Vol 9, No 2-4 (2015)
- Year: 2015
- Articles: 20
- URL: https://journals.eco-vector.com/2074-0530/issue/view/3723
Articles
5-8
Vstrechi s moim uchitelem V.V. Novozhilovym
Izvestiya MGTU MAMI. 2015;9(2-4):9-11
9-11
Pamyati V.V. Novozhilova
Izvestiya MGTU MAMI. 2015;9(2-4):11-12
11-12
Long-term strength criterion based on V. V. Novozhilov concept of loosening
Abstract
The kinetic equation for the rate of creep parameter of continuity and long-term strength criterion was formulated on the basis of experimental studies results of density changes in high-temperature creep of metals and taking into account the law of conservation of mass. A comparative analysis of obtained solutions with the relevant results was made according to Kachanova-Rabotnova concept of damage.
Izvestiya MGTU MAMI. 2015;9(2-4):13-18
13-18
Criteria for long-term strength of compressible viscoelastic medium aging
Abstract
The paper considers problem of damage and long-term strength of polymeric and composite materials with a ductile-brittle mechanical properties. The modified Maxwell equation written in the scale of the effective time and Boltzmann-Volterra equation of hereditary viscoelasticity are used. Parameter of continuity (of damage) is determined by the relative changes of density, which is an integral measure of the accumulation of structural microdefects in the long process of loading. The kinetic equation for continuity parameter is formulated and interrelated system of equations of creep and damage is analyzed. Analytical relations for creep, continuity parameter and criteria of long-term strength are obtained.
Izvestiya MGTU MAMI. 2015;9(2-4):19-24
19-24
Preliminary tension as a way to reduce damage accumulation under cyclic loading
Abstract
The article shows how, by changing cycle asymmetry factor using prestress, it is possible significantly increase the fatigue strength of parts or even eliminate its fatigue failure, which is especially valuable for the consumable components of safety devices.
Izvestiya MGTU MAMI. 2015;9(2-4):25-33
25-33
Elements of nonlinear continuum mechanics in the modern theory
Abstract
The theoretical advancement in the field of modern nonlinear continuum mechanics is discussed. The paper includes elements of the mathematical apparatus, development of the foundations of a General tensor theory of mechanical processes and their representations, including generalization of concepts of objective derivatives and integrals, concepts of tensor measures of stresses and deformations, new approaches in theory of the resistance of solids to deformation.
Izvestiya MGTU MAMI. 2015;9(2-4):34-43
34-43
Deformation characteristics of aluminum alloys
Abstract
The paper presents the results of tests to failure of aluminum alloys samples AMg6, AMg6M of various forms. Among the samples there were uniaxial samples, tubular samples in torsion, round membranes designed to hidrolipoclasia, thin cut plates, flat samples with holes and round solid samples with an annular undercut with different radius cuts. The impact of volume stress state, calculated by the method of mathematical simulation of each type samples loading processes, on maximum deformation is discussed.
Izvestiya MGTU MAMI. 2015;9(2-4):44-50
44-50
Modeling of response of combustion chamber of high-altitude engine to abnormal power impacts during ground firing tests
Abstract
This article proposes a calculation-experimental method of determining the RMS of voltage levels in a sub-camera area of 14D23 high-rise four-chamber engine in terms of ground-based firing tests under the action of abnormal pulsation effects (side forces).
Izvestiya MGTU MAMI. 2015;9(2-4):51-58
51-58
The current state of computational analysis methods of strength and reliability of vehicles wheels
Abstract
The review of modern approaches to the analysis of stress-strain state of motor vehicles wheels was made. It is shown that calculations of fatigue strength and resistance to impact are based on calculation of stress-strain state of wheel after bench loading using finite element method.
Izvestiya MGTU MAMI. 2015;9(2-4):59-67
59-67
Theory of the gradual accumulation of fatigue damage in metals under proportional cyclic loading
Abstract
The paper provides system of hypotheses about the development of defects in metals at micro, meso and macro levels (such as fragile micro- and macro-cracks) under arbitrary proportional (simple) cyclic loading. The system is formulated on the basis of extensive experimental and theoretical material about fatigue failure of metals and metal alloys. For uniaxial loading the symmetrical correlations of phenomenological model of brittle fatigue loading of metals are written. The correlations cover the entire process step by step with the release of a typical state - the type of defect.
