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1.
S. E. Alexandrov E. A. Lyamina 《Journal of Applied Mechanics and Technical Physics》2005,46(6):883-890
The following two models of the plasticity theory are considered: the model with the Mohr-Coulomb yield criterion and the
classical model of the plasticity theory with a yield criterion independent of the mean stress. The deformation problem of
a plastic layer enclosed between two rotating plates is studied.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 6, pp. 136–145, November–December, 2005. 相似文献
2.
V. V. Alekhin B. D. Annin V. V. Ostapenko 《Journal of Applied Mechanics and Technical Physics》2008,49(4):580-586
The Cauchy problem of propagation of plastic state zones in a boundless medium from the boundary of a convex surface, along
which normal pressure and shear forces act, is considered. In the case of complete plasticity, the Tresca system of quasi-static
equations of ideal plasticity, which describes the stress-strain state of the medium, is known to be hyperbolic and to be
similar to a system that describes a steady-state flow of an ideal incompressible fluid. This system is numerically solved
with the use of a difference scheme applied for hyperbolic systems of conservation laws. Results of numerical calculations
are presented.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 4, pp. 74–80, July–August, 2008. 相似文献
3.
G. Bodovillé 《Archive of Applied Mechanics (Ingenieur Archiv)》2002,72(4-5):266-278
Summary Criteria for a priori recognition of the type of steady-state response induced by cyclic loads and prediction whether a structure
will shakedown elastically or not, without the necessity of performing a step-by-step full analysis, have considerable importance.
Melan and Koiter theorems provide criteria that guarantee whether elastic shakedown occurs or not under cyclic loads in case
of perfect plasticity. However, there remain some aspects of the shakedown theory which deserve further study. One of these,
concerned with more realistic nonassociative elastic–plastic constitutive material models, allowing for nonlinear kinematic
and isotropic hardening suitable to describe the cyclic plastic behaviour of metallic materials, has strong motivation. Koiter's
elastic nonshakedown theorem is reconsidered here, with the objective of extending it to the de Saxcé's implicit standard
material class, which contains a wide class of nonassociative elastic–plastic material behaviours. Shakedown analysis is formulated
by a kinematic approach based on the plastic accumulation mechanism concept due to Polizzotto. A sufficient condition for
elastic nonshakedown and a distinct necessary condition are established. Then, an upper bound to the shakedown multiplier
is evaluated.
Received 15 February 2001; accepted for publication 18 October 2001 相似文献
4.
This work provides insight into aspects of classical Mises–Hill plasticity, its extension to the Aifantis theory of gradient
plasticity, and the formulations of both theories as variational inequalities. Firstly, it is shown that the classical isotropic
hardening rule, which is dissipative in nature, may equally well be characterized via a defect energy—and, what is striking,
this energetically based hardening rule mimics dissipative behavior by describing loading processes that are irreversible.
A second aspect concerns the equivalence between the conventional form of the flow rule and its formulation in terms of dissipation.
This equivalence has been previously established using the tools of convex analysis (cf., e.g., Han and Reddy, Plasticity:
mathematical theory and numerical analysis, Springer, New York, 1999)—in the current work this equivalence is derived directly
from the constitutive equations and the specific form of the dissipation, without recourse to such machinery. Variational
inequalities corresponding to the dissipative and energetic forms of the flow rule are derived; these inequalities involve
only the displacement and plastic strain and are well suited to computational studies. Finally, it is shown that the framework
developed for the classical theory is easily extended to incorporate the gradient-plasticity theory of Aifantis (Trans ASME
J Eng Mater Technol 106:326–330, 1984).
相似文献
5.
