共查询到20条相似文献,搜索用时 15 毫秒
1.
Cheng Pinsan 《Acta Mechanica Sinica》1991,7(3):235-242
In this paper, a nonlocal theory of fracture for brittle materials has been systematically developed, which is composed of
the nonlocal elastic stress fields of Griffith cracks of mode-I, II and III, the asymptotic forms of the stress fields at
the neighborhood of the crack tips, and the maximum tensile stress criterion for brittle fracture. As an application of the
theory, the fracture criteria of cracks of mode-I, II, III and mixed mode I–II, I–III are given in detail and compared with
some experimental data and the theoretical results of minimum strain energy density factor. 相似文献
2.
The limit equilibrium of elastoplastic body is studied under the conditions of a plane problem. The body contains a linear
inclusion, which is rigid but of finite rupture strength. The plastic or prefracture zones develop near the ends of the inclusion
and are modeled by slip cracks along the matrix—inclusion interface. A new interpretation of the boundary conditions is proposed
to solve a model problem for such a composition, and its analytical solution is derived. Two possible mechanisms of local
fracture are considered: (a) fracture of the inclusion and (b) separation of the inclusion. The critical length of the inclusion
is determined. This length together with the elastic and strength parameters of the composition determines the mechanism of
local fracture. The limit loads are found for each mechanism of fracture.
State Academy of Water Industry, Rovno, Ukraine. Translated from Prikladnaya Mekhanika, Vol. 36, No. 7, pp. 123–129, July,
2000. 相似文献
3.
A. N. Guz V. M. Nazarenko V. L. Bogdanov 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(9):1273-1293
A joint approach to the study of two non-classical fracture mechanisms, namely fracture of cracked materials with initial (residual) stresses acting along the crack planes and fracture under compression along parallel cracks, is considered in the framework of three-dimensional linearized solid mechanics. Mathematical statements of problems for pre-stressed solids that contain interacting circular cracks are given. Problems for an infinite solid containing two parallel co-axial cracks and for a space with the periodical set of co-axial parallel cracks as well as for a half-space with near-the-surface crack are solved. Several patterns of loading on the crack faces (normal loading, radial shear and torsion) are considered. The effects of initial stresses on stress intensity factors are analyzed for highly elastic materials with some types of elastic potentials. Formulation of fracture criteria accounting effect of initial (residual) stresses is given. Critical parameters of fracture of solids containing interacting cracks under compression along the cracks are calculated. The influence of geometrical parameters of the problems as well as physical and mechanical properties of materials on these critical parameters is analyzed. 相似文献
4.
A. N. Guz’ 《International Applied Mechanics》1998,34(12):1175-1186
This paper studies the brittle fracture of materials with initial stresses when the stresses act only along the cracks. Dynamic
problems for moving cracks are considered when the plane crack infinite in one direction moves with constant velocity. General
formulas are presented for compressible and incompressible elastic bodies with an arbitrary structure of elastic potentials.
The stresses and displacements are presented as analytical functions of complex variables. Some general relationships may
be used in order to obtain exact information on the singularity order of the crack tip for dynamical problems under consideration
in the general formulation.
Translated from Prikladnaya Mechanika, Vol. 34, No. 12, pp. 3–15, December, 1998. 相似文献
5.
A. N. Guz 《International Applied Mechanics》2011,47(2):121-168
Major results on the mechanics of crack propagation in materials with initial (residual) stresses are analyzed. The case of
straight cracks of constant width that propagate at a constant speed in a material with initial (residual) stresses acting
along the cracks is examined. The results were obtained, based on linearized solid mechanics, in a universal form for isotropic
and orthotropic, compressible and incompressible elastic materials with an arbitrary elastic potential in the cases of finite
(large) and small initial strains. The stresses and displacements in the linearized theory are expressed in terms of analytical
functions of complex variables when solving dynamic plane and antiplane problems. These complex variables depend on the crack
propagation rate and the material properties. The exact solutions analyzed were obtained for growing (mode I, II, III) cracks
and the case of wedging by using methods of complex variable theory, such as Riemann–Hilbert problem methods and the Keldysh–Sedov
formula. As the initial (residual) stresses tend to zero, these exact solutions of linearized solid mechanics transform into
the respective exact solutions of classical linear solid mechanics based on the Muskhelishvili, Lekhnitskii, and Galin complex
representations. New mechanical effects in the dynamic problems under consideration are analyzed. The influence of initial
(residual) stresses and crack propagation rate is established. In addition, the following two related problems are briefly
analyzed within the framework of linearized solid mechanics: growing cracks at the interface of two materials with initial
(residual) stresses and brittle fracture under compression along cracks 相似文献
6.
