共查询到20条相似文献,搜索用时 171 毫秒
1.
L. A. Golotina L. L. Kozhevnikova T. B. Koshkina 《Mechanics of Composite Materials》2007,43(2):127-132
A structural model is suggested for elastomers filled with particles of two fractions — with diameters exceeding 10 μm and submicronic ones. In each fraction, the particle diameter varies randomly, but between the fractions, the average particle
diameter differs by several orders of magnitude. It is assumed that the small particles, together with the matrix, behave
as a homogeneous medium relative to the large ones. By using this model, the mechanical behavior of composites based on elastomers
filled with different volume contents of solid particles is investigated.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 2, pp. 191–200, March–April, 2007. 相似文献
2.
N. A. Shul'ga 《Journal of Mathematical Sciences》1997,86(6):3149-3152
We develop a model of elastic strain of a composite material with interphase imperfections. In the context of this model we
construct a continuous model of first order (theory of effective models) for stratified and unidirectional fibrous compounds.
We determine the velocities of propagation of long (compared with the size of the structure) waves in any direction. We exhibit
the possible characteristic regularities of the influence of interphase imperfections on the value of the velocities. Bibliography:
6 titles.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 26, 1996, pp. 100–105. 相似文献
3.
Two polyester-based polymer concretes with various volume content of diabase as an extender and aggregate are tested in creep
under compression at different stress levels. The phenomenological and structural approaches are both used to analyze the
experimental data. Common features of changes in the instantaneous and creep compliances are clarified, and a phenomenological
creep model which accounts for the changes in the instantaneous compliance and in the retardation spectrum depending on the
stress level is developed. It is shown that the model can be used to describe the experimental results of stress relaxation
and creep under repeated loading. Modeling of the composite structure and subsequent solution of the optimization problem
confirm the possibility of the existence of an interphase layer more compliant than the binder. A direct correlation between
the interphase volume content and the instantaneous compliance of the composite is revealed. It is found that the distinction
in nonlinearity of the viscoelastic behavior of the two polymer concretes under investigation can be due to the difference
in their porosity.
Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000.)
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 147–164, 2000. 相似文献
4.
Yu. N. Kononov 《Journal of Mathematical Sciences》1997,86(6):3157-3160
We study the stability of uniform rectilinear motion of a system of solid bodies connected by springs and partly filled with
an ideal fluid. The frequency equation obtained is studied as a function of the fundamental parameters of the mechanical system.
Bibliography: 5 titles.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 26, 1996, pp. 111–116. 相似文献
5.
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
6.
An epoxy resin (Epon 828) was filled with single- and multiwalled carbon nanotubes (SWCNT and MWCNT) in two steps by using
the high shear mixing and ultrasonication techniques. The melt flow of the composites was characterized in a plate/plate rheometer.
The thermomechanical properties of the composites were determined in dynamic mechanical analysis tests performed at various
frequencies and temperatures. It was found that the incorporation of SWCNT or MWCNT increased the viscosity and stiffness
of epoxy above its glass-transition temperature. The time-temperature superposition principle was employed to estimate the
storage modulus of the composites as a function of frequency (f = 10–33–103 Hz) in the form of master curves. 相似文献
7.
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
8.
9.
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
10.
L. A. Fil'shtinskii 《Journal of Mathematical Sciences》1998,92(5):4161-4163
We construct fundamental solutions of the two-dimensional equations of electroelasticity for antiplanar strain of a piezoceramic
space with an interphase defect. We study the orders of the powers of the singularities at the vertices of the defect for
two cases: an interphase crack and a stiff fiber continuously joined to the upper half-space which has flaked off the lower
half-space. The solution is constructed in closed form.
Bibliography: 4 titles.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 28, 1998, pp. 62–67. 相似文献
11.
Aurel Bejancu 《Journal of Nonlinear Science》2012,22(2):213-233
In the first part of the paper we present a new point of view on the geometry of nonholonomic mechanical systems with linear
and affine constraints. The main geometric object of the paper is the nonholonomic connection on the distribution of constraints.
By using this connection and adapted frame fields, we obtain the Newton forms of Lagrange–d’Alembert equations for nonholonomic
mechanical systems with linear and affine constraints. In the second part of the paper, we show that the Kaluza–Klein theory
is best presented and explained by using the framework of nonholonomic mechanical systems. We show that the geodesics of the
Kaluza–Klein space, which are tangent to the electromagnetic distribution, coincide with the solutions of Lagrange–d’Alembert
equations for a nonholonomic mechanical system with linear constraints, and their projections on the spacetime are the geodesics
from general relativity. Any other geodesic of the Kaluza–Klein space that is not tangent to the electromagnetic distribution
is also a solution of Lagrange–d’Alembert equations, but for affine constraints. In particular, some of these geodesics project
exactly on the solutions of the Lorentz force equations of the spacetime. 相似文献
12.