B. D. Reddy 《Continuum Mechanics and Thermodynamics》2011,23(6):527-549
A general set of flow laws and associated variational formulations are constructed for small-deformation rate-independent
problems in strain-gradient plasticity. The framework is based on the thermodynamically consistent theory due to Gurtin and
Anand (J Mech Phys Solids 53:1624–1649, 2005), and includes as variables a set of microstresses which have both energetic and dissipative components. The flow law is
of associative type. It is expressed as a normality law with respect to a convex but otherwise arbitrary yield function, or
equivalently in terms of the corresponding dissipation function. Two cases studied are, first, an extension of the classical
Hill-Mises or J
2 flow law and second, a form written as a linear sum of the magnitudes of the plastic strain and strain gradient. This latter
form is motivated by work of Evans and Hutchinson (Acta Mater 57:1675–1688, 2009) and Nix and Gao (J Mech Phys Solids 46:411–425, 1998), who show that it leads to superior correspondence with experimental results, at least for particular classes of problems.
The corresponding yield function is obtained by a duality argument. The variational problem is based on the flow rule expressed
in terms of the dissipation function, and the problem is formulated as a variational inequality in the displacement, plastic
strain, and hardening parameter. Dissipative components of the microstresses, which are indeterminate, are absent from the
formulation. Existence and uniqueness of solutions are investigated for the generalized Hill-Mises and linear-sum dissipation
functions, and for various combinations of defect energy. The conditions for well-posedness of the problem depend critically
on the choice of dissipation function, and on the presence or otherwise of a defect energy in the plastic strain or plastic
strain gradient, and of internal-variable hardening. 相似文献
6.
Wei-Yang Lu 《Experimental Mechanics》1986,26(3):224-229
An experimental study of the inelastic behavior of annealed aluminum alloy 6061-T6 tubular specimens subjected to combined
axial and torsional stress cycles is presented. Particular attention is paid to the question of how plastic strain is developed
and how the yield surface moves along the 90-deg out-of-phase stress cycle. Experimental results agree qualitatively with
the predictions of the two-surface plasticity theory.
Paper was presented at the 1985 SEM Spring Conference on Experimental Mechanics held in Las Vegas, NV on June 9–14, 1985. 相似文献
7.
Summary The present study analyzes elasto–plastic thermal stresses in some particle-reinforced functionally graded material plates
(FGP) by taking into consideration residual stresses of the fabrication process. For the FGP, the region near the cooling
metal surface consists of distributed ceramic particles in a metal matrix, while the region near the heating ceramic surface
contains distributed metal particles in a ceramic matrix. We use the thermo–elasto–plastic constitutive equation of a particle-reinforced
composite, taking into consideration temperature changes and damage as well as the reinforcing effect of particles. Elasto–plastic
thermal stresses are discussed here with the goal of reducing the thermal stresses. Two kinds of particle-reinforced FGP are
considered: the first kind (FGP1) represents distributed ceramic particles in the metal matrix, and the second one (FGP2)
represents distributed metal particles in the ceramic matrix. We modify the thermo–elasto–plastic constitutive equation of
a particle-reinforced composite for the FGP2 by taking into consideration temperature changes and damage as well as the reinforcing
effect of particles. Using the temperature-dependent material properties, three cases of temperature conditions are studied.
The first one is the cooling from the fabrication temperature to the room temperature, the second one is the heating from
the room temperature, and the last one is the heating after cooling from the fabrication temperature. The particle volume
fraction is assumed to vary according to a power function in the thickness direction of the FGPs. Using the finite element
method, the effects of the distribution parameter of the composition on the macroscopic stress, the stress in the matrix and
the stress in the particle in the FGPs are discussed. Also, the effects of the particle volume fraction and the fabrication
temperature on the maximum tensile matrix stress are discussed.
Received 22 November 2000; accepted for publication 24 April 2001 相似文献
8.
Eric Loomis 《Shock Waves》2009,19(5):423-432
A recent model based on full elastic anisotropy and crystal plasticity predicted the existence of multiple wave configurations
during the interaction of stress waves with grain boundaries. Since the multiple wave configuration scenario cannot exist
in nature, the principle of minimum entropy production is applied in the current work to find the most probable configuration.
A large amplitude transmitted quasi-longitudinal wave is predicted for the given bicrystal orientation studied due to the
wave propagating near a [001] direction and thus requiring large stress given the very low Schmid factor in this direction
(for nickel aluminide (NiAl) as a model material). Anisotropic elastic–plastic velocity surfaces for quasi-longitudinal and
quasi-shear waves in NiAl have also been constructed to gain an understanding of the general nature of plastic waves as a
function of crystallographic direction. 相似文献
9.
