Prediction of contact-fatigue damage to rails using computational-experimental methods

2020 ◽  
Vol 86 (4) ◽  
pp. 46-55
Author(s):  
N. A. Makhutov ◽  
V. S. Kossov ◽  
E. S. Oganyan ◽  
G. M. Volokhov ◽  
M. N. Ovechnikov ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Software Package ◽  
Strain State ◽  
Contact Fatigue ◽  
Cumulative Distribution ◽  
Stress Strain ◽  
Stress Strain State ◽  
Contact Fatigue Life ◽  
The Impact

Analysis of the operational data related to rails failure showed that contact-fatigue defects consistently hold a prominent place. The goal of the study is to show the possibilities of using modern numerical methods in calculation assessment of the service life of rails before the onset of contact fatigue crack formation on a running surface depending on the values of axial load. To calculate a stress-strain state in the area of contact interaction between the wheel and rail a detailed finite-element model implemented in the MSC. Marc software package is used. The analysis revealed complex multiaxial and non-proportional nature of the stress-strain state. The Brown – Miller multiaxial fatigue model implemented in the MSC. Fatigue software package was taken to determine accumulation of the contact fatigue damages on a rail running surface. The model is based on the assumption that maximum fatigue damages in the metal occur in the area with the maximum shear stress. The impact of normal stresses in this area is also taken into account. The results of a comparative computational analysis of the rail life time confirm that the service life decreases with increasing axial loads, all other conditions being the same. With a share of 20% of freight trains with axle loads of 25 tonf in a daily pattern one should expect a decrease in the contact fatigue life of rails by 3 – 4 %. It is possible to improve the method for prediction of the contact fatigue life of rails in terms of experimental definition of the fatigue and strength characteristics of the rail steel depending on the degree of hardening of the running surface, their probabilistic properties and the use of a cumulative distribution of vertical forces taking into account the structure of the freight traffic passing through the section.

scholarly journals Influence of the axial loads of rolling stock on the contact-fatigue life of rails

2018 ◽  
Vol 77 (3) ◽  
pp. 149-156 ◽  
Author(s):  
V. S. Kossov ◽  
G. M. Volokhov ◽  
O. G. Krasnov ◽  
M. N. Ovechnikov ◽  
A. L. Protopopov ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Contact Fatigue ◽  
Calculated Data ◽  
Operating Conditions ◽  
Rolling Stock ◽  
Axial Loads ◽  
Rolling Surface ◽  
Contact Fatigue Life ◽  
The Impact

Analysis of operational data for defective and highly defective rails showed that up to 25 % is the contact-fatigue defects. In connection with the development of heavy haul traffic on the Russian railways, it is relevant to determine the influence of cars with increased axial loads of 25 and 27 tf on the contact fatigue life of rails. The solution of this problem is set forth in this article. The Brown-Miller model of multi-axial fatigue was used in the calculation. This model is integrated into the Fatigue software system, which is tied to the Marc calculation system through Pat-ran. Since under operating conditions the wheel moves (rolls) along the rail on meandering trajectory, in computer modeling weight coefficients were taken into account that characterize the percentage of wheels in the cross-sectional areas of the rail. Calculations of contact fatigue life took into account the variability of vertical loads from the impact on the track of trains formed from innovative open cars with axial loads of 23.5, 25 and 27 tf under operating conditions, loaded with real loading blocks. According to the analysis of calculated data with an increase in axial loads from 23.5 to 25 tf, it is necessary to expect a decrease in the service life of rails in contact fatigue resistance by 19 %, with a further increase in axle loads of up to 27 tf per 32 %. Considering that the share of freight cars with axial loads of 25 tf does not exceed 15...20 %, then on the routes of its use the service life of rails should be expected to decrease by 3...4 %. The method proposed by the authors for predicting the contact fatigue life of rails with increasing axial loads is advisable to improve in part of the experimental determination of the fatigue and strength characteristics of rail steel from the degree of hardening of the rolling surface, its probabilistic properties and the use of the integral distribution law for vertical forces, taking into account the structure of the freight traffic passing through the section. The work was carried out according to the RFBR project 17-20 01088.

scholarly journals Determination of stress-strain state of the wooden church log walls with software package

2016 ◽  
Vol 86 ◽  
pp. 02019 ◽  
Author(s):  
Anastasia Chulkova ◽  
Sergey Lukichev ◽  
Marina Romanovich
Keyword(s):  
Software Package ◽  
Strain State ◽  
Stress Strain ◽  
Stress Strain State

Simulating the stress–strain state of a thin plate after a thermal shock

2021 ◽  
Author(s):  
A. V. Sedelnikov ◽  
S. V. Glushkov ◽  
V. V. Serdakova ◽  
M. A. Evtushenko ◽  
E. S. Khnyryova
Keyword(s):  
Temperature Field ◽  
Thermal Shock ◽  
Thin Plate ◽  
Strain State ◽  
Stress Strain ◽  
Homogeneous Plate ◽  
Stress Strain State ◽  
The Impact ◽  
Elastic Elements

The paper is devoted to simulating the impact of a thermal shock on a thin homogeneous plate in the ANSYS package. The assessment of the stress–strain state is carried out and the dynamics of changes in the temperature field of the plate is determined. The obtained results were compared with the data of other authors and can be used when taking into account the thermal shock of large elastic elements of spacecraft.