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
13.
L. A. Molotkov 《Journal of Mathematical Sciences》1995,73(3):389-396
The two-phase effective model of a cracked medium with cracks filled with liquid is extended to the case where cracks have
finite length. On the basis of the equations obtained for the generalized effective model, the expressions of kinetic and
potential energies and energy streams along axes are derived. This also shows that attenuation is absent. bibliography: 6
titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 186, pp. 142–153, 1990.
Translated by L. A. Molotkov. 相似文献
14.
L. A. Molotkov 《Journal of Mathematical Sciences》1996,79(4):1247-1259
An effective two-phase model of media with cracks filled with liquid is generalized to the case of finite cracks. Wave propagation
in a half-space and in a free layer, described by the new model, is investigated. The results are compared with experimental
data and with corresponding results in the case of media with infinite cracks. Bibliography: 11 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 203, 1992, pp. 137–155.
Translated by L. A. Molotkov. 相似文献
15.
16.
In this work, a model is developed which allows one to determine the thickness and properties of the interphase layer in unidirectional and filled composites, assuming that the materials of the interphase, matrix, and fillers may have a fractal structure, and to predict the properties of composites with interphases. Using a set of computer programs elaborated, the corresponding calculations are carried out for glass-epoxy composites, epoxy carboplastics, and graphite-filled epoxy polymers. 相似文献
17.
Yu. A. Gorbatkina V. G. Ivanova-Mumjieva A. S. Putyatina T. M. Ul’yanova 《Mechanics of Composite Materials》2007,43(1):1-8
The concentration dependences of adhesive strength are investigated for fiber/dispersedly filled epoxy matrix systems. The
measurements were carried out using an improved model of adhesiometer under normal conditions at a constant rate of loading.
It is shown that the adhesive strength as a function of filler concentration has a maximum, which is more or less pronounced.
The location of the maximum depends on the nature of filler and particle geometry. The increase in the adhesive strength at
the maximum reaches 20–30% in comparison with that for the unfilled epoxy matrix. Since the interfacial strength between steel
wire and all the mineral powders investigated is zero, the growth in the adhesive strength upon introduction of a finely divided
filler in polymer binders is rather un expected. The possible reasons for the phenomenon observed are discussed.
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Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 1, pp. 3–14, January–February, 2007. 相似文献
18.
The results of an experimental and theoretical investigation into the deformation behavior of CFRP-confined square and rectangular
concrete columns under axial loads are presented. Three types of columns are considered: unwrapped; fully wrapped; and fully
wrapped, with L-slaped steel angles placed at the corners. A mechanical deformation model for them is proposed, which is based
on a nonuniform distribution of the stresses caused by the confining device. The results given by the model are in a good
agreement with the experimental results obtained.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 3, pp. 417–442, May–June, 2008. 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.
In this presentation, a review is given on the main effects of mineral particulate fillers (with an aspect ratio of about
unity) on the deformation and fracture of amorphous and semicrystalline thermoplastic and thermosetting polymers. Elastomeric
modifiers, polymer blends, and filled elastomers are not considered here. Fillers are generally used to reduce cost as well
as the thermal sensitivity of mechanical properties of the matrix material and to improve, if possible, the strength and toughness.
The addition of particulate fillers influences all stages of the fabrication and use of the resulting composites. We focus
on the effects of a stiff second phase on elastic moduli, matrix structure, and on deformation, creep, and failure mechanisms.
As the main mechanisms, particle-matrix debonding, void formation, and matrix microshear yielding are identified. Toughness
is less sensitive to the quality of adhesion since particle-matrix debonding and formation of voids can be tolerated. If well
controlled, debonding contributes to deformation (formation of voids should be well distributed in space and time). Reference
is also made to the surprising and positive effect of CaCO3 particles on the toughness and impact resistance of HDPE, which increases at small interparticle distances due to interfacial
effects on lamellar growth in the ligament area.
Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000).
Published in Mekhanika Kompozitnykh Materialov, Vol. 36, No. 3, pp. 305–316, March–April, 2000. 相似文献