共查询到20条相似文献,搜索用时 31 毫秒
1.
M. P. Malezhik O. P. Malezhik A. I. Zirka I. S. Chernyshenko 《International Applied Mechanics》2005,41(12):1399-1406
The method of dynamic photoelasticity is used to study the dynamic failure of structural members in the form of plates with
a curvilinear (circular or elliptic) hole and an isolated crack under impulsive loading. The time-dependences of the stress
intensity factors and the crack tip velocity are investigated for two types of models
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Translated from Prikladnaya Mekhanika, Vol. 41, No. 12, pp. 84–92, December 2005. 相似文献
2.
G. V. Gavrilov 《International Applied Mechanics》2010,46(4):422-428
The paper addresses subcritical growth of a crack in a thin isotropic plate made of an aging viscoelastic material with time-dependent
elastic modulus. The behavior of the material is described by Arutyunyan’s creep theory. To simulate fracture, a modified
Leonov–Panasyuk–Dugdale model and a critical crack opening displacement criterion are used. An equation describing the subcritical
growth of the crack is derived assuming that Poisson’s ratio is constant. As an example, the critical loads are determined,
and curves of subcritical crack growth are plotted for a specific material. The results are compared with the case of constant
elastic modulus 相似文献
3.
E. V. Vtorushin 《Journal of Applied Mechanics and Technical Physics》2007,48(5):737-742
A homogeneous two-dimensional body with a crack of variable length is considered. At the crack edges, conditions are formulated
in the form of inequalities that describe mutual nonpenetration of the edges. The derivative of the elastic-energy functional
with respect to the length of the curvilinear crack is analyzed. It is shown that the derivative is independent of the crack
path, provided that the curve along which the crack propagates is reasonably smooth.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 138–145, September–October, 2007. 相似文献
4.
A. P. Shabanov 《Journal of Applied Mechanics and Technical Physics》2009,50(4):684-690
A model for crack growth is proposed based on studies of the variation in the curvature radius at the crack tip during cyclic
loading. Relations are obtained between mechanical material characteristics, crack geometry, and the rate of crack growth
in a structure under cyclic loading.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 167–175, July–August, 2009. 相似文献
5.
M. V. Mir-Salim-zade 《Journal of Applied Mechanics and Technical Physics》2007,48(4):562-570
The fracture mechanics problem of crack initiation in a stiffened plate is considered. The crack nucleus is modeled by a prefracture
zone with bonds between the crack faces, which is treated as a region of weakened interparticle bonds of the material. The
boundary-value problem of the equilibrium of a stiffened plate with a crack nucleus reduces to a nonlinear singular integrodifferential
equation with a Cauchy type kernel. The strains in the crack initiation zone are found by solving this equation. The case
of the stress state of the plate with a periodic system of prefracture zones is considered.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 4, pp. 111–120, July–August, 2007. 相似文献
6.
V. A. Kovtunenko I. V. Sukhorukov 《Journal of Applied Mechanics and Technical Physics》2006,47(5):704-713
For the evolutionary problem describing crack propagation in a solid with allowance for the irreversible work of plastic deformation
due to the crack propagation, a general optimization formulation is proposed and investigated. For the optimum crack, data
on the H2-smoothnesses of the displacement field in the solid and, hence, on the finiteness of the stress at the crack tip, are obtained.
The solvability of the optimization problem (i.e., the existence of an optimum crack) is proved for a curvilinear crack propagation
path specified a priori. For the particular case of a straight path, a generalized criterion of crack growth is proposed.
The question of the choice of a crack propagation path is discussed and a comparison with existing fracture criteria is made.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 5, pp. 107–118, September–October, 2006. 相似文献
7.
The mechanical model was established for the anti-plane fracture problem of a functionally graded coating–substrate system
with a coating crack inclined to the weak/micro-discontinuous interface. The Cauchy singular integral equation for the crack
was derived using Fourier integral transform, and the Lobatto–Chebyshev collocation method put up by Erdogan and Gupta was
used to get its numerical solution. Finally, the effects of the weak/micro-discontinuity of the interface on SIFs were analyzed,
the “affected regions” corresponding to the two crack tips have been obtained and their engineering significance was discussed.
It was indicated that, for the crack tip in the corresponding “affected region”, to reduce the weak-discontinuity of the interface
and to make the interface micro-discontinuous are the two effective ways to reduce the SIF, and the latter way always has
more remarkable SIF-reduction effect. For the crack tip outside the “affected region”, its SIF is mainly influenced by material
stiffness, and to prevent such a tip from growing toward the interface “softer coating and stiffer substrate” is a more advantageous
combination than “stiffer coating and softer substrate”. 相似文献
8.
V. A. Saraikin 《Journal of Applied Mechanics and Technical Physics》1999,40(5):903-907
Equations are derived for stress concentration near a crack of closed contour lying in a plane. A system of one-dimensional
integral equations for the concentration factor is obtained. The right sides of the equations contain the initial approximation—a
solution of the problem of a circular crack whose sides are acted upon by nonaxisymmetric loading.