I. Yu. Tsvelodub 《Journal of Applied Mechanics and Technical Physics》1999,40(4):719-726
We study an inverse elastoplastic problem of determining the residual stresses, the plasticity zone, and the external loads
for a plate for known residual deflections which occur after removal of these loads and elastic unloading. Assuming that the
deformation theory of plasticity is valid at the active stage of deformation, we prove the theorem of unique solution. An
iterative method of solution is proposed and a variational formulation of the problem is given. Some simple examples are considered.
Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 4, pp. 186–194, July–August, 1999. 相似文献
10.
A new elastic–plastic impact–contact model is proposed in this paper. By adopting the principle of minimum acceleration for
elastic–plastic continue at finite deformation, and with the aid of finite difference method, the proposed model is applied
in the problem of dynamic response of a clamped thin circular plate subjected to a projectile impact centrally. The impact
force history and response characteristics of the target plate is studied in detail. The theoretical predictions of the impact
force and plate deflection are in good agreements with those of LDA experimental data. Linear expressions of the maximum impact
force/transverse deflection versus impact velocity are given on the basis of the theoretical results.
The project supported by the National Natural Science Foundation of China (10532020). 相似文献
11.
Gradient plasticity theories are of utmost importance for accounting for size effects in metals, especially on the grain scale. Today, there are several methods used to derive the governing equations for the additional degrees of freedom in gradient plasticity theories. Here, the equivalence between an extended principle of virtual power and an extended energy balance is shown. The energy balance of a Boltzmann continuum is supplemented by contributions based on a scalar-valued degree of freedom. It is considered to be invariant with respect to a change of observer. This yields unambiguously the existence of a corresponding micro-stress vector, which is presumed from the outset in the context of an extended principle of virtual power. A thermodynamically consistent nonlocal evolution equation for the additional, scalar-valued degree of freedom is obtained by evaluation of the dissipation inequality in terms of the Clausius–Duhem inequality. Partitioning the nonlocal flow rule yields a partial differential equation, often referred to as micro-force balance. The approach presented is applied to derive a slip gradient crystal plasticity theory regarding single slip. Finally, the distribution of the plastic slip is exemplified with respect to a laminate material consisting of an elastic and an elastoplastic phase. 相似文献
12.
Experimental evidence for length scale effects in plasticity has been provided, e.g., by Fleck et al. (Acta Metall. Mater.
42:475–487, 1994). Results from torsional loadings on copper wires, when appropriately displayed, indicated that, for the
same shear at the outer radius, the normalized torque increased with decreasing specimen radius. Modeling of the constitutive
behavior in the framework of micropolar plasticity is a possibility to account for length scale effects. The present paper
is concerned with this possibility and deals with the theory developed by Grammenoudis and Tsakmakis (Contin. Mech. Thermodyn.
13:325–363, 2001; Int. J. Numer. Methods Eng. 62:1691–1720, 2005; Proc. R. Soc. 461:189–205, 2005). Both isotropic and kinematic
hardening are present in that theory, with isotropic hardening being captured in a unified manner. Here, we discuss isotropic
hardening composed of two parts, responsible for strain and gradient effects, respectively. 相似文献
13.
As a simplified structural model, a semicircular frame is used to study the crashworthiness behavior of an aircraft fuselage. The quasi-static large elastic-plastic deformation of a semicircular frame in the process of its being pressed against a rigid ground is analyzed. First, based on the linear elastic assumption, the quasi-static large deformation contact process of the frame can be divided into three phases, i.e., point contact, line contact and post-buckling. By means of a shooting method, the relations between the displacement and contact force as well as the distribution of bending moment in the three phases are obtained. Then, by assuming an elastic, perfectly-plastic moment-curvature relationship for the semi-circular frame, the contact process is analyzed in detail to reveal the plastic collapse mechanism, the traveling of plastic hinge and the force-displacement relationship. In order to verify the analysis, a preliminary experiment was conducted, in which two types of half rings with clamped ends were pressed by a rigid plate. In addition, a numerical simulation is also conducted by employing ABAQUS to analyze both rectangular cross-sectional beam and I-beam. Finally, the theoretical predictions are compared with the experimental results and numerical solutions, showing that the elastic-plastic analysis can predict the contact process very well. 相似文献
14.
