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1.
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
2.
The plane problem of three-dimensional stability is solved for a transversely compressed composite material reinforced with
ribbons taking into account the inhomogeneous initial state. An approximate solution of the problems is based on the net method.
The effect of the ribbon form factor, the ratio between the elastic moduli of the matrix and filler, and Poisson ratio of
the filler on the critical deformation of the material is investigated.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 1, pp. 77–86, January–February, 2000. 相似文献
3.
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
4.
A variant of a stepwise analysis of the elastic properties of a carbon-nanotube-reinforced composite with account of the effect
of interphase layers between the nanotubes and the polymer matrix is reported. The preliminary calculation of the elastic
constants of a structural element incorporating a nanotube and an interphase layer and the subsequent calculation of independent
elastic constants of a composite with such transversely isotropic structural elements oriented in one direction are both performed
by using the Mori–Tanaka theory of an equivalent medium. The calculations are carried out for a wide range of ratios between
the elastic moduli of the interphase layer and matrix. The elastic constants of a composite with randomly oriented nanotubes
are obtained by using the method of orientational averaging. 相似文献
5.
D. D. Zakharov 《Mechanics of Composite Materials》1999,35(5):403-408
An asymptotic analysis of the dynamic stress-strain state of a thin laminar packet of anisotropic layers is presented. The
statement is nonclassical, since in layer materials the ratio of elastic moduli in the longitudinal and transverse directions
can generate small parameters comparable to the relative half-thickness of the packet, as, for example, in high-strength unidirectional
composites. Alternation of strong load-carrying layers and a relatively soft filler with a similar difference in the elastic
moduli between the layers is also allowed. The averaged two-dimensional equations and the total stress tensor in the layers
are determined. The results are classified with respect to the types of anisotropy and the indices of differences in the elastic
moduli. It is shown that first-approximation models lead to kinematic relations similar to those of the theories of high-order
shear strains.
Institute of Problems of Mechanics, Russian Academy of Sciences, Moscow, Russia. Translated from Mekhanika Kompozitnykh Materialov,
Vol. 35, No. 5, pp. 605–614, September–October, 1999. 相似文献
6.
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
7.
The identification of elastic properties of laminated composite plates from measured eigenfrequencies has been performed.
The elastic moduli of the laminates were determined by using a multilevel modeling and a two-step identification procedure.
At the first step, based on a genetic algorithm, the Young’s and shear moduli were found, but at the second one, by minimizing
an error function, the values of transverse moduli were refined.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 2, pp. 207–216, March–April, 2008. 相似文献
8.
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
9.
Based on a plane model of composites, the effect of a transition layer on the elastic modulus Ec of the composites is analyzed in the case where, under the action of a load, the transition layer is formed both on the side
of matrix and filler. In evaluating Ec, it is assumed that the elastic modulus in the layer grows linearly from the elastic modulus of matrix to that of filler,
but pores in the filler are impermeable to matrix macromolecules. Analytic relation ships are found which allow one to determine
the volume fractions of the transition layer on the side of matrix and filler if the experimental elastic modulus of the composite
is known. These relationships are used to find the magnitude of the layer in epoxy composites with various fillers and to
evaluate its effect on the compressive elastic modulus of the composites.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 5, pp. 693–700, September–October, 2006. 相似文献
10.
L. Nazarenko L. P. Khoroshun W. H. Müller B. R. Wille 《Mechanics of Composite Materials》2009,45(1):11-20
A model of deformation of stochastic composites subjected to microdamage is developed for the case of orthotropic materials
with microdamages accumulating in the fibers. The composite is treated as a matrix strengthened with elliptic fibers with
orthotropic elastic properties. The fractured microvolumes are modeled by a system of randomly distributed quasi-spherical
pores. The porosity balance equation and relations for determining the effective elastic moduli for the case of a fibrous
composite with orthotropic components are used as the fundamental relations. The fracture criterion is given as a limit value
of the intensity of average shear stresses occurring in the undamaged part of the material, which is assumed to be a random
function of coordinates and is described by the Weibull distribution. Based on an analytical and numerical approach, the algorithm
for determining the nonlinear deformation properties of such a material is constructed. The nonlinearity of composite deformations
is caused by the accumulation of microdamages in the fibers. By using a numerical solution, the nonlinear stress–strain diagrams
for an orthotropic composite in uniaxial tension are obtained.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 45, No. 1, pp. 17–30, January–February, 2009. 相似文献
11.
