scholarly journals Complex stress state of materials and structural elements and strength criteria: the scientific business card of Academician A.O. Lebedev

2021 ◽  
pp. 69-76
Author(s):  
Valentin V. Matveev ◽  
◽  
Anatoliy P. Zinkovskii ◽  
Keyword(s):  
Solid Mechanics ◽  
Science And Technology ◽  
Complex Stress ◽  
Complex Stress State ◽  
State Prize ◽  
Structural Elements ◽  
Deformable Solid ◽  
Strength Criteria ◽  
90Th Anniversary ◽  
Ussr State

On February 1, the scientific community celebrates the 90th anniversary of a prominent Ukrainian scientist in the field of deformable solid mechanics, laureate of the USSR State Prize (1982), the State Prize of Ukraine in Science and Technology (1997), Honored Worker of Science and Technology of Ukraine (2001), laureate of S.P. Tymoshenko (2004) and G.S. Pysarenko (2011) Prizes of the NAS of Ukraine, Doctor of Technical Sciences (1972), Professor (1976), Academician of the NAS of Ukraine (1988) Anatoliy O. Lebedev.

scholarly journals Influence of stresses on deformation process under the irradiation creep and swelling

2021 ◽  
pp. 23-28
Author(s):  
Dmytro Breslavsky
Keyword(s):  
Numerical Modelling ◽  
Strain State ◽  
Strain Tensor ◽  
Complex Stress ◽  
Complex Stress State ◽  
Structural Elements ◽  
Stress Strain ◽  
Radiation Creep ◽  
Stress Strain State ◽  
Radiation Swelling

Approaches for describing the deformation of structural elements made from the material, in which radiation creep and swelling strains develop simultaneously, are discussed. The technique for description of irradiation swelling strains, which is used for calculational analysis of stress-strain state arising in structural elements under the joint action of irradiation and thermal-stress fields, is regarded. A complete system of equations of the boundary –initial value problem is presented, in which elastic and thermal strains, strains of radiation creep and swelling are taken into account. Numerical modelling was carried out using the specialized software FEM Creep, in which the boundary value problem is solved by the Finite Element Method, and the initial one is integrated in time by the difference predictor-corrector method. Two forms are given for the equation of state describing the radiation swelling strains: first is for the components of the strain tensor as well as second is prepared for their rates. The hypothesis about the linear correspondence of the received radiation dose and the deformation time, during which radiation swelling strains develop, are analyzed. A number of questions that require answers when using equations with a complex stress state in which the radiation swelling strains are directly depend on stresses, are discussed. Based on the processing of experimental data on the swelling of tubes made of steel 316Ti in the temperature range of 450-460 °С, a form of the equation for the radiation swelling strain rate is proposed, and the constants included in it are determined. Using the example of numerical modelling of the deformation of tubes were made of steel 316Ti and loaded by inner pressure, the applicability of the classical approach for the analysis of the stress-strain state in the presence of radiation swelling strains is shown.

scholarly journals On joint efficiency of composite anisotropic plate rigidly fixed along outside edges

2020 ◽  
Vol 19 (4) ◽  
pp. 304-309
Author(s):  
A. G. Akopyan
Keyword(s):  
Classical Theory ◽  
Solid Mechanics ◽  
Anisotropic Plate ◽  
Composite Plates ◽  
Local Stress ◽  
Operating Conditions ◽  
Structural Elements ◽  
Deformable Solid ◽  
Engineering Structures ◽  
Anisotropic Plates

Introduction. Modern processes of welding, surfacing, soldering and bonding provide producing structural elements of monolithic interconnected dissimilar anisotropic materials. The combination of different materials with qualities corresponding to certain operating conditions offer comprehensive facilities to improve the technical and economic characteristics of machines, equipment and structures. It can contribute to a significant increase in their reliability, durability, and to reduction of the production and operation costs. Materials and Methods. The work objective is to study the boundary state of stress of anisotropic composite plates in the framework of the classical theory of plate bending. The outer edges of the plate are considered free. Using the classical theory of bending of an anisotropic plate in the space of physical and geometric parameters, hypersurface equations are obtained that define low-stressed zones for the contact surface edge of a cylindrical orthotropic composite plate.Research Results. Finding the criteria for engineering structures to determine the limiting strength characteristics of structural elements is one of the urgent tasks of the deformable solid mechanics. Strength problems in structures are often reduced to elucidating the nature of the local stress state at the tops of the joints of the constituent parts. This paper is devoted to solving this problem for composite anisotropic plates in the area of their bending.Discussion and Conclusions. The solution proposed in this paper may be useful for increasing the strength of composite products.

scholarly journals Keeper of the world's largest radio telescope (in-terview to the 70th anniversary of Academician of the NAS of Ukraine O.O. Konovalenko)

2021 ◽  
pp. 89-100
Author(s):  
Olexander O. Konovalenko ◽  
Keyword(s):  
Radio Astronomy ◽  
Science And Technology ◽  
Low Frequency ◽  
70Th Anniversary ◽  
State Prize ◽  
National Academy Of Sciences ◽  
Ussr State ◽  
And Mathematics ◽  
Academy Of Sciences