R. A. Abirov 《Journal of Applied Mechanics and Technical Physics》2009,50(1):107-111
A model of plasticity for a transversely isotropic material with allowance for complex loading is developed, based on results
of experiments with homogeneous cylindrical specimens of isotropic materials. An empirical model of plasticity for isotropic
metals is constructed with allowance for vector properties of the material. The model is extended to a particular case of
anisotropy.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 1, pp. 128–133, January–February, 2009. 相似文献
15.
The hydraulic and mass transfer characteristic of a novel grid-structured plastic packing is presented. The geometry of this
structured packings differ substantially from conventional corrugated structured packings resulting in an open structure which
enables a free exchange of vapour and liquid also in horizontal direction. The hydraulic performance has been measured by
air–water experiments in a 440 mm diameter column, the mass transfer characteristic has been determined with the absorption
system ammonia–air–water. Is is shown that the grid-structured plastic packing is highly efficient, particularly in terms
of the hydraulic capacity compared with random plastic packings. Beside this, the main advantage of the packing is the easy
handling and installation as well as the low investment costs compared to the well-known conventional corrugated structured
packings. 相似文献
16.
A symmetric problem of elasticity is formulated to analyze the plastic zone at the corner point of the interface between two
isotropic media. The piecewise-homogeneous isotropic body with an interface in the form of angle sides consists of different
elastic parts joined by a thin elastoplastic layer. The plastic zone is modeled by discontinuity lines of tangential displacement,
which are located at the interface. The exact solution of the problem is found using the Wiener–Hopf method and is then used
to determine the length of the plastic zone. The stress at the corner point is analyzed
Translated from Prikladnaya Mekhanika, Vol. 45, No. 2, pp. 59–69, February 2009. 相似文献
17.
T. M. Poletika S. V. Kolosov G. N. Narimanova A. P. Pshenichnikov 《Journal of Applied Mechanics and Technical Physics》2006,47(3):426-432
Regular features in plastic-strain macrolocalization are examined at the parabolic stage of strain hardening in the é635 and
Zircaloy-2 zirconium alloys. Instability of the plastic flow is observed, which is manifested as a periodic variation of space-time
distributions of local strain as revealed by means of speckle interferometry. The data obtained are discussed within the framework
of a synergetic model for the plastic flow evolution at the final stage.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 141–149, May–June, 2006. 相似文献
18.
A. A. Kaminskii L. A. Kipnis V. A. Kolmakova G. A. Khazin 《International Applied Mechanics》2000,36(3):372-376
The paper deals with calculation of a plastic zone near a crack tip in a homogeneous elastoplastic solid and near a corner
point of the boundary of this solid. The calculations are conducted for a solid subject to plane strain and within the framework
of models with plastic strips. It is shown that in comparison with the widely used model with two straight slip-lines, the
process of plastic deformation is described by the “trident” model more accurately. The results of calculations of the plastic
zone by the “trident” model that correspond to different stages of the development of plastic deformation are given for a
crack of normal separation in a quasibrittle material.
S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika,
Vol. 36, No. 3, pp. 95–100, March, 2000. 相似文献
19.
20.
V. M. Greshnov I. V. Puchkova 《Journal of Applied Mechanics and Technical Physics》2010,51(2):280-287
This paper deals with mathematical modeling of one of the effective technologies of plastic metal forming — multistep cold
metal forging. Experimental results are given on the plastic behavior of metals under cyclic loading at large strains accumulated
for one cycle. Based on the experimental data obtained, a plasticity model is developed and shown to be effective in testing
and improving the technology of forging a nut blank by using a computer-aided engineering analysis system. 相似文献