The effect of the biaxial field of external rock pressure on the deformation of the fracture zone formed by radial cracks
in an elastic-brittle medium is studied. We consider cylindrical charges that are rather thin compared to the diameter of
the explosive borehole. This allows one to exclude the grinding zone from consideration. At the initial moment of time, the
system of emerging cracks originating at the boundary of the circular hole is assumed to be symmetric. To solve the problem,
we use singular integral equations and the fracture criterion σϑ. The propagation trajectories of the system cracks are calculated in the quasistatic approximation in a step-by-step manner
in relation to the parameters of the external compressive stress field. Two ideal variants of loading of the crack system
are analyzed. In the first variant, gaseous detonation products penetrate into cracks, and the pressure in the explosion cavity
and the cracks instantaneously equalizes. In the second variant, gases do not penetrate into the cracks of the system. The
fracture zone is shown to become an ellipse whose long axis is oriented in the direction of the largest compressive stress
in magnitude acting at infinity. The effect of the variants of loading of the crack system on the shape and dimensions of
the deformed fracture zone is evaluated.
Mining Institute, Siberian Division, Russian Academy of Sciences, Novosibirsk 630091. Translated from Prikladnaya Mekhanika
i Tekhnicheskaya Fizika, Vol. 39, No. 1, pp. 129–137, January–February, 1998. 相似文献
7.
V. S. Kirilyuk 《International Applied Mechanics》2006,42(2):152-161
The static equilibrium of an electroelastic transversely isotropic space with a plane crack under antisymmetric mechanical
loads is studied. The crack is located in the plane of isotropy. Relationships are established between the stress intensity
factors (SIFs) for an infinite piezoceramic body and the SIFs for a purely elastic body with a crack of the same form under
the same loads. This makes it possible to find the SIFs for an electroelastic body without the need to solve specific electroelasitc
problems. As an example, the SIFs are determined for a piezoelastic body with penny-shaped and elliptic cracks under shear
__________
Translated from Prikladnaya Mekhanika, Vol. 42, No. 2, pp. 32–42, February 2006. 相似文献
8.
The surface crack is a common flaw in structures and vessels, and its elastic characterization has been studied extensively
as reviewed in Ref. 1 and its references. Elastic-plastic fracture-mechanics (EPFM) technology can be used to characterize
surface cracks in tough materials. Two EPFM aprameters are commonly used: the crack-tip-opening displacement (CTOD) and the
three-dimensionalJ integral. This paper draws on a series of studies2–11 at the National Bureau of Standards related to the development and verification of analyticalmodels for the calculation of
EPFM parameters in surface-cracked tensile panels. The models previously verified for pipeline steel plates4–7 are used to calculate the crack-mouth-opening displacement (CMOD) andJ for surface cracks in welded-steel specimens. 相似文献
9.
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
10.
V. S. Kirilyuk 《International Applied Mechanics》2008,44(10):1106-1118
The static equilibrium of a transversely isotropic magnetoelectroelastic body with a plane crack of arbitrary shape in the
isotropy plane under antisymmetric mechanical loading is studied. The relationships between the stress intensity factors (SIFs)
for an infinite magnetoelectroelastic body and the SIFs for a purely elastic body with the same crack and under the same antisymmetric
loading are established. This enables the SIFs for a magnetoelectroelastic body to be found directly from the analogous problem
of elasticity. As an example of using this result, the SIFs for penny-shaped, elliptic, and parabolic cracks in a magnetoelectroelastic
body under antisymmetric mechanical loading are found
Translated from Prikladnaya Mekhanika, Vol. 44, No. 10, pp. 37–51, October 2008. 相似文献
11.