February 27 marks the 70th anniversary of the famous scientist in the field of radio astronomy and astrophysics, laureate of the State Prize of Ukraine in Science and Technology (2018), laureate of the USSR State Prize (1988), Honored Worker of Science and Technology of Ukraine (2001), laureate of the NAS of Ukraine Prizes named after S.Ya. Braude (2008) and M.K. Yangel (2013), Head of the Department of Low-Frequency Radio Astronomy, Deputy Director of the Radio Astronomical Institute of the NAS of Ukraine (since 2007), Doctor of Physics and Mathematics (1984), Academician of the NAS of Ukraine (2003) Olexander O. Konovalenko. Taking the opportunity, the editorial board of the Visnyk of the National Academy of Sciences of Ukraine interviewed Academician O.O. Konovalenko and asked about his path in science, his greatest achievements and plans for the future.

scholarly journals On application of a linear fractional creep and creep rupture strength model in simulation of long-term destruction of typical structural elements in an active medium

2020 ◽  
pp. 89-96
Author(s):  
Леонид Викторович Фомин
Keyword(s):  
Active Medium ◽  
Rupture Strength ◽  
Complex Stress ◽  
Average Concentration ◽  
Complex Stress State ◽  
Structural Elements ◽  
The Times ◽  
Integral Average ◽  
Fracture Processes

Исследуется длительное разрушение оболочки и пластины при ползучести в активной среде в условиях нестационарного сложного напряженного состояния. Учет влияния среды на время до разрушения осуществляется с помощью введения в определяющие и кинетические дробно-линейные соотношения функции от интегрально средней концентрации среды. Проведено сравнение времен до разрушения при использовании скалярного и векторного параметров поврежденности. Определены особенности использования дробно-линейной модели для описания процессов длительного разрушения. The long-term destruction of the shell and plate during creep in the active medium under the conditions of an unsteady complex stress state is investigated. The influence of the medium on the time to fracture is taken into account by introducing a function of the integral average concentration of the medium into the constitutive and kinetic linear-fractional relationships. Comparison of the times to failure using the scalar and vector damage parameters is carried out. The features of using a linear-fractional model to describe long-term fracture processes are determined.

scholarly journals The path to scientific heights (to the 90th anniversary of Academician of NAS of Ukraine S.V. Peletminskii)

2021 ◽  
pp. 77-82
Author(s):  
Oleksandr S. Bakai ◽  
◽  
Yurii V. Slyusarenko ◽  
Nikolay F. Shul’ga ◽  
◽  
...  
Keyword(s):  
Statistical Physics ◽  
Science And Technology ◽  
Theoretical Physics ◽  
State Prize ◽  
Quantum Liquid ◽  
Science Center ◽  
National Science ◽  
90Th Anniversary ◽  
Theoretical Physicist ◽  
And Mathematics

February 14 marks the 90th anniversary of the outstanding Ukrainian theoretical physicist in the field of statistical physics, quantum liquid and crystal physics, plasma physics, magnetic phenomena, quantum field theory, whose work is recognized by the world scientific community, twice winner of the State Prize of Ukraine in Science and Technology (1986, 1996), Honored Worker of Science and Technology of Ukraine (1998), winner of the nominal prizes of the NAS of Ukraine named after K.D. Synelnykov (1978), M.M. Krylov (1986), M.M. Bogolyubov (2002), O.I. Akhiezer (2018), Chief Researcher at the Institute of Theoretical Physics of the National Science Center Kharkov Institute of Physics and Technology, Doctor of Physics and Mathematics (1966), Professor (1969), Academician of the NAS of Ukraine (1990) Sergey V. Peletminskii.

Comparison of strength criteria of rock under complex stress state

2014 ◽  
pp. 715-720 ◽  
Author(s):  
H Li ◽  
H Liao ◽  
J Ren ◽  
G Xiong ◽  
G Zhao ◽  
...  
Keyword(s):  
Stress State ◽  
Complex Stress ◽  
Complex Stress State ◽  
Strength Criteria

Issues of further development and improvement of design standards for wood structures

2019 ◽  
pp. 35-41
Keyword(s):  
Complex Stress ◽  
Complex Stress State ◽  
Internal Stresses ◽  
Design Standards ◽  
Duration Of Action ◽  
Wood Structures ◽  
Strength Criteria ◽  
Current State ◽  
Wooden Structures ◽  
Further Development

The current state of design of wooden structures against the background of the historical development of design standards is analyzed, the tasks of their further development are formulated. The strength criteria ensuring progress in the design of unique and spatial wooden structures are considered. Examples of unique large-span coatings, principles of their design with providing a spatial scheme are presented. In addition, the methodology for the nonlinear analysis of such systems with due regard for the duration of action of the load and of redistribution of internal stresses, especially under unsymmetrical loads, including with due regard for the coverings between the ribs experiencing a complex stress state is proposed. The application of the calculation method considered provides material savings and at the same time increases the reliability and survivability of the structure. Some possible additions and proposals on the structure and content of the new version of the norms are proposed. Taking into account continuity and achievements of the technical progress the necessity of development of new standards on the basis of advanced technologies of production, design and calculation of designs on the computer is proved.

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