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1.
R. D. Maksimov S. Gaidukovs J. Zicans M. Kalnins E. Plume V. Spacek P. Sviglerova 《Mechanics of Composite Materials》2006,42(4):353-362
The results of an investigation into the barrier and thermal properties of polymer nanocomposites prepared by blending a styrene-acrylate
copolymer solution with a suspension of organically modified montmorillonite are presented. The influence of organomontmorillonite
content on the barrier properties of the nanocomposite is investigated with the example of water vapor permeability. The experimental
values of the permeability coefficient are compared with those calculated by using a model taking into account the increased
path of diffusing water molecules caused by the shielding effect of plate like particles. The thermograms of differential
scanning calorimetry in the temperature range from −40 to 130°C are presented. The results of a thermogravimetric analysis
for specimens heated in air to 800°C are also reported.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 4, pp. 503–516, July–August, 2006. 相似文献
2.
R. D. Maksimov S. Gaidukovs M. Kalnins J. Zicans E. Plume 《Mechanics of Composite Materials》2006,42(2):163-172
A variant of stepwise determination of the elastic characteristics of quasi-isotropic polymer-silicate nanocomposites with
randomly oriented platelike filler particles is considered. First, the elastic constants of transversely isotropic structural
elements with coplanarly placed filler particles are obtained, and then they are averaged over all spatial directions by using
the orientational averaging method. The characteristic features of the hierarchical structure of exfoliated and intercalated
nanocomposites are also considered. The concentration dependences of elastic constants of a nanocomposite based on a styrene-acrylate
copolymer and native montmorillonite clay are modeled, and the results obtained are compared with experimental data.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 235–246, March–April, 2006. 相似文献
3.
N. Lilichenko R. D. Maksimov J. Zicans R. Merijs Meri E. Plume 《Mechanics of Composite Materials》2008,44(1):45-56
The preparation of an environmentally friendly nanocomposite based on plasticized potato starch and unmodified montmorillonite
clay is described. Data on the influence of montmorillonite concentration on the mechanical properties of the materials obtained
are reported. The effective elastic constants of the nanocomposites are calculated. The calculation results are compared with
experimental data. The influence of montmorillonite content on the moisture permeability is also investigated.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 1, pp. 61–76, January–February, 2008. 相似文献
4.
A variant of determining the elastic characteristics of composites containing irregularly oriented shape-anisotropic filler
particles of two types (short fibers and thin platelets) is considered. The effective elastic constants of the composites
are calculated by using the method of orientational averaging of elastic characteristics of isolated transversely isotropic
structural elements reinforced with unidirectionally oriented short fibers or coplanarly arranged thin platelets. The superposition
of elastic properties of the irregularly oriented structural elements, with account of their orientational distribution in
the composite material, is accepted. The calculation results are compared with experimental data for the effective elastic
moduli of polymeric composites reinforced with short glass fibers and of polymeric nanocomposites containing the platelet-type
particles of organically modified montmorillonite.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 285–300, May–June, 2006. 相似文献
5.
Within the framework of fractal analysis and percolation theory, an alternative model of reinforcement of filled polymers
is offered. Practically, this model can be used only to describe the reinforcement of nanocomposites, because, according to
the treatment considered, a pronounced reinforcement can be reached only at ratios of filler particle diameter to the statistical
segment length of about 10 and less. A theoretical calculation showed a good qualitative and quantitative agreement with experiments.
The type of reinforcement mechanism of composites is determined by the type of the space (fractal or Euclidean) in which the
structure of the polymeric matrix is formed.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 6, pp. 797–802, November–Decem ber, 2006. 相似文献
6.
