An expression for the drag on the porous approximate spherical shell is obtained.
The drag experienced by the shell is evaluated numerically for several values of the parameters governing the flow. 相似文献