Mining Institute, Siberian Division, Russian Academy of Sciences, Novosibirsk 630091. Translated from Prikladnaya Mekhanika
i Tekhnicheskaya Fizika, Vol. 40, No. 5, pp. 143–148, September–October, 1999. 相似文献
9.
O. P. Alekseenko A. M. Vaisman A. F. Zazovskii 《Journal of Applied Mechanics and Technical Physics》1998,39(3):454-461
An algorithm that permits one to find a solution of the Perkins-Kern-Nordgren problem for standard regimes of hydraulic fracturing
is suggested. The universal qualitative specifics, of the behavior of a crack is shown; in particular, the asymptotics of
crack opening at the tip is found, and it is shown that the character of the crack is determined by the rate of increase or
decrease in the crack size.
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 149–157, May–June, 1998. 相似文献
10.
A crack is represented as a continuous set of linear dislocations. Simple analytical expressions are obtained for the potential
and kinetic energies of the environment of moving cracks and the attached mass of cracks for an arbitrary form of the stress
applied to the crack P(x). It is shown that the indicated analytical expressions are bilinear integrals of the functions P(x)
and ∂P(x)/∂x. These integrals are calculated in explicit form for a constant stress over the entire crack length and the stress
due to the action of molecular adhesion forces in a narrow region near the crack openings. It is shown that the calculation
results does not depend on the form of molecular adhesion forces. The proposed approach to describing cracks and calculations
based on it has made it possible for the first time to obtain a complete analytical expression for the limiting crack propagation
velocity in elastic materials as a function of the main mechanical characteristics of such materials.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 158–166, July–August, 2009. 相似文献
11.
V. V. Mykhas’kiv N. D. Grilitskii I. O. Butrak 《Journal of Applied Mechanics and Technical Physics》2006,47(4):556-563
A three-dimensional wave field formed owing to diffraction of low-frequency waves on a curved crack in an infinite elastic
solid at a large distance from the defect is studied by the method of boundary integral equations. Direction diagrams of the
scattered field versus the excentricity of the crack surface and wavenumber are obtained for different directions of incidence
of planar longitudinal waves onto a gently sloping spheroidal crack.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 115–123, July–August, 2006. 相似文献
12.
V. M. Tikhomirov 《Journal of Applied Mechanics and Technical Physics》2008,49(5):864-871
Crack propagation under alternating loading is investigated. Relations between the growth rate of a fatigue defect and loading
parameters and the expression for the stress intensity factor are derived for compression of a cracked solid taking into account
the possible contact of the crack faces. A model for the deformation of a small region near the crack tip is proposed which
allows one to formulate the conditions of residual opening of a growing fatigue crack. The experimental data obtained in tests
of steel samples are compared with the results of calculation using the developed procedure.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 5, pp. 190–198, September–October, 2008. 相似文献
13.
Vladimir Kobelev 《Meccanica》2006,41(6):653-660
Failure of a composite is a complex process accompanied by irreversible changes in the microstructure of the material. Microscopic
mechanisms are known of the accumulation of damage and failure of the type of localized and multiple ruptures of the fibers
delamination along interphase boundaries, and also mechanisms associated with fracture of fibers. In this work, we propose
a mathematical model of the local mechanism of failure of a composite material randomly reinforced with a system of short
fibers. We implement the Cosserat moment model of crack tip for filament material, reinforced with whiskers or in fiber- reinforced
polycrystalline materials. It is assumed that the angular distribution of the fibers is isotropic and the elastic characteristics
of the fibers are considerably higher than the elastic constants of the matrix. We implement the homogenization procedure
for the effective Cosserat constants similarly to the effective elastic constants. The singular solution in the vicinity of
the crack tip in the Cosserat moment model is found. Using this solution, we examine the bending stresses in the filaments
due to effective moment stresses in the material. The constructed model describes the phenomenon of fracture of the fibers
occurring during crack propagation in those composites. The following assumptions are used as the main hypotheses for the
micromechanical model. The matrix contains a nucleation crack. When the load is increased the crack grows and its boundary
comes into contact with the reinforcing fibers. A further increase of the stress causes bending of the fiber. When~the fiber
curvature reaches a specific critical value, the fiber ruptures. If the stress at infinity is given, the fibers no longer
delay the development of failure during crack propagation The degree of bending distortion of the fiber in the vicinity of
the boundary of the crack is determined by the moment model of the material. The necessity to take into account the moment
stresses in the failure theory of the reinforced material was stressed in [Muki and Sternberg (1965) Zeitschrift f angew Math
und Phys 16:611–615; Garajeu and Soos (2003) Math Mech Solids 8(2):189–218; Ostoja-Starzewski et al (1999) Mech Res Commun
26:387–396]. The moment Cosserat stresses were accounted also for inhomogeneous biomechanical materials by Buechner and Lakes
(2003) Bio Mech Model Mechanobiol 1: 295–301. We should also mention the important methodological studies [Sternberg and Muki
(1967) J Solids Struct 1:69–95; Atkinson and Leppington (1977) Int J Solids Struct 13: 1103–1122] concerned with the moment
stresses in homogeneous fracture mechanics. 相似文献
14.