E. A. Aliyev 《Mechanics of Composite Materials》2007,43(6):521-534
Within the framework of a piecewise homogenous body model and with the use of a three-dimensional linearized theory of stability
(TLTS), the local near-surface buckling of a material system consisting of a viscoelastic (elastic) half-plane, an elastic
(viscoelastic) bond layer, and a viscoelastic (elastic) covering layer is investigated. A plane-strain state is considered,
and it is assumed that the near-surface buckling instability is caused by the evolution of a local initial curving (imperfection)
of the elastic layer with time or with an external compressive force at fixed instants of time. The equations of TLTS are
obtained from the three-dimensional geometrically nonlinear equations of the theory of viscoelasticity by using the boundary-form
perturbation technique. A method for solving the problems considered by employing the Laplace and Fourier transformations
is developed. It is supposed that the aforementioned elastic layer has an insignificant initial local imperfection, and the
stability is lost if this imperfection starts to grow infinitely. Numerical results on the critical compressive force and
the critical time are presented. The influence of rheological parameters of the viscoelastic materials on the critical time
is investigated. The viscoelasticity of the materials is described by the Rabotnov fractional-exponential operator.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 43, No. 6, pp. 771–788, November–December, 2007. 相似文献
7.
The elastic deformation behavior and the load-carrying capacity of unidirectional carbon fiber laminates under static loading
at room and cryogenic (down to 77 K) temperatures are investigated. The possible ways of predicting their elastic and strength
characteristics proceeding from the volume content and mechanical parameters of fibers and matrix are analyzed.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 5, pp. 583–598, September–October, 2006. 相似文献
8.
D. Pizele V. Kalkis R. Merijs Meri T. Ivanova J. Zicans 《Mechanics of Composite Materials》2008,44(2):191-196
Blends of low-density polyethylene (LDPE) and ethylene-octene copolymer (EOC) were obtained. The effect of EOC content and
absorbed radiation dose on the mechanical and thermomechanical properties of LDPE/EOC blends are investigated. Particular
attention is given to a tensile stress-strain analysis and the “form-memory” effect of the blends. With growing LDPE content,
the elastic modulus, the yield stress, and the thermorelaxation and residual stresses of the blends increase, but the ultimate
elongation at break decreases, which is caused by the higher crystallinity of polyethylene. As a result of radiation-induced
cross-linking, the elastic modulus, the yield stress (at a 1% strain), the ultimate yield strength, and the thermorelaxation
and residual stresses increase, while the ultimate elongation at break and the melt flow-behavior index decrease, which is
confirmed by the growing gel fraction in the blend.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 2, pp. 279–286, March–April, 2008. 相似文献
9.
Analysis results for the elastic properties of a composite with a small amount of coplanarly arranged platelike filler particles
are presented. The geometrical form of the particles is described by an oblate ellipsoid of revolution. The calculations are
performed by formulas obtained by using the Eshelby approach for media with a low concentration of inclusions. The effect
of anisometry of the ellipsoidal particles and of the ratio between the elastic moduli of the filler and matrix on the effective
elastic constants of the composite is discussed. Calculation results are compared with experimental data for the elastic moduli
of a nanocomposite containing completely exfoliated particles of an unmodified montmorillonite.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 4, pp. 493–504, July–August, 2008. 相似文献
10.
The influence of the content of carbon nanofillers (multi-and single-wall nanotubes) on the thermophysical properties of epoxy
nanocomposites was investigated on the temperature range from −150 to 150°C. A “plateau” was found to exist in the concentration
dependence of thermal conductivity on the concentration interval from 0.1 to 1.0 wt.% carbon nanotubes (CNTs). The thermal
conductivity of the CNT composites exceeded that of pure epoxy resin by about 40%. A further increase in CNT content de creased
the conductivity, owing to increasing interfaces between the two phases and the additional thermal resistance caused by phonon
scattering on them. It is found that the temperature interval of transition of the composite from a glassy to a viscoelastic
state greatly depends on the filler type and concentration. There exists a critical concentration at which a drop in the glass-transition
temperature by 30% can be observed. The reason is the undercure of binder as a result of interaction between CNTs and epoxy
macromolecules, which reduces the cross-linking density of structure of the polymer.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 5, pp. 697–708, September–October, 2008. 相似文献
11.
