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1.
A series of triaxial compression experiments were preformed for the coarse marble samples under different loading paths by
the rock mechanics servo-controlled testing system. Based on the experimental results of complete stress-strain curves, the
influence of loading path on the strength and deformation failure behavior of coarse marble is made a detailed analysis. Three
loading paths (Paths I–III) are put forward to confirm the strength parameters (cohesion and internal friction angle) of coarse
marble in accordance with linear Mohr-Coulomb criterion. Compared among the strength parameters, two loading paths (i.e. Path
II by stepping up the confining pressure and Path III by reducing the confining pressure after peak strength) are suggested
to confirm the triaxial strengths of rock under different confining pressures by only one sample, which is very applicable
for a kind of rock that has obvious plastic and ductile deformation behavior (e.g. marble, chalk, mudstone, etc.). In order
to investigate re-fracture mechanical behavior of rock material, three loading paths (Paths IV–VI) are also put forward for
flawed coarse marble. The peak strength and deformation failure mode of flawed coarse marble are found depending on the loading
paths (Paths IV–VI). Under lower confining pressures, the peak strength and Young’s modulus of damage sample (compressed until
post-peak stress under higher confining pressure) are all lower compared with that of flawed sample; moreover mechanical parameter
of damage sample is lower for the larger compressed post-peak plastic deformation of coarse marble. However under higher confining
pressures (e.g. σ
3 = 30 MPa), the axial supporting capacity and elastic modulus of damage coarse marble (compressed until post-peak stress under
lower confining pressure) is not related to the loading path, while the deformation modulus and peak strain of damage sample
depend on the difference of initial confining pressure and post-peak plastic deformation. The friction among crystal grains
determines the strength behavior of flawed coarse marble under various loading paths. In the end, the effect of loading path
on failure mode of intact and flawed coarse marble is also investigated. The present research provides increased understanding
of the fundamental nature of rock failure under different loading paths. 相似文献
2.
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
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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
3.
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
4.
A. M. Kovrizhnykh V. D. Baryshnikov A. V. Manakov A. F. Nikitenko 《Journal of Applied Mechanics and Technical Physics》2007,48(6):871-877
It is proposed to construct long-term strength and creep relations for metals on the basis of the Coulomb-Mohr criterion.
The creep equations and the long-term strength criterion for plane stress are analyzed in detail. Results of long-term strength
calculations are compared with data of experiments with metallic materials. It is established that theoretical and experimental
results are in satisfactory agreement.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 6, pp. 115–123, November–December, 2007. 相似文献
5.
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
6.
E. V. Karpov 《Journal of Applied Mechanics and Technical Physics》2009,50(1):163-169
This paper gives the results of an experimental study of the deformation and fracture of a spheroplast under uniaxial low-cycle
loading (compression and unloading) at a temperature T = 25 and 100°C. Various mechanisms of damage accumulation at various temperatures and degrees of damage to the material are studied. The
experimental results are compared with the well-known dependences taking into account damage accumulation for metals. It is
established that the basic propositions of these theories are suitable for the low-cycle fracture of spheroplast — a ductile
material of complex structure.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 1, pp. 197–204, January–February, 2009. 相似文献
7.
V. Rizov 《Archive of Applied Mechanics (Ingenieur Archiv)》2009,79(3):205-212
Usually when analyzing the mechanical response of foam-cored fiber-reinforced composite sandwich structures to localized static
loading, the face sheets are treated as a linear-elastic material and no damage initiation and growth is considered. However,
practice shows that at higher indentation magnitudes damage develops in the face sheet in the area of contact with the indentor,
which could lead to local failure of the face laminate due to the loss of bending stiffness and strength. Therefore, the main
objective of the present study is to develop a damage model for predicting the local failure in the composite face sheet and
its influence on the load–displacement behavior of sandwich structures under local loading. For this purpose, the Hoffman
failure criterion is incorporated into a finite element modeling procedure using the ABAQUS program system. Results deducted
from the modeling procedure are compared with experimental data obtained in the case of static indentation tests performed
on sandwich beam specimens using steel cylindrical indentors. It is shown that taking into account the damage in the face
sheet leads to a substantial improvement in the performance of the model when simulating the mechanical behavior of the sandwich
structures at higher indentation values. 相似文献
8.