The main focus of the present paper is the estimation of the macroscopic stress–strain behavior of a particulate composite.
A composite with a cross-linked polymer matrix in a rubbery state filled with an alumina-based mineral filler is investigated
by means of the finite-element method. The hyperelastic material behavior of the matrix is described by the Mooney–Rivlin
material model. Numerical models on the basis of unit cells are developed. The existence of a discontinuity (breaking) in
the matrix at higher loading levels is taken into account to obtain a more accurate estimate for the stress–strain behavior
of the particulate composite investigated. The numerical results obtained are compared with an experimental stress–strain
curve, and a good agreement is found to exist. The paper can contribute to a better understanding of the behavior and failure
of particulate composites with a polymer matrix. 相似文献
12.
The effects of orientation and shape of filler particles on the elastic properties of composites have been analyzed. The elastic
constants of a composite with irregularly oriented filler particles were calculated by using the method of orientational averaging
of the properties of a representative structural element. The elastic constants of the structural element were found according
to a known generalized Eshelby solution for a finite concentration of ellipsoidal inclusions. The diagrams of elasticity anisotropy
for a transversely isotropic structural element and an orthotropic composite with irregularly oriented inclusions are presented.
A quantitative estimate for the degree of anisotropy of elastic properties of composites is suggested. Data on the influence
of shape anisometry of inclusions on the anisotropy coefficient of filled composites are also reported. 相似文献
13.
L. V. Nazarenko 《Journal of Mathematical Sciences》2009,160(4):429-442
In the present paper, a model of deformation of stochastic composites under microdamaging is developed for the case of orthotropic
composite, when the microdamages are accumulated in the matrix. The composite is treated as an isotropic matrix strengthened
by three-axial ellipsoidal inclusions with orthotropic symmetry of elastic properties. It is assumed that the loading process
leads to accumulation of damages in the matrix. Fractured microvolumes are modeled by a system of randomly distributed quasispherical
pores. The porosity balance equation and relations for determining the effective elastic moduli for the case of a composite
with orthotropic components are taken as the basic relations. The fracture criterion is assumed to be given as the limit value
of the intensity of average shear stresses occurring in the undamaged part of the material. Based on the analytical and numerical
approach, an algorithm for the determination of nonlinear deformation properties of such a material is constructed. The nonlinearity
of composite deformations is caused by the accumulation of microdamages in the matrix. Using the numerical solution, nonlinear
stress-strain diagrams for the orthotropic composite in the case of biaxial extension are obtained.
Published in Matematychni Metody ta Fizyko-Mekhanichni Polya, Vol. 51, No. 1, pp. 121–130, January–March, 2008. 相似文献
14.
L. A. Golotina L. L. Kozhevnikova T. B. Koshkina 《Mechanics of Composite Materials》2008,44(6):633-640
Composites with an elastomeric matrix containing rigid particles of diameter 10–1000 μm are studied. One of possible mechanisms
of the rheological behavior of such filled systems, related to the origination and growth of vacuoles near the rigid inclusions
in a viscous matrix, is considered. For simulating the mechanism of formation of rheological properties of the filled elastomers,
we use a structural cell in the form of an elastomeric cylinder, whose height and diameter are equal in magnitude, with a
rigid spherical inclusion at its center. Deformation of the cells is examined with the observance of boundary conditions providing
the preservation of their close packing. The inclusion is assumed to be rigid, and the matrix properties are described by
equations of the linear hereditary viscoelasticity theory. The formation of vacuoles is described by using the approach suggesting
that an initial debonding begins to propagate when the energy accumulated in the extended matrix reaches a value sufficient
to create a new interface. The heterogeneity of the composite is simulated by taking into account the variability of the local
filler concentration. Creep curves obtained for composite cells with different content of the solid phase are presented. Comparisons
between the numerical and experimental results show a satisfactory agreement.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 6, pp. 895–906, November–December, 2008. 相似文献
15.
F. Qi N. Phan-Thien X. J. Fan 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2001,26(4):1-17
To efficiently calculate the effective properties of a composite, which consists of rigid spherical inclusions not necessarily of the same sizes in a homogeneous isotropic elastic matrix, a method based on the lubrication forces between neighbouring particles has been developed. The method is used to evaluate the effective Lamé moduli and the Poisson's ratio of the composite, for the particles in random configurations and in cubic lattices. A good agreement with experimental results given by Smith (1975) for particles in random configurations is observed, and also the numerical results on the effective moduli agree well with the results given by Nunan & Keller (1984) for particles in cubic lattices. 相似文献
16.