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.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 158–166, July–August, 2009. 相似文献
12.
The stress-strain state of an incompressible cylindrical elastic body with antiplane strain under the action of potential
forces and surface loading constant along the body is considered in a nonlinear formulation in actual variables. The stresses
are expressed via the pressure and independent strains, the pressure is expressed via the force and elastic potentials, and
nonlinear boundary-value problems are posed for strains (and displacements). Various methods for solving these problems are
developed. For the nonlinear equations obtained, some analytical solutions containing free parameters are given, which can
be used as a basis for solving particular problems.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 6, pp. 93–101, November–December, 2006. 相似文献
13.
V. M. Mirsalimov 《Journal of Applied Mechanics and Technical Physics》2009,50(4):712-719
A plane problem of fracture mechanics for a circular disk fitted onto a rotating shaft is considered. The disk is assumed
to be fitted tightly onto the shaft, and there are N randomly located straight-line cracks of length 2lk (k = 1, 2, ..., N) near the inner surface of the disk. The interference between the disk and the rotating shaft, providing minimization
of fracture parameters (stress intensity factor) of the disk, is theoretically studied on the basis of the minimax criterion.
A closed system of algebraic equations is constructed, which allows the problem of optimal design to be solved. A simplified
method of minimization of disk fracture parameters is considered.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 201–209, July–August, 2009. 相似文献
14.
O. S. Bogdanova 《International Applied Mechanics》2008,44(8):938-945
A modified δc-model is used to study the limiting state of an orthotropic plate weakened by a periodic row of collinear cracks and satisfying
a general failure criterion. The failure mechanism of the plate is analyzed.Astudy is made of the effects of the degree of
orthotropy, the biaxiality of external loading, and the geometrical parameters on the fracture process zones at the crack
tips and the limiting state of the plate. The safe loading of an orthotropic viscoelastic plate with a periodic row of collinear
cracks is examined. The effect of the rheological parameters on the safe-load region is studied
Translated from Prikladnaya Mekhanika, Vol. 44, No. 8, pp. 126–135, August 2008. 相似文献
15.
Hamdy M. Youssef Amnah H. Al-Harby 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(9):675-687
In this work, we will consider an infinite elastic body with a spherical cavity and constant elastic parameters. The governing
equations are taken in the context of the two-temperature generalized thermoelasticity theory (Youssef in J Appl Math Mech
26(4):470–475 2005a, IMA J Appl Math, pp 1–8, 2005). The medium is assumed initially quiescent. Laplace transform and state
space techniques are used to obtain the general solution for any set of boundary conditions. The general solution obtained
is applied to a specific problem when the bounding plane of the cavity is subjected to thermal loading (thermal shock and
ramp-type heating). The inverse Laplace transforms are computed numerically using a method based on Fourier expansion techniques.
Some comparisons have been shown in figures to estimate the effect of the two-temperature and the ramping parameters. 相似文献
16.
V. S. Kirilyuk 《International Applied Mechanics》2008,44(7):757-768
The paper establishes a relationship between the solutions for cracks located in the isotropy plane of a transversely isotropic
piezoceramic medium and opened (without friction) by rigid inclusions and the solutions for cracks in a purely elastic medium.
This makes it possible to calculate the stress intensity factor (SIF) for cracks in an electroelastic medium from the SIF
for an elastic isotropic material, without the need to solve the electroelastic problem. The use of the approach is exemplified
by a penny-shaped crack opened by either a disk-shaped rigid inclusion of constant thickness or a rigid oblate spheroidal
inclusion in an electroelastic medium
__________
Translated from Prikladnaya Mekhanika, Vol. 44, No. 7, pp. 47–60, July 2008. 相似文献
17.
