https://www.elibrary.ru/title_about_new.asp?i
1605-8119
Materials physics and mechanics
7
1
2004
1-78
RAR
RUS
1-8
Nagase
Kawahara
kawahara@kuaero.kyoto-u.ac.jp
Chaotic Breathers in a Nonlinear Beam Lattice Model
Dynamical behaviours of chaotic breathers are investigated numerically for a one-dimensional nonlinear beam lattice model involving rotational degree of freedom in addition to the well-known FermiPasta-Ulam-β (FPU-β) lattice. Evolutions of the initial disturbances composed of the highest wavenumber mode are pursued numerically to observe generation, propagation, and an eventual decay of the localized structure (chaotic breather). Detailed numerical analyses are done for the FPU-β lattice so as to compare with the beam lattice model. Initial localization process is discussed based on the modulational instability theory. Dynamical evolutions of displacemment, rotation, energy, wavenumber spectra etc. are observed and an attempt is made to understand qualitatively the entire evolution process. It is found that the inclusion of the rotation enhances either generation or decay processes of the chaotic breathers in comparison with the case of the FPU-β lattice.
Nonlinear Beam Lattice Model
Chaotic breathers
FermiPasta-Ulam-β lattice
FPU-β lattice
https://mpm.spbstu.ru/article/2004.9.1/
MPM_7_1_P01.pdf
RAR
RUS
9-16
Pastrone
franco.pastrone@unito.it
Cermelli
paolo.cermelli@unito.it
Porubov
porubov@math.ioffe.ru
Nonlinear Waves in 1-D Solids with Microstructure
A general model of one-dimensional body with a scalar microstructure is introduced. Field equations are obtained via a variational principle, as Euler-Lagrange equations of a suitable energetic functional. The evolution of finite amplitude strain solitary waves is studied, taking into account both micro and macro dissipations. The formation, propagation and attenuation/amplification of bell-shaped and kink-shaped waves is proved. For a very simple form of the modal equation, the nonlinearity in the microlevel leads to a complicated term in the equation of motion and opens up direct ways for determining material constants characterizing the microstructure.
Nonlinear Waves
1-D Solids
Microstructure
https://mpm.spbstu.ru/article/2004.9.2/
MPM_7_1_P02.pdf
RAR
RUS
17-22
Buzjurkin
buzjura@itam.nsc.ru
Kiselev
Powder Compaction in the Axisymmetric Case
The interaction between shock waves in porous and powdered materials remains a important research area. This importance stems from the necessity of establishing optimum loading conditions for obtaining compacts with spatially uniform physical and mechanical properties. The present consideration shows that an increase in the decay time of the external pressure achieved either through increasing the explosive thickness or through increasing the value of the external load causes no decrease in the dimensions of the fractured region under a fixed value of detonation velocity. At the same time, as the propagation velocity of the detonation wave decreases, the fractured region shrinks substantially.
Powder Compaction
Axisymmetric Case
https://mpm.spbstu.ru/article/2004.9.3/
MPM_7_1_P03.pdf
RAR
RUS
23-28
Fomin
Kraus
kraus@itam.nsc.ru
Ivan I. Shabalin
An Equation of State for Condensed Matter behind Intense Shockwaves
Thermodynamic functions that realistically describe characteristics of substances in various parts of the phase diagram are fundamental characteristics of matter. The necessity in such functions has always been urgent and permanently increases. The advanced equations of state constructed to describe the behavior of metals in a broad range of compression parameters contain tens of free parameters and experimentally found constants (see, for instance, [1, 2]). Such constants were found from shock-wave data, from measured unloading isentropes of porous specimens, and from other experimental thermodynamic data. In the present paper, we propose new model equations for thermodynamic functions of crystalline and liquid states based on the dependence of the Gruneisen coefficient Γ(V, T) on volume and temperature. The difference between the elastic (“cold”) components of energy and pressure for a liquid and those for a solid is taken into account. Configurational entropy of a liquid, providing a measure of its disorder and resulting in finite values of the total entropy in the zero-temperature limit, is introduced.