Incompressible elastic material with a periodic system of pores is considered. Processes are studied with a typical length
which is much more than the typical diameter of pores and the typical distance between pores. Porous material behaves as a
certain “effective” material without pores in such processes. The method of calculation of effective moduli based on mathematical
homogenization theory is described. The estimates for the effective moduli are proved. The results of numerical calculations
of effective moduli for materials with spherical and cubic pores are presented. The dependence of the effective moduli on
the volume fracture of pores is investigated. The explicit formulae for effective coefficients are deduced. Comparison with
the effective moduli for compressible materials is performed.
Presented at the Ninth International Conference on the Mechanics of Composite Materials, Riga, October, 1995.
Lomonosov Moscow State University, Department of Mathematics and Mechanics, Moscow. Published in Mekhanika Kompozitnykh Materialov,
No. 5, pp. 579–587, September–October, 1996. 相似文献
17.
F. Qi N. Phan-Tien X. J. Fan 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2000,26(4):92-113
This paper reports the numerical results of the effective moduli of a composite consisting of identical rigid spherical inclusions in a homogeneous isotropic elastic medium. The effective moduli are calculated for particles in simple, body-centered, face-centered cubic lattices, and in a random configuration. The numerical technique used is the Completed Double Layer Boundary Element Method (CDLBEM) augmented by a short-range lubrication approximation. The results agree well with previous numerical results obtained by a completely different technique. Agreement with experimental results for particles in random configurations is also observed. 相似文献
18.
Resonance methods for determining the complex shear moduli of orthotropic composites 总被引:1,自引:1,他引:0
V. S. Ekel’chik 《Mechanics of Composite Materials》2007,43(6):487-502
A survey of various methods for determining the complex elasticity and shear moduli from the resonant frequencies of flexural
and torsional vibrations of rectangular rods cut out from a plate of an orthotropic composite is presented. The errors in
the computed values of dynamic shear moduli caused by inaccuracies in the experimental determination of resonance frequencies
are examined. A new variant of the resonance method is developed, which permits one to find three complex shear moduli of
a composite from the resonant frequencies and the damping of torsional vibrations of three rods oriented along three symmetry
axes of the material. For computing the moduli in the case of an overdetermined system, an algorithm of nonlinear optimization
based on the least-squares method is recommended. From the results obtained it follows that, for determining the interlaminar
shear moduli with a necessary accuracy, the rods must be sufficiently thick. It is shown that a good agreement alone between
calculated and experimental frequencies of flexural and torsional vibrations of rods does not ensure a reliable determination
of the moduli of interlaminar shear if experiments are carried out on wide test specimens cut out from a thin plate. Recommendations
are given for the choice of geometrical sizes of test specimens for resonance experiments.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 6, pp. 721–744, November–December, 2007. 相似文献
19.
Results of an experimental investigation into the thermal behavior and mechanical properties of a room-temperature-cured epoxy
adhesive (diglycidyl ether of bisphenol A, DGEBA) cross-linked with polyetheramines and filled with different fillers, namely
nanosilica, liquid rubber (CTBN), and clay, are reported. The nanosilica and liquid rubber increased the flexural strength
and elastic modulus of the adhesive systems; the addition of clay particles raised the elastic modulus significantly, but
embrittled the adhesive. Establishing a correct cure time is very important for bonded-in timber structures, as it will affect
the bond strength. A study on the effect of cure time on the flexural strength was carried out, from which it follows that
the adhesives should be cured for at least 20 days at room temperature. The damping characteristics and the glass-transition
temperature of the adhesives were determined by using a dynamic mechanical thermal analysis. The results showed that the filled
adhesives had a higher storage modulus, which was in agreement with the elastic moduli determined from static bending tests.
The introduction of the fillers increased its glass-transition temperature considerably.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 5, pp. 599–614, September–October, 2006. 相似文献
20.
The operational properties (strength, heat conductivity, hygroscopic sorption, vapor permeability, and frost resistance) of
a heat-insulation composite of density 150–350 kg/m3 are investigated. The matrix consists of an aerated concrete substance and a disperse filler of expanded polystyrene crumbs
obtained by crushing the household polystyrene package waste. The macro-and microstructure of the composite are considered.
It is found that the operational properties of the material directly depend on its density, determined by the amount of the
cementing substance in the matrix.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 4, pp. 591–604, July–August, 2008. 相似文献