scholarly journals On extending the life of nuclear reactors

2021 ◽  
Vol 2131 (2) ◽  
pp. 022030
Author(s):  
A V Kramskoi ◽  
Y G Lyudmirsky ◽  
M E Zhidkov ◽  
M I Kramskaia
Keyword(s):  
Service Life ◽  
Base Metal ◽  
Strain State ◽  
Mutual Influence ◽  
Nuclear Reactors ◽  
Test Procedure ◽  
Reactor Vessel ◽  
Stress Strain ◽  
Stress Strain State ◽  
Additional Service

Abstract To extend the service life of nuclear reactors, witness samples from the shells of the core of the reactor vessel are placed in their core. According to the requirements in force in the industry, the reference samples are loaded into the reactor plant unloaded up to the design stresses. This can lead to a biased assessment of the possible extension of the reactor’s life. In connection with the above, in order to assess the mutual influence of operating factors and the stress-strain state of the base metal and welded joints on embrittlement, the reference specimens must be loaded with a force that causes the maximum possible stresses in the specimens during the operation of the reactor. On the basis of domestic and international experience, a test procedure, design and loading scheme for compact witness samples are proposed for modeling and assessing the mutual influence of operating factors and stress-strain state on the object under study (VVER power reactor vessel). For VVER RPVs, the duration of the additional service life should be confirmed by the justification that by the end of the additional service life, the fracture toughness values of the base metal and metal of the welded seams located in the irradiation zone will allow without destruction to withstand all operational and emergency loads, as well as loads at hydraulic tests.

scholarly journals APPLICATION OF COMPUTER SIMULATION IN THE EVALUATION OF THE STRESS-STRAIN STATE OF LOAD-BEARING STRUCTURES OF BUILDINGS MASONRY

2017 ◽  
Vol 13 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Anatoliy I. Bedov ◽  
Azat I. Gabitov ◽  
Azat A. Gallyamov ◽  
Aleksandr S. Salov
Keyword(s):  
Software Package ◽  
Comparative Evaluation ◽  
Strain State ◽  
Work Load ◽  
Masonry Structures ◽  
Stress Strain ◽  
Stress Strain State ◽  
Republic Of Bashkortostan ◽  
The Republic ◽  
Manual Calculation

The results of studies on the analysis of the stress-strain state of the structures of bearing walls of high-hollow pottery. The way of modeling masonry finite element method. The experimental study of masonry structures produced in the Republic of Bashkortostan high-hollow pottery, set the nature of their work load, the mechanism of destruction. The results of the comparative evaluation of the calculations in the software package and the traditional “manual” calculation.

scholarly journals Influence of the sequence of erection of build-ings on the formation of the stress-strain state of the system «base-foundation-overhead structures»

2020 ◽  
pp. 32-44
Author(s):  
Liudmyla Skochko ◽  
Artem Shabaltun
Keyword(s):  
Strain State ◽  
Design Parameters ◽  
Soil Base ◽  
Stress Strain ◽  
High Rise ◽  
Stress Strain State ◽  
Subsequent Section ◽  
The Impact ◽  
Ground Structures ◽  
Formulation Of Problems

The influence of the order of construction of houses on the formation of the stress-strain state of the system "foundation-foundation-above-ground structures" is investigated For this purpose, several options for setting tasks for the phased construction of multi-section building sections are considered. With this in mind, it should be noted that the construction of each subsequent section has an impact on the built entirely or partially adjacent section. That is why this effect should be investigated to predict how serious this impact may be, and to draw appropriate constructive decisions. Thus, the main objectives of the study are: Creation of SEM without taking into account the stages of construction of the house; Calculation of a house with a phased loading of 5 floors. Taking into account changes in the order of construction of sections; Formation of SEM taking into account the sequence of erection of sections without including the sequence of erection of floors within the boundaries of the current section; Research of the impact of the calculation of sections of a multi-section building without and taking into account the summary of subsequent sections. The research of the impact of the sequence of construction and installation of the object will allow us to assess the stress-strain scheme at all stages of construction, so changes in the behavior of the scheme will be recorded at all stages of construction specified by the designers. To do this, the change in the stress-strain state (VAT) of the system "foundation - foundations - above-ground structures" must be modeled with different options for stages of construction, taking into account the real parameters of the soil base and so on. The interaction of piles in different zones of sections, the work of grids in the foundations of high-rise buildings are considered. The research was carried out with the help of numerical modeling of the system "foundation - foundations - aboveground constructions". The redistribution of forces in the piles depending on the formulation of problems on the stages of construction of sections and design parameters (location of piles in characteristic zones, the influence of the stiffness of the aboveground part on the redistribution of forces). Characteristic zones in the foundation are distinguished: they are central, lateral, angular and especially at the joints of adjacent sections. The redistribution of efforts between piles and a grid is revealed.  

scholarly journals Laws of gas draining in the massif disturbed by mining operations

2019 ◽  
Vol 109 ◽  
pp. 00047
Author(s):  
Serhii Kurnosov ◽  
Volodymyr Zerkal
Keyword(s):  
Strain State ◽  
Abutment Pressure ◽  
Gas Permeability ◽  
Experimental Studies ◽  
Rock Massif ◽  
Gas Release ◽  
Mining Operations ◽  
Stress Strain ◽  
Stress Strain State ◽  
The Impact

A method for calculating gas permeability of the rock massif depending on its stress-strain state is presented. By using methods of the mine experimental studies, influence of mining operations in the adjacent long walls on intensity of gas release from the previously worked-out long-pillar was determined, as well as impact of the massif stress-strain state on efficiency of the drainage boreholes. Formulas were obtained for calculating coefficients of the impact of zones with static and dynamic abutment pressure on intensity of gas draining in the previously worked-out long-pillar.

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