The stability of elastic columns subjected to axial pressure is studied. An elastic multistepped column with rectangular cross
sections are considered assuming that at the re-entrant corners of the column stable cracks are located. The influence of
a crack on the loss of stability of the column is described by means of local flexibility and the function of compliance coupled
with the stress intensity factor, which is known from the linear elastic fracture mechanics. A column with a single step is
studied in more detail. The influence of crack location and length on the buckling load is assessed numerically.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 1, pp. 87–100, January–February, 2006. 相似文献
12.
S. B. Sapozhnikov A. N. Aniskevich V. A. Tsarevskii 《Mechanics of Composite Materials》2006,42(6):571-576
A numerical method for predicting the deformational and strength characteristics of a calcite-quartzitic polymer concrete
from the known properties of its components is developed based on the finite-element method. Components of the material are
assumed elastic and isotropic, and the filler particles are modeled by round inclusions perfectly bonded to the polymer matrix.
The size distribution of the inclusions correspond to that of actual fillers. The destruction process of the components is
simulated by sequentially excluding the particles in which the maximum principal stress has achieved the ultimate value for
this component. A comparison of calculated and experimental characteristics of the polymer concrete showed errors of 2–4%
for the elastic modulus and about 10% for the ultimate strength if the finite-element cell included not less than 20–30 average-size
particles and 2–5 large ones.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 6, pp. 817–824, November–December, 2006 相似文献
13.
Sodium fluorohectorite (FH) was incorporated into polystyrene (PS) in amounts of 4.5 and 7 wt.% by melt mixing, with and without
latex precompounding. The latex precompounding was used for the latex-mediated predispersion of FH particles. The related
masterbatch was produced by mixing PS latex with the water-swellable FH, followed by drying. The dispersion of FH in PS was
studied by transmission-, scanning electron-, and atomic force microscopy techniques (TEM, SEM, and AFM, respectively). The
stress relaxation in the PS composites was determined in short-term isothermal tests. The latter were performed at various
temperatures between 25 and 75°C. The direct melt mixing of FH with PS resulted in microcomposites, whereas the masterbatch
technique gave rise to nanocomposites. The master curves (relaxation modulus vs. time), constructed by applying the time-temperature
superposition principle (TTSP), showed that the Williams-Landel-Ferry (WLF) equation, the Maxwell model, and the Findley power
law were fairly applicable to the experimental results obtained.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 5, pp. 709–722, September–October, 2008. 相似文献
14.
R. D. Maksimov S. Gaidukov J. Zicans J. Jansons 《Mechanics of Composite Materials》2008,44(5):505-514
Results of an investigation into the kinetics of moisture sorption by an unfilled styrene-acrylate copolymer and a nanocomposite
containing unmodified montmorillonite clay are reported. The sorption tests were performed at 25°C and different levels of
the relative humidity of air up to 80%. The moisture diffusivity was calculated using Fick's equation for one-dimensional
diffusion. Data on the influence of montmorillonite concentration on the coefficients of diffusion, solubility, and permeability
are obtained. The experimental values of the permeability coefficient are compared with those calculated by using a model
taking into account the increased path of a diffusing water molecule caused by the shielding effect of plate like filler particles.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 5, pp. 723–736, September–October, 2008. 相似文献
15.
The study aims to predict the elastic and damping properties of composite laminated plates from measured dynamical characteristics.
The elastic constants and damping properties of a laminated element are determined by using experimental data and the results
of a multilevel theoretical approach. Solution examples for particular problems are given.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 1, pp. 35–50, January–February, 2008. 相似文献
16.
