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1.
The theory of long-term damage of homogeneous materials is generalized to particulate composite materials. The damage of the
composite components is modeled by randomly dispersed micropores. The damage criterion for a microvolume is characterized
by its stress-rupture strength. It is determined by the dependence of the time to brittle failure on the difference between
the equivalent stress and its limit, which is the tensile strength, according to the Huber–Mises criterion, and assumed to
be a random function of coordinates. An equation of damage (porosity) balance in the composite components at an arbitrary
time is formulated. Algorithms of calculating the time dependence of microdamage and macrostresses or macrostrains are developed
and relevant curves are plotted in the case of unlimited microdurability
Translated from Prikladnaya Mekhanika, Vol. 44, No. 11, pp. 7–17, November 2008. 相似文献
2.
Deformation and long-term damage of orthotropic composites with limited stress-rupture microstrength
The theory of long-term microdamage of homogeneous materials based on the mechanics of stochastically inhomogeneous materials
is generalized to a composite with orthotropic inclusions. The damage of the composite components is modeled by randomly dispersed
micropores. The damage criterion for a microvolume is characterized by its stress-rupture strength. It is determined by the
dependence of the time to brittle failure on the difference between the equivalent stress and its limit, which is the tensile
strength, according to the Huber–Mises criterion, and assumed to be a random function of coordinates. Given macrostresses
or macrostrains, an equation of damage (porosity) balance in the composite components at an arbitrary time is derived. The
time dependence of microdamage and macrostresses or macrostrains in a discrete-fiber-reinforced composite with limited stress-rupture
microstrength described by a fractional-power function is plotted 相似文献
3.
The theory of long-term damage is generalized to particulate composite materials with physically nonlinear components. The
damage of the components is modeled by randomly dispersed micropores. The damage criterion for a microvolume is characterized
by its stress-rupture strength. It is determined by the dependence of the time to brittle failure on the difference between
the equivalent stress and its limit, which is the ultimate strength, according to the Huber–Mises criterion, and assumed to
be a random function of coordinates. An equation of damage (porosity) balance in the components at an arbitrary time is formulated.
Algorithms of calculating the time dependence of are developed. The effect on the nonlinearity of the matrix on the damage
and macrodeformation curves is examined 相似文献
4.
A theory of long-term damage of particulate composite materials under thermal load is proposed. The damage of the composite
components is modeled by randomly dispersed micropores. The failure criterion for a single microvolume is determined by its
stress-rupture strength, which, in turn, is determined by the dependence of the time to brittle failure on the difference
between the equivalent stress and its limit, which characterizes the ultimate strength according to the Schleicher–Nadai criterion.
The damage (porosity) balance equation is derived for an arbitrary time, taking the thermal effect into account. Algorithms
for calculating microdamage and macrostresses as functions of time are developed 相似文献
5.
The theory of long-term damage of homogeneous materials, which is based on the equations of the mechanics of stochastically
inhomogeneous materials, is generalized to composite materials reinforced with orthotropic ellipsoidal inclusions. The microdamage
of the composite components is modeled by randomly dispersed micropores. The failure criterion for a microvolume is characterized
by its stress-rupture strength. It is determined by the dependence of the time to brittle failure on the difference between
the equivalent stress and its limit, which is the tensile strength, according to the Huber–Mises criterion, and assumed to
be a random function of coordinates. Given macrostresses or macrostrains, an equation of porosity balance in the composite
components at an arbitrary time is formulated. The time dependence of microdamage and macrostresses or macrostrains is established
in the case of unlimited stress-rupture microstrength described by an exponential power function 相似文献
6.
The theory of long-term damage of homogeneous materials, which is based on the equations of the mechanics of stochastically
inhomogeneous materials, is generalized to discrete-fiber-reinforced composite materials. The microdamage of the composite
components is modeled by randomly dispersed micropores. The failure criterion for a microvolume is characterized by its stress-rupture
strength. It is determined by the dependence of the time to brittle failure on the difference between the equivalent stress
and its limit. Given macrostresses and macrostrains, an equation of damage (porosity) balance in the composite components
at an arbitrary time is formulated. The time dependence of microdamage and macrostresses or macrostrains is established in
the case of stress-rupture microstrength described by an exponential power function
Translated from Prikladnaya Mekhanika, Vol. 45, No. 2, pp. 19–29, February 2009. 相似文献
7.
The theory of long-term damage of homogeneous materials is generalized to layered materials. The damage of the components
(layers) is modeled by randomly dispersed micropores. The damage criterion for a microvolume is characterized by its stress-rupture
strength. It is determined by the dependence of the time to brittle failure on the difference between the equivalent stress
and its limit, which is the tensile strength, according to the Huber–Mises criterion, and assumed to be a random function
of coordinates. An equation of damage (porosity) balance in the components at an arbitrary time is formulated. Algorithms
of calculating the time dependence of microdamage and macrostresses or macrostrains are developed and corresponding curves
are plotted in the case of a fractional power microdurability function 相似文献
8.