Equation of State
Condensed Matter
Shockwaves
https://mpm.spbstu.ru/article/2004.9.4/
MPM_7_1_P04.pdf
RAR
RUS
29-36
Knyazeva
Institute of Strength Physics and Materials Science
Tomsk, Russia
Model of Medium with Diffusion and Internal Surfaces and some Applied Problems
This work connects with the modeling of irreversible processes in deformable medium: heat- , masstransfer, physical-chemical conversions in the medium containing the structure heterogeneities. The basic idea consists in the introduction of new thermodynamical variables to describe of structure features of medium and their influence on the irreversible processes. The key definitions and determining correlations are adduced. Some simple examples are presented. The applied problems, where this thermodynamical theory could be used, are discussed.
Model of Medium
Diffusion
Internal Surfaces
https://mpm.spbstu.ru/article/2004.9.5/
MPM_7_1_P05.pdf
RAR
RUS
37-44
Kolpakov
jaroslav@morion.com.ru
The Two-dimensional Analysis of Thickness-shear Vibrations of a Convex-convex Quartz Plates
Low frequency piezoelectric quartz crystals working on the first overtone of thickness-shear mode are popular sources of a precious and highly stable frequencies. The analysis of such crystals is more complicated compared to flat crystals. Usually the energy trapping method is used instead of full three-dimensional analysis. In this paper the new theory of shells [1] is employed. The crystal plate is assumed to be a symmetrical shell. Two-dimensional anisotropic material tensors are obtained. Mode shape of the fundamental harmonic and anharmonic overtones are numerically calculated.
Thickness-shear Vibrations
Two-dimensional Analysis
Convex-convex Quartz Plates
https://mpm.spbstu.ru/article/2004.9.6/
MPM_7_1_P06.pdf
RAR
RUS
45-53
Merlini
merlini@aero.polimi.it
Morandini
morandini@aero.polimi.it
On the Modeling of Elastic Solids by Using Orthonormal Dual Tensors
A new modeling of elastic solids capable of polar description is presented. The primary d.o.f. of a material particle is the rototranslation as a whole. By resorting to the algebra of dual numbers, the rototranslation is represented by an orthonormal dual tensor that inherits all the properties of the rotation. A variational formulation fit for the proposed modeling is outlined and reduced to the case of non-polar materials. The discrete problem exploits consistent multiplicative interpolation and updating technique of the kinematical field. The first results of the finite-element implementation concern simulations of high geometrical nonlinearities in bending dominated problems.
Elastic Solids
Modeling
Orthonormal Dual Tensors
https://mpm.spbstu.ru/article/2004.9.7/
MPM_7_1_P07.pdf
RAR
RUS
54-60
Utkin
Golovnev
Fomin
Molecular-dynamics Simulation of Processes in 3-D Solid Explosives
An important fundamental problem is the study of processes in reacting condensed media and, in particular, the study of detonation phenomena in solid explosives. Experimental studies of chemical reactions and the structure of detonation and shock waves (including that at the micro- and mesoscale) face significant difficulties caused, first, by high intensity of these waves and, second, by the scales of these phenomena in time (nanoseconds) and space (from 10 to 100 ◦ A). At the moment, there is no rigorous kinetic theory of phenomena in solid explosives in the presence of chemical reactions. In this connection, the molecular-dynamics method remains the only adequate research tool that allows one to resolve the fine spatial structure of wave phenomena in such systems and provides the most exhaustive information about them (a set of generalized coordinates and momenta of all atoms). These data, if adequately averaged over mesoscale volumes in which local thermodynamic equilibrium is assumed, should yield continuum-approach parameters. This offers a means for verification of the applicability of main conservation equations, written either in the most general integral form or in the stationary form for the entire computation domain (including the undisturbed region of the crystal, the reacting zone, and the detonation products), to detonating solid explosives [1]. Also of considerable interest is comparison of molecular-dynamics data with the predictions of the continuum theory of detonation, including verification of the Chapman-Jouguet condition. It is the detailed examination of this point that the present work is aimed at. As the physical system, we consider a three-dimensional hypothetical molecular crystal in which exothermic reactions are possible. The reaction was initiated by an impulse of an external force applied to the left side of the crystal and acting on it during a certain time interval, τc = 2·10−13 s. In the numerical experiment, the crystal was placed in an adiabatic shell that restricted the dispersion of detonation products in the plane normal to the propagation direction of the detonation wave. This variant is of interest because it makes it possible to reduce the three-dimensional problem in its present formulation to a one-dimensional problem of the continuum theory of detonation.