R. Merijs Meri T. Bocoka J. Zicans M. Kalnins V. Kalkis A. K. Bledzki 《Mechanics of Composite Materials》2008,44(4):361-370
Changes in the toughness of crystalline poly(ethylene terephtalate) upon addition of two elastomers — ethylene-propylene-diene
terpolymer and ethylene-α-octene copolymer — are investigated. Blends with increasing elastomer content (up to 30 wt.%) were obtained and modified
by γ-radiation up to a 300-kGy absorbed dose. The interrelation between the toughness and certain tensile characteristics (elastic
modulus, yield stress, ultimate stress, elongation at break, and specific fracture energy) of the blends, with various structural
features of components (crystallinity and the degree of cross-linking) and morphology of the blends, is discussed.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 4, pp. 521–534, July–August, 2008. 相似文献
17.
Description of the elastic deformation and degradation of elastic properties of dispersedly failing isotropic materials 总被引:1,自引:1,他引:0
A model is put forward for describing the elastic deformation of a quasi-homogeneous isotropic material capable of accumulating
scattered microdamages during loading, which eventually leads to its total failure. The degree of damage of the material at
a point is characterized by a centrosymmetric scalar function on the unit sphere, named the damage function, whose values
depend on a dimensionless equivalent stress. This function is approximated by a fourth-rank tensor, which is used to construct
a constitutive relation between stresses and strains in a differential form. By way of example, the elastic deformation of
concrete and the degradation of its linearly elastic properties are described, and the basic three-dimensional sections of
the corresponding strength surface are constructed.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 193–208, March–April, 2006. 相似文献
18.
Bending of an elastic annular composite plate with a light filler lying on an elastic foundation is considered. The plate
is subjected to local loads. To describe the kinematics of the package, asymmetric across its thickness, the hypotheses of
broken normal is accepted. The reaction of foundation is described based on the Winkler model. A system of equilibrium equations
is constructed, and its exact solution in displacements is found. Numerical solutions for a metal-polymer sandwich plate are
presented.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 1, pp. 109–120, January–February, 2007. 相似文献
19.
R. M. Martynyak B. S. Slobodyan V. M. Zelenyak 《Journal of Mathematical Sciences》2009,160(4):470-477
A model of contact between an elastic half space and a rigid base with a shallow surface rectangular hole is proposed. The
hole contains an incompressible liquid and gas. The liquid occupies the middle part of the hole and forms a capillary bridge
between the opposite surfaces. The remaining volume of the hole is filled with gas under a constant pressure. The liquid completely
wets the surfaces of the bodies. The pressure drop at the liquid–gas interface caused by the surface tension is defined by
the Laplace formula. The corresponding plane contact problem for the elastic half space is essentially nonlinear because the
pressure of the liquid and the length of the capillary in the contact-boundary conditions are not known in advance and depend
on the external load. The problem is reduced to a system of three equations (a singular integral equation for the function
of height of the hole and two transcendental equations for the length of the capillary and the height of the meniscus). An
analytic-numerical procedure for the solution of these equations is proposed. Dependences of the length of the capillary and
the pressure drop at the liquid–gas interface on the external load, volume of liquid, and its surface tension are analyzed.
Translated from Matematychni Metody ta Fizyko-Mekhanichni Polya, Vol. 51, No. 1, pp. 150–156, January–March, 2008. 相似文献
20.
Nano-zinc sulfide (ZnS)- and nano-titanium dioxide (TiO2)-reinforced polyetheretherketone (PEEK) composites for use under extreme mechanical and tribological loads were developed
and investigated systematically. The nanocomposites were manufactured with particle concentrations of 1 to 15 vol.% by using
an optimized twin-screw extrud er technology. A simultaneous increase in the strength and elastic modulus of PEEK and an improvement
in the tribological properties of PEEK/ZnS compounds were observed. Also, the specific wear rate decreased with increasing
ZnS content, reaching its minimum at 3 vol.%. This minimum corresponded to a 60% reduction in the wear rate com pared with
that of the neat PEEK. A wear map was re corded for the 3 vol.% composite, which depicted the in fluence of the sliding speed
and the normal force on the wear rate over a wide range of parameters.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 45, No. 2, pp. 289-298, March-April, 2009. 相似文献