The theory of long-term damage of homogeneous materials is generalized to layered materials. The damage of the components
is modeled by randomly dispersed micropores. The damage criterion for a microvolume is characterized by its stress-rupture
strength. It is determined by the exponential power dependence of the time to brittle failure on the difference between the
equivalent stress and its limit, which is the tensile strength, according to the Huber–Mises criterion, and assumed to be
a random function of coordinates. An equation of damage (porosity) balance in the components at an arbitrary time is formulated.
Algorithms of calculating the time dependence of microdamage and macrostresses or macrostrains are developed and corresponding
curves are plotted in the case of exponential power microdurability function 相似文献
9.
A theory of long-term damage of physically nonlinear homogeneous materials is proposed. Damage is modeled by randomly dispersed
micropores. The failure criterion for a microvolume is characterized by its stress-rupture strength. It is determined by the
dependence of the time to brittle fracture on the difference between the equivalent stress and its limit, which is the ultimate
strength, according to the Huber–Mises criterion, and assumed to be a random function of coordinates. An equation of damage
(porosity) balance in a physically nonlinear material at an arbitrary time is formulated. Algorithms of calculating the time
dependence of microdamage and macrostresses are developed and the corresponding curves are plotted. The effect of the nonlinearity
of the material on its macrodeformation and damage is analyzed 相似文献
10.
A theory of long-term damage of homogeneous materials under thermal load is proposed. The damage of the material is modeled
by randomly dispersed micropores. The failure criterion for a single microvolume is determined by its stress-rupture strength,
which, in turn, is determined by the dependence of the time to brittle failure on the difference between the equivalent stress
and its limit, which characterizes the ultimate strength according to the Schleicher–Nadai criterion. The damage (porosity)
balance equation is derived for an arbitrary time, taking the thermal effect into account. Algorithms for calculating microdamage
and macrostresses as functions of time are developed, and respective curves are plotted. The effect of temperature on the
macrodeformation and damage curves is studied 相似文献
11.
The studies of mathematical models for the coupled processes of deformation and long-time damage of stochastic composite materials
are systematized. Damage is modeled by stochastically arranged micropores. The damage of a single microvolume is characterized
by its stress-rupture strength determined by the dependence of the time to brittle fracture on the difference between the
equivalent stress and its limit, which is the ultimate strength, according to the Huber–Mises or Schleicher–Nadai criteria,
and assumed to be a random function of coordinates. The equation of damage balance at an arbitrary time and the equations
relating macrostresses and macrostrains constitute a closed system. Algorithms of calculating the time dependence of microdamage
and macrostresses are developed. The effect of temperature and nonlinearity on the curves is studied 相似文献
12.
The theory of long-term damage is generalized to unidirectional fibrous composites. The damage of the matrix is modeled by
randomly dispersed micropores. The damage criterion for a microvolume is characterized by its stress-rupture strength. It
is determined by the dependence of the time to brittle failure on the difference between the equivalent stress and its limit,
which is the ultimate strength, according to the Huber–Mises criterion, and assumed to be a random function of coordinates.
An equation of damage (porosity) balance in the matrix at an arbitrary time is formulated. Algorithms of calculating the time
dependence of microdamage and macrostresses or macrostrains are developed and corresponding curves are plotted in the case
of stress-rupture microstrength described by a fractional power function 相似文献
13.
The theory of long-term damage is generalized to fibrous composites. The damage of the matrix is modeled by randomly dispersed
micropores. The damage criterion for a microvolume is characterized by its stress-rupture strength. It is determined by the
dependence of the time to brittle failure on the difference between the equivalent stress and its limit, which is the ultimate
strength, according to the Huber–von Mises criterion, and assumed to be a random function of coordinates. An equation of damage
(porosity) balance in the matrix at an arbitrary time is formulated. Algorithms of calculating the time dependence of microdamage
and macrostresses or macrostrains are developed and corresponding curves are plotted in the case of stress-rupture microstrength
described by an exponential power function 相似文献
14.
A theory of long-term damage of fibrous composites under thermal loading is set up. The damage of the matrix is modeled by
randomly dispersed micropores. The failure criterion for a microvolume is characterized by its stress-rupture strength. It
is determined by the dependence of the time to brittle fracture on the difference between the equivalent stress and its limit,
which is the ultimate strength, according to the Schleicher–Nadai failure criterion, and assumed to be a random function of
coordinates. An equation of damage (porosity) balance in the matrix at an arbitrary time is formulated taking into account
the thermal component. Algorithms of calculating the time dependence of microdamage and macrostresses are developed. Corresponding
curves are plotted. The effect of temperature on the deformation and microdamage of the material is studied 相似文献
15.
The failure criterion for a microvolume is characterized by its stress-rupture strength. It is determined by the dependence
of the time to brittle fracture on the difference between the equivalent stress and its limit, which is the ultimate strength,
according to the Schleicher–Nadai failure criterion, and assumed to be a random function of coordinates. An equation of damage
(porosity) balance in the layers at an arbitrary time is formulated taking into account the thermal component. Algorithms
of calculating the time dependence of microdamage and macrostresses are developed. Corresponding curves are plotted. The effect
of temperature on the deformation and microdamage of the layers is studied 相似文献
16.