Molecular dynamics simulation
3-D Solid
https://mpm.spbstu.ru/article/2004.9.8/
MPM_7_1_P08.pdf
RAR
RUS
61-66
Svistkov
svistkov@icmm.ru
Modeling of Phase Separation in Polymer Solutions during Polymeric Gel Formation
The phase equilibrium in a polymer gel consisting of two phases, of which one involves the polymer network formed through crosslinking of polymer chains (gel-phase of the material) and the other represents a solution of noncrosslinked polymer chains in the mixture of low-molecular fluids is studied. In this work, a model capable of describing the phase separation in the polymer gel at the stage of its formation is proposed. The model takes into account the original composition of solution, the degree of polymerization of polymer chains at the moment of their attachment to the gel-phase, the change in the volume of a polymer network as it swells, the variation in the length of the statistic segment of a polymer chain (Khuns segment) as the mixture composition changes.
Polymer Solutions
Phase Separation
Modeling of Phase Separation
Polymeric Gel Formation
https://mpm.spbstu.ru/article/2004.9.9/
MPM_7_1_P09.pdf
RAR
RUS
67-71
Ievlev
The Voronezh State Technical University
Voronezh, Russia
Shvedov
The Voronezh State Technical University
Voronezh, Russia
Merkulov
The Voronezh State Technical University
Voronezh, Russia
On the Nature of Layer Substructure of Doped Silicon Films
In the paper the mechanism of the formation of the layer substructure of As-doped crystallites of poly-Si films, formed during pyrolysis of silane, is discussed. It is shown that the possibility of the layer substructure formation is controlled by the process of surface diffusion of As atoms over the surface of the growing Si grain.
Silicon
Films
Layer Substructure
https://mpm.spbstu.ru/article/2004.9.10/
MPM_7_1_P10.pdf
RAR
RUS
72-78
Shesterikov
Moscow State Lomonosov University
Moscow, Russia
Beliakova
Moscow State Lomonosov University
Moscow, Russia
Voshedchenko
Federal State United Organization “Krasnaiya Zvezda”
Moscow, Russia
Kashelkin
Federal State United Organization “Krasnaiya Zvezda”
Moscow, Russia
Kuznetsova
Federal State United Organization “Krasnaiya Zvezda”
Moscow, Russia
Yakovlev
Federal State United Organization, Central Scientific Investigation Institute “Prometei”
St.Petersburg, Russia
Long-term Strength Prediction for Chromium-Nickel Austenitic Steels Based on Short-term Experimental Results
A method is proposed for the long-term strength predictions for chromium-nickel austenitic steels based on short-term experimental tests. The experimental data consists of a series of creep diagrams for various applied stresses and temperatures, as well as of the tentative values of the failure time. The long-term strength and creep experiments are illustrated by the results for the steel 08X16H11M3. The metallographical studies of the samples tested in long-term strength and creep experiments are carried out. The microstructure of the deformed sample metal and the failure nature are analysed for various temperature regimes.
Chromium-Nickel Austenitic Steels
Strength
https://mpm.spbstu.ru/article/2004.9.11/
MPM_7_1_P11.pdf