V. D. Kurguzov 《Journal of Applied Mechanics and Technical Physics》2016,57(7):1198-1207
The effect of the mesh geometry on the accuracy of solutions obtained by the finite-element method for problems of linear fracture mechanics is investigated. The guidelines have been formulated for constructing an optimum mesh for several routine problems involving elements with linear and quadratic approximation of displacements. The accuracy of finite-element solutions is estimated based on the degree of the difference between the calculated stress-intensity factor (SIF) and its value obtained analytically. In problems of hydrofracturing of oil-bearing formation, the pump-in pressure of injected water produces a distributed load on crack flanks as opposed to standard fracture mechanics problems that have analytical solutions, where a load is applied to the external boundaries of the computational region and the cracks themselves are kept free from stresses. Some model pressure profiles, as well as pressure profiles taken from real hydrodynamic computations, have been considered. Computer models of cracks with allowance for the pre-stressed state, fracture toughness, and elastic properties of materials are developed in the MSC.Marc 2012 finite-element analysis software. The Irwin force criterion is used as a criterion of brittle fracture and the SIFs are computed using the Cherepanov–Rice invariant J-integral. The process of crack propagation in a linearly elastic isotropic body is described in terms of the elastic energy release rate G and modeled using the VCCT (Virtual Crack Closure Technique) approach. It has been found that the solution accuracy is sensitive to the mesh configuration. Several parameters that are decisive in constructing effective finite-element meshes, namely, the minimum element size, the distance between mesh nodes in the vicinity of a crack tip, and the ratio of the height of an element to its length, have been established. It has been shown that a mesh that consists of only small elements does not improve the accuracy of the solution. 相似文献
18.
Ingrid Ott R. Kienzler R. Schröder 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(5):527-541
It is well known that the material behavior of human cortical bone changes from ductile to more brittle due to aging. This
process is accompanied by a decrease of the maximum specific deformation energy. Numerous mechanical tests of specimens have
shown a relationship between the mechanical behavior, age and microstructure, especially the porosity, mineralization and
fraction of the secondary osteonal area. But up to now, this relationship is not explicitly considered in a constitutive law.
Measured stress–strain curves, taken from the literature, from one-dimensional mechanical experiments in tension (McCalden
et al. in J Bone Joint Surg Am 75(8):1193–1205, 1993) have been characterized by Young’s modulus, elastic, plastic and fracture
energy, fracture stress and strain. The specimens have been harvested from the femora of 46 deceased individuals. Based on
this data, we set up a system of equations taking into account the microstructure of the bone material by analogy to common
procedures in fracture and damage mechanics. Solving this system for all measured experimental data leads to the determination
of the independent damage parameters for each individual person. It turned out that some characteristic mechanical values
and one independent damage parameter are statistically significant dependent on age and microstructure. We receive a constitutive
law, which describes the mechanical behavior up to fracture by measurable parameters for the microstructure and the individual
age and gender only. In turn, we calculate the individual tolerable load for bending, using a nonlinear stress–strain curve,
and postulate an age-dependent fracture load for healthy bone by means of the statistical regression. Deviation from the standard
is an indication for a bone disease in particular for osteoporosis. 相似文献
19.
A. I. Khromov A. A. Bukhan'ko O. V. Kozlova S. L. Stepanov 《Journal of Applied Mechanics and Technical Physics》2006,47(2):274-281
Based on the theory of an ideal rigid-plastic body, an approach is formulated for determining fracture constants on the basis
of standard mechanical tests on uniaxial extension of plane and cylindrical samples. Instead of the experimentally determined
characteristics of fracture of materials (dimensionless elongation and constriction of the sample during its fracture), two
invariant tensor characteristics of the degree of sample deformation are introduced, which correspond to the moment of origination
of a macrocrack and critical strain at the crack tip determining the process of crack propagation.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 2, pp. 147–155, March–April, 2006. 相似文献
20.
Jian Chen 《Archive of Applied Mechanics (Ingenieur Archiv)》2006,75(2-3):138-152
The static and dynamic anti-plane problem for a functionally graded coating–substrate structure containing a periodic array
of parallel cracks, which are perpendicular to the boundary, is considered. Integral-transform techniques are employed to
reduce the problem to the solution of an integral equation with hypersingular kernels. Numerical results are presented to
show the influence of geometry, material properties and material gradient parameter on the fracture behavior. 相似文献