Stress-strain state in “coating–substrate” system after coating stability loss induced by impact of thermal stresses

2016 ◽  
Author(s):  
P. A. Lyukshin ◽  
S. A. Bochkareva ◽  
N. Yu. Grishaeva ◽  
B. A. Lyukshin ◽  
N. Yu. Matolygina ◽  
...  
Keyword(s):  
Strain State ◽  
Thermal Stresses ◽  
Stability Loss ◽  
Stress Strain ◽  
Stress Strain State ◽  
Coating Stability

NUMERICAL INVESTIGATION OF THERMOMECHANICAL PROCESSES UNDER SHORT-PULSED LASER IRRADIATION OF A HALF-SPACE

2021 ◽  
Vol 6 ◽  
pp. 55-65
Author(s):  
Kamila Storchak ◽  
◽  
Nina Yakovenko ◽  
Olga Polonevych ◽  
Irina Sribna ◽  
...  
Keyword(s):  
Residual Stress ◽  
Laser Irradiation ◽  
Half Space ◽  
Strain State ◽  
Thermal Stresses ◽  
Equations Of Motion ◽  
Thermomechanical Loading ◽  
Stress Strain ◽  
Stress Strain State ◽  
Residual Strains

The laser irradiation of metallic surfaces by intense heat sources is used for the generation of short probing pulses, which propagate into thin specimens and enable one to estimate their structure and mechanical properties within the framework of the classical acoustic approach. High thermal stresses and residual strains occur during the short-term irradiation of the surface of a construction by an energy source of high density. In the present work, we solve the axially symmetric problem of a half-space under thermomechanical loading. We take into account the influence of volume and inelastic characteristics of separate phases on the residual stress-strain state of the half-space. The statement of the problem includes: Cauchy relations, equations of motion, heat conduction equation, initial conditions, thermal and mechanical boundary conditions. The thermomechanical behavior of an isotropic material is described by the Bodner-Partom unified model of flow. The problem is solved with using the finite element technique. The numerical realization of our problem is performed with the help of step-by-step time integration. The equations of motion are integrated by the Newmark method. The residual stress-strain state is described using the method of numerical solution of the axisymmetric dynamic problem for a half-space under thermomechanical loading and the flow model. We established that microstructural transformations, which are taken into account due to the thermophase volume strain and dependence of inelastic characteristics of the material on the phase composition, significantly reduce residual inelastic strain and promote the appearance of compressive stresses. The three-zone region of residual stresses field formation is obtained.

scholarly journals Evaluation of stress-strain state of gas pipeline section with local stability loss

2015 ◽  
Vol 2015 (2) ◽  
pp. 40-47 ◽  
Author(s):  
A.A. Rybakov ◽  
◽  
E.F. Garf ◽  
A.V. Yakimkin ◽  
I.V. Lokhman ◽  
...  
Keyword(s):  
Local Stability ◽  
Strain State ◽  
Stability Loss ◽  
Gas Pipeline ◽  
Stress Strain ◽  
Pipeline Section ◽  
Stress Strain State

scholarly journals Determining thermal stresses in asphalt concrete by the method of computer simulation

2021 ◽  
pp. 105-111
Author(s):  
Volodymyr Maliar
Keyword(s):  
Finite Element Analysis ◽  
Computer Simulation ◽  
Finite Element ◽  
Asphalt Concrete ◽  
Strain State ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Stress Strain ◽  
Element Analysis ◽  
Stress Strain State

The main destructions of asphalt concrete pavement are rut, transverse cracking, fatigue failures, peeling, etc. When the pavement cools, lowtemperature damages can occur for various reasons. The sources of damages that cause such failures are not well studied, so this problem is relevant. Goal. The aim of this work was to determine the stress-strain state inside the volume of asphalt con-crete during cooling on the basis of a two composite three-dimensional model using the method of computer simulation in response to the changing structured bitumen properties. Methodology. The method of finite element analysis of the stress-strain state of the composite material was used. The material is represented by a three-dimensional (3D) model pro-posed by prof. B.S. Radovsky. Results. The finite element analysis method was used to calculate the average thermal stresses in asphalt concrete during cooling in accordance with increase of viscosity of bitumen section, which is located in asphalt concrete in a structured state. This consideration is realized on the basis of changes in a number of bitumen properties in the contact zone, in particular, the changes in the glass transition temperature. It is shown that the thermal stresses that occur during cooling by limiting the movement of asphalt concrete in the construction reach the strength values at negative temperatures, which can be used to estimate the temperature of crack formation in asphalt concrete under the condi-tion of its action in pavement (Tcr). The values of these stresses depend on the cooling rate, the bitumen content, its viscosity and structure. Originality. For the first time, it was found numerically that in the sample of asphalt concrete, which is free from restriction of movements, there are internal thermal stresses during cooling due to the difference of bitumen thermal expansion coefficients and stone materials. These stresses are up to 87 percent of the average thermal stresses that occur in the compressed sample. Practical value. The possibility of rapid estimation of thermal stresses with the possibility of predicting low-temperature cracks in asphalt concrete is shown.

Simulation of the stress-strain state and stability loss of a thermal barrier coating under thermal shock

2012 ◽  
Vol 15 (1-2) ◽  
pp. 104-111 ◽  
Author(s):  
Pepter A. Lyukshin ◽  
B. A. Lyukshin ◽  
N. Yu. Matolygina ◽  
S. V. Panin
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Strain State ◽  
Stability Loss ◽  
Thermal Barrier ◽  
Stress Strain ◽  
Stress Strain State ◽  
Barrier Coating

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

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