The damage process is modeled by randomly dispersed micropores occurring in places of destroyed microvolumes according to
the stress-rupture microstrength, which is determined by the dependence of the time to brittle failure on the difference between
the equivalent stress and its limit, according to the Huber–Mises criterion, and is a random function of coordinates. Given
microstresses or microstrains, the equations of porosity balance at an arbitrary time are derived. Together with the macrostress–macrostrain
relationships for a discrete fibrous composite with porous components, they describe the coupled processes of deformation
and long-term damage. A specific problem with a bounded stress-rupture microstrength function is solved
Translated from Prikladnaya Mekhanika, Vol. 45, No. 1, pp. 71–81, January 2009. 相似文献
17.
Accelerated aging of unidirectional hybrid composites under the long-term elevated temperature and moisture concentration 总被引:2,自引:0,他引:2
N. BoualemZ. Sereir 《Theoretical and Applied Fracture Mechanics》2011,55(1):68-75
Despite their high performances, composites with polymer matrix are very sensible to the increase in temperature and moisture concentration. During long years of services, both phenomena cause a critical transient hygrothermal transverse stresses, particularly at first-ply; i.e. at two edges of the composite plates. Therefore, significant degradation of hygrothermal characteristics and ultimate strengths of materials are occurred. To get an explicit relation between the durability and the damage probability of the composite, quadratic failure criterion in stress space is used. This criterion enables us to find a direct relation between transient hygrothermal stresses produced by the increase in temperature and moisture concentration and the ultimate strengths. It is necessary to calculate the strength ratio R from initial to saturation time for each condition imposed of temperature and moisture concentration. The strength ratio gives a point of view on the damage probability of the composite plates, where the rupture occurs if R = 1. In order to limit the consequences of simultaneous effects of temperature and moisture concentration, unidirectional hybrid composites in graphite epoxy was proposed. To reach this aim, hygrothermal transverse stresses are calculated through the thickness of unidirectional hybrid plate. Finally, the strength ratio was evaluated along of the plate with a gradual increase in temperature and moisture concentration. 相似文献
18.
L. P. Khoroshun 《International Applied Mechanics》2007,43(2):217-227
The principles of the theory of long-term damage based on the mechanics of stochastically inhomogeneous media are set out.
The process of damage is modeled as randomly dispersed micropores resulting from the destruction of microvolumes. A failure
criterion for a single microvolume is associated with its long-term strength dependent on the relationship of the time to
brittle failure and the difference between the equivalent stress and the Huber-von Mises failure stress, which is assumed
to be a random function of coordinates. The stochastic elasticity equations for porous media are used to determine the effective
moduli and the stress-strain state of microdamaged materials. The porosity balance equation is derived in finite-time and
differential-time forms for given macrostresses or macrostrains and arbitrary time using the properties of the distribution
function and the ergodicity of the random field of short-term strength as well as the dependence of the time to brittle failure
on the stress state and the short-term strength. The macrostress-macrostrain relationship and the porosity balance equation
describe the coupled processes of deformation and long-term damage
__________
Translated from Prikladnaya Mekhanika, Vol. 43, No. 2, pp. 108–121, February 2007.
For the centenary of the birth of G. N. Savin. 相似文献
19.
The structural theory of short-term damage is generalized to the case where the undamaged components of a granular composite deform nonlinearly. The basis for this generalization is the stochastic elasticity equations for a granular composite with porous components whose skeletons deform nonlinearly. Microvolumes of the composite components meet the Huber–Mises failure criterion. Damaged microvolume balance equations are derived for the physically nonlinear materials of the components. Together with the equations relating macrostresses and macrostrains of a granular composite with porous nonlinear components, they constitute a closed-form system. The system describes the coupled processes of physically nonlinear deformation and microdamage. Algorithms for calculating the microdamage–macrostrain relationship and plotting deformation diagrams are proposed. Uniaxial tension curves are plotted for the case where microdamages occur in the linearly hardened matrix and do not in the inclusions, which are linearly elastic 相似文献
20.
The structural theory of short-term damage is generalized to the case where the undamaged components of an N-component laminar composite deform nonlinearly. The basis for this generalization is the stochastic elasticity equations for an N-component laminar composite with porous components whose skeleton deforms nonlinearly. Microvolumes of the composite components meet the Huber–Mises failure criterion. Damaged microvolume balance equations are derived for the physically nonlinear materials of the composite components. Together with the equations relating macrostresses and macrostrains of the laminar composite with porous nonlinear components, they constitute a closed-form system. This system describes the coupled processes of physically nonlinear deformation and microdamage. For a two-component laminar composite, algorithms for calculating the microdamage–macrostrain relationship and plotting deformation curves are proposed. Uniaxial tension curves are plotted for the case where microdamages occur in the linearly hardening component and do not in the linearly elastic component 相似文献