Piero Villaggio 《Continuum Mechanics and Thermodynamics》1998,10(4):233-240
The root of a tree develops the twofold function of absorbing water mixed with mineral salts, and anchoring the plant to
the substrate. The former activity is the more important in determining the spreading of a root. If, however, the root is
regarded only as a bundle of stiffeners implanted in a semi–infinite elastic medium and we want to optimize its shape, then
the problem can be reduced to an optimization problem in elasticity.
Received June 24, 1997 相似文献
15.
This paper is concerned with dynamic problems in fracture mechanics for elastic solids having cracks with contacting faces.
The contact problem for a penny-shaped crack with a nonzero initial opening under normally incident harmonic wave is solved
by the method of boundary integral equations. The solutions are compared with those that neglect the contact interaction of
the crack faces. Results are presented for different values of the initial crack opening
Presented at the 6th International Conference on Modern Practice in Stress and Vibration Analysis (Bath, United Kingdom, September
5–7, 2006).
Published in Prikladnaya Mekhanika, Vol. 43, No. 7, pp. 125–131, July 2007. 相似文献
16.
V. M. Mirsalimov 《Journal of Applied Mechanics and Technical Physics》2007,48(5):723-733
A mathematical model is constructed for crack nucleation in an isotropic fuel cell (heat-releasing solid material) attenuated
by a biperiodic system of cooling cylindrical channels with a circular cross section. Cracks are assumed to appear with increasing
heat-release intensity in the bulk of the material. The solution of the problem on equilibrium of an isotropic perforated
fuel cell with crack nuclei reduces to the solution of a nonlinear singular integral equation with a Cauchy-type kernel. The
solution of the latter equation yields the forces in the band of crack nucleation. The condition of crack nucleation is formulated
with allowance for the criterion of ultimate extension of bonds in the material.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 121–133, September–October, 2007. 相似文献
17.
In this research, the free vibration analysis of cylindrical shells with circumferential stiffeners, i.e., rings with nonuniform
stiffener eccentricity and unequal stiffener spacing, is investigated using analytical and experimental methods. The Ritz
method is applied in analytical solution, while stiffeners are treated as discrete elements. The polynomial functions are
used for Ritz functions. The effects of nonuniformity of stiffener distribution on natural frequencies are considered for
free–free boundary conditions. Results show that, at constant stiffener mass, significant increments in natural frequencies
can be achieved using nonuniform stiffener distribution. In experimental method, modal testing is performed to obtain modal
parameters, including natural frequencies, mode shapes, and damping in each mode. Analytical results are compared with experimental
ones, showing good agreement. Because of insufficient experimental modal data for nonuniform stiffener distribution, the results
of modal testing obtained in this study could be a useful reference for validating the accuracy of other analytical and numerical
methods for free vibration analysis. 相似文献
18.
Ralf Müller Petia Dineva Tsviatko Rangelov Dietmar Gross 《Archive of Applied Mechanics (Ingenieur Archiv)》2012,82(1):97-110
The anti-plane dynamic problem of a functionally graded piezoelectric plane containing a hole–crack system is treated by a
non-hypersingular traction-based boundary integral equation method. The material parameters vary exponentially in the same
manner in an arbitrary direction. The system is loaded by an incident SH-type wave, and impermeable boundary conditions are
assumed. Using a frequency-dependent fundamental solution of the wave equation, the boundary value problem is transformed
into a system of integro-differential equations along the boundary of the hole and on the crack line. Its numerical solution
yields the dynamic stress intensity factors and stress concentration factors. A parametric study reveals their dependence
on the hole–crack scenario and its geometry, characteristics of the dynamic load and magnitude and direction of material inhomogeneity. 相似文献
19.
V. V. Zozulya 《International Applied Mechanics》2007,43(5):586-590
The contact-interaction problem for a stationary plane crack with friction between its edges under the action of a normal
(to the crack plane) harmonic shear wave is addressed. Antiplane deformation conditions are considered. The distribution of
contact forces and displacement discontinuity of crack edges are studied
Published in Prikladnaya Mekhanika, Vol. 43, No. 5, pp. 138–142, May 2007. 相似文献
20.
S. A. Nazarov M. Specovius-Neugebauer 《Journal of Applied Mechanics and Technical Physics》2006,47(5):714-723
An asymptotic formula is obtained for the total-energy increment during quasistatic growth of a semiin finite crack in an
anisotropic elastic plane under complex loading. It is assumed that the shear loads are much larger than the tearing loads.
The shape of the slightly curved crack was determined using the Griffith criterion in two versions: global and local. It is
shown, in particular, that the first version leads to an improbable result.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 5, pp. 119–130, September–October, 2006. 相似文献