N. N. Belov N. T. Yugov D. G. Kopanitsa O. V. Kabantsev A. A. Yugov A. N. Ovechkina 《Journal of Applied Mechanics and Technical Physics》2008,49(1):148-155
This paper reports the results of experiments with reinforced concrete column models subjected to repeated longitudinal impact
loading using a pile driver. The strength of the column models is analyzed by comparing experimental data with results of
mathematical modeling.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 1, pp. 181–190, January–February, 2008. 相似文献
9.
S. V. Suknev 《Journal of Applied Mechanics and Technical Physics》2000,41(3):526-530
The strength of a plate with an elliptic hole under uniaxial tension or compression is estimated for arbitrary angles between
the ellipse axes and the direction of loading with the use of the gradient strength criterion. The calculated critical stress
agrees with the existing experimental data.
Institute of Physicotechnical Problems of the North, Siberian, Division, Russian Academy of Sciences, Yakutsk 677891. Translated
from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 3, pp. 163–168, May–June, 2000. 相似文献
10.
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
11.
A reliable prediction of ductile failure in metals is still a wide-open matter of research. Several models are available in
the literature, ranging from empirical criteria, porosity-based models and continuum damage mechanics (CDM). One major issue
is the accurate identification of parameters which describe material behavior. For some damage models, parameter identification
is more or less straightforward, being possible to perform experiments for their evaluation. For the others, direct calibration
from laboratory tests is not possible, so that the approach of inverse methods is required for a proper identification. In
material model calibration, the inverse approach consists in a non-linear iterative fitting of a parameter-dependent load–displacement
curve (coming from a FEM simulation) on the experimental specimen response. The test is usually a tensile test on a round-notched
cylindrical bar. The present paper shows a novel inverse procedure aimed to estimate the material parameters of the Gurson–Tvergaard–Needleman
(GTN) porosity-based plastic damage model by means of experimental data collected using image analysis. The use of digital
image processing allows to substitute the load–displacement curve with other global quantities resulting from the measuring
of specimen profile during loading. The advantage of this analysis is that more data are available for calibration thus allowing
a greater level of confidence and accuracy in model parameter evaluation. 相似文献
12.
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
13.
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
14.
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
15.
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
16.
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
17.
N. A. Veklich A. M. Lokoshchenko P. N. Veklich 《Journal of Applied Mechanics and Technical Physics》2007,48(5):774-778
The high-temperature extension of metals to fracture is modeled for creep at constant stress or at constant strain rate. The
dependence of the ultimate fracture strain on the loading factor (stress or strain rate) is studied. The nonmonotonic nature
of this dependence with an internal maximum is described using the Rabotnov kinetic theory with one and two damage parameters.
Available experimental data are analyzed.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 183–188, September–October, 2007. 相似文献
18.
The studies on the deformation and short-term damage of physically nonlinear homogeneous and composite materials are systemized.
A single microdamage is modeled by an empty quasispherical pore in place of a microvolume damaged in accordance with the Huber–von
Mises failure criterion. The ultimate microstrength is assumed to be a random function of coordinates. The porosity balance
equation is derived. Together with the macrostress–macrostrain relationship, it constitutes a closed-form system of equations.
The damage–macrostrain relationship and macrostress–macrostrain curves for homogeneous and composite materials are analyzed 相似文献
19.
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
20.
A technique for interpreting rock specimen compression testing data is proposed. It consists of mathematical modeling of the
loading of a specimen containing the sliding line L, on which the stresses are continuous and the displacements are discontinuous.
At each step of loading the values of a jump of displacements on L are found from the experimentally known stress-strain dependences.
The empirical relations describing the strain process on the sliding line are found using these results. Based on Stavrogin's
experimental data, we estimate the parameters of the dependence of the peak strength of the interblock contact on the shift
from the normal stress.
Mining Institute, Siberian Division, Russian Academy of Sciences, Novosibirsk 630091. Translated from Prikladnaya Mekhanika
i Tekhnicheskaya Fizika, Vol. 39, No. 6, pp. 142–147, November–December, 1998. 相似文献