Yu. V. Grinyaev, N. V. Chertova, and M. A. Chertov
Institute of the Physics of Strength and Materials Science, Siberian Division, Russian Academy of Sciences, Tomsk 634021
Pages: 612-616
An equation governing the evolution of
elastic strains (stresses) for a given
strain rate is obtained using the field
theory of defects under the assumption
of uniform defect distribution. Strain
diagrams are constructed by numerical
solution of this equation and
qualitative analysis of the phase
portrait of the corresponding dynamic
system. The effect of strain rate on the
mechanical properties of materials is
studied.
Stability analysis of noncircular shells
is performed with allowance for
nonlinear subcritical deformation.
Explicit expressions for the rigid
displacements of elements of noncircular
cylindrical shells are obtained and used
to construct shape functions of an
effective quadrilateral finite element
of natural curvature. A finite-element
algorithm for solving problems of
nonlinear deformation and stability of
shells is developed. Stability problem
of an elliptic cylindrical shell is
considered. The effect of the
ellipticity and subcritical nonlinear
deformation of the shell on the critical
load is studied. Results obtained are
compared with available experimental
data.
A problem of elastic body deformation
with conditions of dry friction imposed
at the boundary is considered. Various
friction laws are studied, including
linear one-parameter and nonlinear two-
parameter laws. A general view of a
nonlinear function with two constants is
suggested, which determines the friction
force as a function of normal pressure.
The problem of elastic plate compression
by rough infinite plates for a variety
of friction conditions on the contact
surfaces is solved. The plate equations
are employed, which make it possible to
specify arbitrary conditions on the
front faces without reducing the order
of differential equations. The unknown
boundary of ideal contact zones and
sliding zones is determined. Solutions
obtained by using various friction
conditions on the contact surfaces are
compared.
The paper reports results of
experimental studies of stress
concentration in cylindrical samples of
spheroplasts (composites in which the
binder is dianepoxy and the filler is
glass microspheres) with some types of
concentrators and fracture of these
samples under uniaxial compression. We
performed numerical modeling of the
stress
The influence of disbalance of densities
of twinning dislocations at the
boundaries on the stressed state inside
a wedge-shaped twin, near its top, and
in external regions adjoining the
twinning boundary is studied using a
dislocation model.
A profile-genetic classification of soils of technogenous landscapes is proposed. Its hierarchical structure has been worked out. Diagnostic features of types, subtypes, genera and species of soils are shown.
A quantitative estimation of connections in the soil - climate system at regional-ecological, and soil - environment system at topoecological levels is carried out. The ecological niches of formation and functioning of soils of cryoaridical landscapes of Transbaikalia are established.
Inner properties of Khakassia chernozems have been elucidated. Indicators of compressibility and inflection points have been found, and the relations between these parameters have been statistically justified.
The concept of pyrogenesis as a subfactor of automorphic humid mountain taiga pedogenesis in continental sectors of the cryomorphic area of Eurasia is defined. The general peculiarities of weathering and zonal pedogenesis have been recorded in the areas of active pyrogenesis. On the example of cryomorphic soddy-calcareous soil, the quantitative and qualitative changes of its profile form, attributes and composition were revealed within 7 years after a strong ground fire. It has been quantitatively determined that the decrease by 21 cm (100 %) of the fine-earth layer thickness of the soil profile during the postfire period is connected with the burning-out of organic matter of the surface organic horizons at 5.4 cm (or 26 %), the surface destruction of soil fine-earth layer at 5.8 cm (28 %), and with the temperatural subsidence of the fine-earth layer which amounts to 9.8 cm ( 46 % of the general total contribution of factors). At that, according to our data, the maximum temperatural subsidence of fine-earth layer of cryomorphic soils of heavy granulometric composition with icy permafrost can make up 20-30 % of the maximum postfire thickness of their seasonally thawed layer. The average annual depth of the destruction of soil fine-earth layer from the surface of this soil was 0.8 cm according to our data, which is comparable with other authors' data.
On the materials of field studies using the data of remote probing in the southern outskirts of the Great Vasyugan swamp, analysis of spatial distribution of zonal soil-vegetation complexes has been carried out. Materials of the authors' own studies are compared with the literature data on the zonal geographical division of the West Siberian Plain. The results obtained allow specifying the scheme of subzonal soil-geobotanic division within the limits of the taiga zone of West Siberia.