Izvestiya MGTU MAMI. 2015;9(2-4):68-75
68-75
Creep and long-term strength of rods under stretching and bending in aggressive environment
Abstract
The article describes the features of high-temperature deformation of the rods in aggressive environment. In the first section it is considered the related problem of the long-term strength of a stretched rod in aggressive environment. Unlike the known solutions, it is taken into account the interdependence of the environment concentration level in the material of the rod and the value of accumulated damage. Obtained are the values of the time before failure of the rod with different formulations of the problem. In the second section it is investigated creep of the rod in pure bending under these conditions, taking into account different rod-resistance to tension and compression. The solutions of problems at steady creep of the rod, with additional accounting of accumulated damage of the material and influence of aggressive environment.
Izvestiya MGTU MAMI. 2015;9(2-4):76-84
76-84
The concept of averaging of stresses in the problems of the two-parameter fracture mechanics
Abstract
The article illustrates the application of the Neuber-Novozhilov concept for averaging of stress to before tip of a crack/cutout in solving of contemporary problems of two-parameter fracture mechanics, aimed at creation of models and criteria of body limit state and search of a crack path. As a parameters of tightness strain in the vicinity of the crack tip are used nonsingular components of T-stresses of the stress field.
Izvestiya MGTU MAMI. 2015;9(2-4):85-90
85-90
Representation of symmetric second-rank III tensor in the space of resultant eigenvectors
Abstract
The article examines the possibility of representation of a symmetric second rank III tensor in the three-dimensional vector space of resultant eigenvectors. It has been shown that the vector space of resultant eigenvalues consists of six independent segments. Vector symmetric tensor may be represented in any of the segments independently. The authors introduce a local vector basis for each of the sectors. It is shown that the previously proposed by A.A. Ilyushin and K.F. Chernykh vector basis of the stress tensor are the second and third segments of the vector space of principal stresses.
Izvestiya MGTU MAMI. 2015;9(2-4):91-94
91-94
Elements of thermomechanics of plasticity under complex loading
Abstract
The problem of the theory of elastic-plastic process is the establishment of criteria for loading and unloading. In this paper, the equations of the process describe the transition from Euclidean metric, normal for the source deviatoric space, to internal metrics, definitely related to the processes of deformations and loadings. This transition allows without additional assumptions to introduce so-called structural parameters characterizing the irreversible behavior of the material and to build a thermomechanics variant, providing a wide range of opportunities to determine all thermodynamic parameters of the model and formulation of the thermodynamic inequalities.
Izvestiya MGTU MAMI. 2015;9(2-4):95-101
95-101
Method and some results of application of the gas-dynamic surface modification technology for machine parts to increase their lifetime
Abstract
The paper presents the mechanism of formation of the structure and properties of coatings based on copper, aluminum, nickel, zinc, inflicted by gas dynamic spraying. Presented are the results of adhesion, cohesion, resistance to corrosion, as well as the study of the coefficient of friction coatings. Showed are the examples of using of the method for restoring of worn surfaces of machine parts and for corrosion protection engineering products.
Izvestiya MGTU MAMI. 2015;9(2-4):102-108
102-108
Stability of elastoplastic thin-walled structures in implementation of complex processes of combined deformation
Abstract
In this article the problem of bifurcation of the thin-walled circular cylindrical shell under compound deformation in the moment of loss of stability is being considered. Undercritical loading is compound. It is full failed by means of axial compressing force and torque moment in the deviatoric plane A.A. Ilyushin. The condition of the incompressibility of material and the condition of the uniformity of the stressed state in the shell till the moment of loss of stability are used. The problem is solved in geometrically linear setting.
Izvestiya MGTU MAMI. 2015;9(2-4):109-114
109-114
Features of formation of the structure of turbine blade casted with given crystallographic orientation
Abstract
The paper discusses the features of formation of structure of single-crystal turbine blades casted with predetermined crystallographic orientation, allowing to obtain higher performance properties compared to conventional equiaxed structure.
Izvestiya MGTU MAMI. 2015;9(2-4):115-122
115-122
Rayleigh-Taylor instability in the high-speed collision of metal plates
Abstract
On the basis of numerical simulation the authors investigate dynamic processes occurring in the high-speed impact of the two metal plates. The calculations showed the presence of the Rayleigh-Taylor instability, growing on the boundary of metal impact. The article presents the comparative characteristic of the metal deformation processes in plane and spatial cases, calculations with different equations of state.
Izvestiya MGTU MAMI. 2015;9(2-4):123-129
123-129
VIII shkola-seminar «Sovremennye problemy nelineynoy mekhaniki»
Izvestiya MGTU MAMI. 2015;9(2-4):130-132
130-132